Medical imaging of the gastrointestinal (GI) tract is crucial for the diagnosis of GI diseases. Historically, barium techniques have been the only available method. Although many diagnoses have been made on the basis of these exams, the diagnostic performance of these exams for certain abnormalities has been disappointing.
6 Liver QUESTIONS Match each labeled structure (A to L) with the corresponding anatomic description (1 to 12) The image on the left labeled with structures A to F shows the liver above the horizontal plane of the right and left portal veins The image on the right labeled with structures G to L shows the liver below this plane Each option may be used only once What is the most likely cause of the liver abnormality in this patient with cardiac disease? A Radiation therapy B Total parenteral nutrition C Hepatorenal syndrome D Iodine deposition For patients in questions to 7, select the most likely diagnosis (A to F) for the hepatic masses Each option may be used once, more than once, or not at all A Cavernous hemangioma B Hepatocellular adenoma C Focal nodular hyperplasia D Hepatocellular carcinoma E Cholangiocarcinoma F Abscess A 63-year-old woman with right upper quadrant pain and a liver finding noted on ultrasound Images are from an MRI using conventional extracellular gadolinium contrast FS T2W, arterial phase T1W+gad, and delayed phase T1W+gad A 47-year-old woman with cirrhosis secondary to hepatitis C Images from an MRI performed with conventional extracellular gadolinium contrast are shown Top row: T2W and FS T1W Bottom row: Arterial and delayed phase FS T1W+gad A 46-year-old woman with painless jaundice Images from an MRI performed with conventional extracellular gadolinium contrast are shown Top row: T2W and FS T1W Bottom row: Arterial and delayed phase FS T1W+gad A 21-year-old woman found to have a liver lesion on ultrasound Images from an MRI using hepatobiliary gadolinium contrast agent gadoxetate disodium (Eovist—Bayer HealthCare) are shown T2W, arterial phase FS T1W+hepatobiliary gad, and 20-minute FS T1W+hepatobiliary gad A 51-year-old man with hepatitis B and cirrhosis Images from an MRI performed with hepatobiliary contrast agent are shown FS T2W, arterial phase FS T1W+hepatobiliary gad, and a 20-minute FS T1W+hepatobiliary gad Which of the following would be considered an ancillary feature favoring hepatocellular carcinoma rather than a major feature according to the Liver Imaging Reporting and Data System (LI-RADS)? A Washout appearance B Capsule appearance C Arterial enhancement D Hepatobiliary phase hypointensity Images from a CT on a 55-year-old man with hepatitis C and cirrhosis are shown Arterial phase images are shown on the left, and delayed images are shown on the right Which LI-RADS category best fits the findings? A LR-2 probably benign B LR-3 intermediate probability for hepatocellular carcinoma C LR-4 probably hepatocellular carcinoma D LR-5 definitely hepatocellular carcinoma 10a A 24-year-old man with no history of liver disease presents with epigastric pain and vomiting A transverse image from an abdominal ultrasound is shown What is the most likely diagnosis? A B C D Hemangioma Hepatocellular carcinoma Angiomyolipoma Metastasis 10b What finding is indicated by the arrow on this sagittal ultrasound image from the same patient? A B C D Lung nodule Mirror artifact Peritoneal nodule Twinkle artifact 11 A 22-year-old patient presents with abdominal pain A venous phase CT and hepatic venogram are shown Which of the following is the most common known etiology of this disease process? A Thrombophilia B Viral hepatitis C Alcohol abuse D Congenital defect For the patients in questions 12 to 15, select the most likely diagnosis (A to F) Each option may be used once or not at all A Von Meyenburg complex B Pyogenic abscess C Biliary cystadenoma/cystadenocarcinoma D Peritoneal carcinomatosis E Polycystic liver disease in autosomal-dominant polycystic kidney disease F Subcapsular hematoma 12 A 26-year-old woman with abdominal pain, nausea, and vomiting 13 A woman with chronic renal failure, fatigue, and decreasing hematocrit FS T2W, T1W MRI, and venous phase CT 14 A 63-year-old man with pancreatic cancer status post common bile duct stent placement complains of worsening pain 15 A 75-year-old man with multiple liver lesions noted on ultrasound 16 What is the dominant cirrhotic feature on the FS T1W MR image shown? A B C D Right posterior hepatic notch sign Macronodularity Caudate lobe hypertrophy Expanded gallbladder fossa sign 17 Regarding contrast agent selection for liver MRI, which of the following indications has the best consensus for the use of a hepatobiliary contrast agent such as gadoxetate disodium (Eovist—Bayer HealthCare) over a conventional extracellular contrast agent? A Assessing for residual or recurrent hepatocellular carcinoma after transarterial chemoembolization B Differentiating between focal nodular hyperplasia and hepatocellular adenoma C Confirming a hemangioma D Screening for hepatocellular carcinoma in a patient with hemochromatosis 18 A 54-year-old man undergoes MR imaging for evaluation of a liver mass Among the choices listed, which is the most likely diagnosis? Venous phase FS T1W+gad and T2W MRI A B C D Metastasis Hemangioma Simple cyst Focal nodular hyperplasia 19a A 35-year-old man with end-stage renal disease underwent an abdominal ultrasound as part of preoperative evaluation for renal transplant An MRI was performed to further evaluate an abnormal liver The cause of the disease process revealed on these T1W GRE in-phase and out-of-phase images is most likely: A B C D Viral hepatitis Blood transfusions Alcohol consumption Hereditary depositional disease 19b Which of the following parameters would be the most effective for reducing T2* effect and susceptibility artifact? A Gradient-echo sequence and shorter TE B Gradient-echo sequence and longer TE C Fast spin-echo sequence and shorter TE D Fast spin-echo sequence and longer TE 20a A 46-year-old woman with breast ductal carcinoma in situ (DCIS) was found to have a liver lesion on breast MRI Dedicated liver MRI was performed with a conventional extracellular contrast agent for further evaluation What is the most likely diagnosis? Top row: FS T2W and FS T1W Bottom row: Arterial and delayed phase FS T1W+gad A B C D Hemangioma Metastatic breast cancer Abscess Hepatocellular carcinoma 20b This is the arterial phase postcontrast T1W image from the previous case What finding is indicated by the arrows? A B C D Poor fat saturation Focal fatty sparing Transient hepatic intensity difference (THID) Hemorrhage 21 A 77-year-old man with chronic hepatitis B undergoes a screening MRI using conventional extracellular contrast agent What is the most likely diagnosis? Top row: In-phase and out-of-phase T1W Bottom row: Arterial and delayed phase FS T1W+gad A B C D Hepatocellular carcinoma Hepatocellular adenoma Angiomyolipoma Nodular steatosis 22a A 19-year-old man was injured in a motor vehicle collision Which statement is TRUE regarding the management of the liver findings on CT? A B C D Partial hepatic resection is indicated for extent of laceration Angiography is indicated for embolization of a pseuodaneurysm No intervention is needed if patient is hemodynamically stable Percutaneous catheter placement is indicated for subcapsular hematoma 22b The patient was hemodynamically stable and managed conservatively Within 24 hours, the patient developed jaundice, which prompted a HIDA scan What is the diagnosis? A B C D Intrahepatic bilomas Intraperitoneal bile leak Common bile duct obstruction Gallbladder laceration 23 A 52-year-old woman undergoes a CT scan with images shown below Imaging findings are consistent with: A B C D Cholangiocarcinoma Hemangioma Lymphadenopathy Portal vein occlusion 24a A 30-year-old woman is evaluated for a liver lesion that was incidentally noted at the time of a pelvic ultrasound Which of the following statements is TRUE about the finding in the right lobe of the liver? Top row: Noncontrast and arterial phase CT Bottom row: Venous and delayed phase CT A The finding demonstrates washout appearance and is most likely a malignancy B The finding is likely a mass of hepatocellular origin C The finding is likely a transient hepatic attenuation difference (THAD) D The finding demonstrates a central scar 24b Hepatocellular adenomas in which of the following groups of patients have the highest risk of malignant transformation to hepatocellular carcinomas? A Women using oral contraceptives B Men C Patients with diabetes D Patients with steatosis in the background liver Answers: Patient 1: A Rectus sheath hematomas Patient 2: D Scar endometriosis Patient 3: B Undescended testis Patient 4: C Desmoid tumors Diagnoses to consider in patients with abdominal wall masses are listed below Differential Diagnosis of Abdominal Wall Masses Patient with a decrease in hematocrit has bilateral rectus sheath hematomas There are spindle-shaped heterogeneous masses expanding the rectus sheath bilaterally on this CT without IV contrast There is layering high density in the collection on the left representing a serum-hematocrit level, a sign that helps in the diagnosis Hematomas of the anterior abdominal wall frequently involve the rectus sheath Risk factors include trauma, surgery, anticoagulation, and coughing This 93-year-old patient was being heparinized for dialysis and coughing because of pneumonia Occasionally, active hemorrhage may be identified on a contrast-enhanced exam Patient has scar endometriosis with the classic history of cyclical abdominal wall pain associated with her menses Postcontrast axial MR image shows an infiltrative enhancing mass involving the left rectus muscle (long arrow on the following image) The sagittal image demonstrates a Caesarean section scar in the low anterior uterus (short arrow on the following image) Scar endometriosis is the result of incorporation of endometriomas into the abdominal wall at the time of gynecologic surgery, typically during Caesarean section These implants can enhance and show color Doppler vascular flow Cyclical abdominal pain does not always occur, and patients may be asymptomatic Women of childbearing age may also develop desmoid tumors in the abdominal wall with or without a history of gynecologic surgery Desmoid tumors are typically less vascular Scar endometriosis Patient has an undescended testis (cryptorchidism) Only one testis was palpable in the scrotum of this adolescent on physical exam An ovoid structure is seen in the right anterior pelvic wall (arrows on the following images), with the suggestion of a triangular epididymal head at the superior pole on the coronal view On the normal left side, the spermatic cord (short arrows on the following coronal image) is seen in the inguinal canal extending into the scrotum, but this is absent on the cryptorchid right side An undescended testis may be atrophic and not initially recognized In this case, low-dose CT was performed, but an ultrasound may identify the location of an undescended testis without radiation exposure Even if orchiopexy is performed to relocate the testis, patients with cryptorchidism continue to have increased risk of subfertility and testicular cancer, requiring continued surveillance Undescended testis Patient is a young patient with familial adenomatous polyposis (FAP) and Gardner syndrome The CT shows hypovascular soft tissue masses (arrows on the following images) in the rectus muscle and mesentery consistent with abdominal and intra-abdominal desmoid fibromatosis Gardner syndrome is associated with desmoid tumors in about 20% of patients There is a strong association with prior surgery as >80% of patients with FAP and desmoid tumor have had surgery, most commonly a total colectomy Desmoid tumors have a spectrum of appearances depending on their underlying composition Enhancement is variable, but in general, there is little to no enhancement appreciated on CT Those with a greater amount of collagen have the appearance of soft tissue, while those with greater amount of myxoid components appear more cystic These tumors are in the spectrum of “deep fibromatosis” and grouped by site of origin into intra-abdominal (including mesenteric), abdominal (wall), and extra-abdominal fibromatosis Although it is considered a benign or low-grade neoplasm that does not metastasize, desmoid fibromatosis is locally aggressive and may cause complications such as bowel obstruction and fistulas The disease is often difficult to locally control, and patients frequently recur despite resection and chemoradiotherapy Metastatic disease and lymphoma are in the differential diagnosis of abdominal and mesenteric masses but are less likely given the clinical history Desmoid tumors in patient with FAP References: Gidwaney R, Badler RL, Yam BL, et al Endometriosis of abdominal and pelvic wall scars: multimodality imaging findings, pathologic correlation, and radiologic mimics Radiographics 2012;32(7):2031– 2043 Gore RM, Ghahremani GG, Donaldson CK, et al Chapter 112: Hernias and abdominal wall pathology In: Gore RM, Levine MS (eds) Textbook of gastrointestinal radiology, 4th ed Philadelphia, PA: Elsevier/Saunders, 2015:2053–2076 Levy AD, Rimola J, Mehrotra AK, et al From the archives of the AFIP: benign fibrous tumors and tumorlike lesions of the mesentery: radiologic–pathologic correlation Radiographics 2006;26(1):245–264 10 Answer D.This is a ring artifact indicating a miscalibrated or defective detector element It is corrected by recalibration or replacement of the detector The multiple concentric rings are prominent in this case, but if the artifact is more subtle, one of the rings more centrally may be mistaken for a mass The other answer choices not produce concentric ring artifacts Beam hardening causes central low-density areas (cupping) or streaking X-ray tube arcing can occur with contamination by gas or impurities in the tube or the oil surrounding the tube resulting in intermittent loss of x-ray output This may manifest as increased noise and lines across the image In another form of x-ray tube malfunction that requires tube replacement, the ball bearings that spin the anode are failing, producing a humming noise and vibration that cause lines across the image as shown on the following image Artifact from failing x-ray tube, accompanied by humming noise and vibration Slip ring artifacts may appear as lines across the images as well The slip ring allows the gantry to rotate smoothly and rapidly The slip ring also facilitates transmission of power and data signals Slip ring artifacts are produced when there is loss of normal contact between the slip ring and the various stationary CT components This results in lines of incomplete data across the image References: Barrett JF, Keat N Artifacts in CT: recognition and avoidance Radiographics 2004;24(6):1679–1691 Boas FE, Fleischmann D CT artifacts: causes and reduction techniques Imaging Med 2012:4(2):229–240 11 Answer A.Multiple mechanisms account for metal artifacts, such as beam hardening, scatter, photon starvation, edge gradient effects, and narrow window of the CT scale With beam hardening, the lower-energy photons are absorbed more rapidly so that the resulting data not reflect true tissue density, and bands or streaks are seen Photon starvation occurs because not enough photons are reaching the detectors, resulting in data noise Some techniques are listed below that may reduce the conspicuity of metal artifacts Techniques for Reducing Metal Artifacts on CT References: Barrett JF, Keat N Artifacts in CT: recognition and avoidance Radiographics 2004;24(6):1679– 1691 Boas FE, Fleischmann D CT artifacts: causes and reduction techniques Imaging Med 2012:4(2):229–240 Lee MJ, Kim S, Lee SA, et al Overcoming artifacts from metallic orthopedic implants at high-field-strength MR imaging and multi-detector CT Radiographics 2007;27(3):791–803 12 Answer A.Chemical shift artifacts type I and II are seen where fat and water protons meet inside the body The dark line seen on the left-sided margin of both kidneys is a type I chemical shift artifact, a phenomenon seen in the frequency-encoding but not phase-encoding direction The frequency-encoding direction in abdominal imaging is usually assigned to the transverse dimension (so that phase encoding can be assigned to the shorter anteroposterior dimension and decrease scan time); therefore, this artifact is usually seen in the transverse dimension The corresponding bright line at the opposite (right-sided) margin of both kidneys is less conspicuous because of the brightness of the perirenal fat Whether the black and white lines are seen on the left or right side depends on whether the frequency-encoding gradient is increasing or decreasing from left to right Type I chemical shift artifact is due to spatial misregistration Spatial localization in the frequency direction is inferred by the frequency of precession of the proton However, protons in the water precess at a slightly different frequency than that of fat The MRI scanner misinterprets and presents this as a difference in spatial location, as depicted on the following diagram Spatial misregistration in type I chemical shift The misregistration is worse (the line is thicker) at tesla than 1.5 tesla because the difference in precession frequency between water and fat protons is larger at greater field strengths The artifact may be reduced by increasing the receiver bandwidth or using a fat suppression technique Swapping the phase and frequency directions may move the artifact to a different location if it is problematic Type II chemical shift involves out-of-phase protons within the same pixel Shimming improves magnetic field homogeneity, which does not improve type I chemical shift artifact References: Huang SY, Seethamraju RT, Patel P, et al Body MR imaging: artifacts, k-space, and solutions Radiographics 2015;35(5):1439–1460 Morelli JN, Runge VM, Ai F, et al An image-based approach to understanding the physics of MR artifacts Radiographics 2011;31(3):849–866 13 Answer B.This axial image from a liver MRI exam demonstrates repetitive shading and ghosting matching the contour of the anterior and posterior abdominal walls, caused by patient respiratory motion Patient motion, which may be voluntary or involuntary, can cause ghosting, blurring, signal loss, and misregistration Motion artifacts are most prominent in the phase-encoding direction, which is typically anteroposterior in abdominal imaging Techniques to reduce motion artifacts are listed in the table below Among the other answer choices, pulsatile flow artifact can cause repetitive ghosting at regular intervals, but it does not involve the entire abdominal wall Large patient body habitus places parts of the patient in the periphery of the magnetic field, where the image is prone to susceptibility and other effects related to field inhomogeneity Patient body habitus may also contribute to dielectric artifacts A radiofrequency (RF) spike or interference results in a herringbone or zipper artifact with one or more lines across the image Techniques to Reduce Motion Artifacts References: Huang SY, Seethamraju RT, Patel P, et al Body MR imaging: artifacts, k-space, and solutions Radiographics 2015;35(5):1439–1460 Morelli JN, Runge VM, Ai F, et al An image-based approach to understanding the physics of MR artifacts Radiographics 2011;31(3):849–866 14 Answer D.Slice oversampling will decrease this 3D wraparound (aliasing) artifact On these 3D volumetric GRE images, the bowel and lumbar spinal structures from the patient’s lower abdomen are superimposed on the heart and lungs in the patient’s lower chest This occurs at the slices at the most superior and inferior aspect of the imaging volume This is analogous to the phenomenon seen on 2D images in the phase-encoding direction when using small fields of view, for example, on the following axial image of the spine (arrows) shown below Slice oversampling (obtaining more slices in the z-axis above and below the volume of interest) can reduce 3D wraparound artifact 2D wraparound artifact In a 3D sequence, frequency encoding is performed on one axis and phase encoding on the other two axes (including the slice selection axis in the zdirection) Aliasing can occur along the z-axis if the slab excitation includes anatomy in the z-axis outside what is encoded The signal is not sampled with enough phase-encoding steps to correctly localize the data, and the MRI system erroneously maps these signals to the opposite end of the axis Ways to decrease this artifact are listed in the following table Regarding the other answer choices, frequency oversampling would correct aliasing in the frequency-encoding direction, which is not the direction of wraparound in this case Aliasing in the frequency-encoding direction is essentially no longer encountered in clinical practice, as modern MRI systems automatically correct this by automatic frequency oversampling, which is performed without a time penalty The artifact shown in this case is unrelated to motion, so neither respiratory nor cardiac gating (other incorrect answer choices) would reduce this artifact Techniques to Decrease Wraparound Artifact References: Huang SY, Seethamraju RT, Patel P, et al Body MR imaging: artifacts, k-space, and solutions Radiographics 2015;35(5):1439–1460 Morelli JN, Runge VM, Ai F, et al An image-based approach to understanding the physics of MR artifacts Radiographics 2011;31(3):849–866 15 Answer C.The curvilinear bands at the outer edges of the field on this balanced steady-state free precession (SSFP) gradient echo sequence are called moiré fringes This is a type of banding artifact that is particularly apparent on balanced SSFP sequences Balanced SSFP is a fast-acquisition gradient echo sequence with a high signal to noise ratio It has a prominent role in abdominal imaging where high contrast between fluid and surrounding tissue is necessary, such as for MR cholangiopancreatography and MR enterography This sequence is particularly sensitive to inhomogeneities in the magnetic field The inhomogeneities disrupt the rephasing that needs to occur repeatedly to produce a coherent vector at the end of every TR interval The results of these phase errors are curvilinear bands of signal loss that are worse where there is field inhomogeneity, such as the periphery of the field of view and interfaces with gas-containing organs such as lungs and bowel The effect is similar to looking through two superimposed window screens Ways to reduce the moiré fringes include: Using FOV smaller than the field and ensuring anatomy of interest is centered in the MRI system Scanning at 1.5 tesla rather than tesla Using shorter TR Shimming to improve field homogeneity This effect is considered separate from T2* susceptibility artifact Wraparound, or aliasing, of anatomy usually occurs in the phase direction and is due to small field of view and undersampling Herringbone artifact (also known as corduroy, or spike artifact) is one appearance of radiofrequency (RF) interference (A zipper artifact is another appearance of RF interference.) In the herringbone artifact, multiple parallel lines are seen as demonstrated on the following cervical spine MR image It occurs when there is a corruption during the filling of K-space, most commonly from a transient electromagnetic spike This spike may occur from intrusion of signals occurring outside or inside the system, and troubleshooting of the system is required if the artifact is persistent Herringbone artifact from RF interference References: Huang SY, Seethamraju RT, Patel P, et al Body MR imaging: artifacts, k-space, and solutions Radiographics 2015;35(5):1439–1460 Morelli JN, Runge VM, Ai F, et al An image-based approach to understanding the physics of MR artifacts Radiographics 2011;31(3):849–866 16 Answer B.The MR images demonstrate the navigator pulse technique being applied with the purpose of decreasing respiratory motion artifact Respiratory motion may dramatically compromise image quality in abdominal imaging Multiple techniques have been developed to decrease the effects of respiratory motion, including faster sequences, segmentation of the acquisitions, or a bellows device strapped to the patient’s abdomen to trigger image acquisition at end expiration The navigator technique is a form of respiratory gating that tracks respiration and times the scans to reduce respiratory motion artifact without extra equipment A continuous 90 degree navigator pulse is applied at the dome of the diaphragm (blue box on the image on the left) The resulting image on the right is known as a pencil beam The white area in the bottom half of the image is the liver and the dark area above is the lung The motion of the diaphragm is traced in real time along the x-axis The white peaks represent end expiration, the optimal time for data acquisition with the least amount of motion The software plans for the sequences placing red blocks at the white peaks The red blocks are replaced by yellow blocks during data acquisition The shape of the peak changes during acquisition because the tracking pulse is turned off to avoid cross talk This particular application of navigator technique does not affect the other three answer choices Frequencyselective fat saturation is improved by improving homogeneity of the magnetic field Spatial resolution is improved by increasing field matrix at the expense of signal to noise ratio Wraparound (aliasing) is correctable by oversampling in the phase-encoding direction(s) References: Huang SY, Seethamraju RT, Patel P, et al Body MR imaging: artifacts, k-space, and solutions Radiographics 2015;35(5):1439–1460 Morelli JN, Runge VM, Ai F, et al An image-based approach to understanding the physics of MR artifacts Radiographics 2011;31(3):849–866 17 Answer A.There is a large area of signal loss in the region of the left hepatic lobe on the axial T2W spin-echo image that is not apparent on the coronal T2W gradient-echo image This appearance is consistent with the dielectric artifact (or “standing waves”), which is a result of the interactions of the soft tissues with the electric component of an electromagnetic field An electric field always coexists with a magnetic field When the wavelength of the transmission radiofrequency (RF) pulse approaches or becomes shorter than the diameter of the patient, these interactions come into play Standing waves can develop, causing shading with areas of increased or decreased signal intensity Large volumes of intra-abdominal fluid such as ascites or amniotic fluid can also contribute to large signal voids in the central torso Dielectric artifacts are worse at tesla than 1.5 tesla, because the RF of the transmission field is at a higher frequency This shortens the wavelengths to a distance that more closely approximates the size of many adult torsos (26 cm at tesla, compared to 52 cm at 1.5 tesla) The dielectric effect may be seen on one or multiple series, depending on the field of view and other parameters affecting soft tissue interactions To reduce the dielectric artifact: Apply dielectric pads to the patient’s body to simulate body mass Use multichannel transmit arrays, which tailor the RF waveforms to compensate for the spatial variations Image at 1.5 tesla instead of tesla A metallic foreign body can cause susceptibility artifact with blooming and signal dropout, but the artifact typically worsens on a gradient-echo sequence In this case, the artifact is seen on the spin-echo sequence (image on the left) and not seen at all on the gradient-echo sequence (image on the right), eliminating the possibility of metal artifact in the patient Motion typically causes an appearance of ghosting, not a large focal area of signal dropout Flow voids of this size are not expected in the left lobe of the liver Even if there were an unusually large aneurysm or arteriovenous malformation visible on the black blood sequence spin-echo sequence, there would be a corresponding mass that would also be appreciated on the bright blood gradient-echo sequence References: Christianson KL, Hoang PB, Huang S, et al Chapter 9: Motion, pulsation, and other artifacts In: Mangrum WI, Christianson KL, Duncan SM, et al (eds) Duke review of MRI principles: case review series Philadelphia, PA: Mosby, 2012:127–151 Huang SY, Seethamraju RT, Patel P, et al Body MR imaging: artifacts, k-space, and solutions Radiographics 2015;35(5):1439–1460 18 Answer B.These are T1W gradient echo in- and out-of-phase images without IV contrast The appearance of the out-of-phase image is characterized by type II chemical shift, which manifests as the black boundary artifact (also known as the India ink or etching artifact) around structures with a fat–water interface The black boundary artifact can be identified within an organ if there is a mass that contains macroscopic fat, such as this incidental renal angiomyolipoma (AML) (arrow) The AML, which contains macroscopic fat, is bright on both of the nonfat–saturated T1 images It has a black boundary with the surrounding renal parenchyma on the out-of-phase image The following image on the right is a noncontrast fat-saturated T1W image showing that this lesion loses signal intensity, behaving as expected for macroscopic fat Renal AML with black boundary and fat saturation A clear cell renal cell carcinoma and other lesions that contain microscopic fat should demonstrate an area of signal dropout on the out-of-phase image rather than a thin peripheral boundary A renal stone of this size would be dark on all MRI sequences A renal cyst may be T1 hyperintense if it is proteinaceous or hemorrhagic, but the black boundary artifact is not associated with such cysts Incidentally, T1 hyperintense bile is noted in the patient’s gallbladder, a common finding which usually indicates concentrated bile or sludge Type II chemical shift artifact occurs in any direction with a fat–water interface, not just the frequency-encoding direction that is seen with type I chemical shift The TE is selected specifically such that the fat and water spins located in the same pixel are out of phase, at about 2.3 msec in a 1.5 tesla magnet (Timing is different in tesla magnets.) The signals cancel each other out, creating the black boundary artifact within the pixel This artifact is not seen when a TE is chosen that achieves an in-phase image (around 4.6 msec, double that of the out-of-phase image) or if fat saturation is applied References: Duncan SM, Amrhein TJ Chapter 7: Chemical shift type artifact In: Mangrum WI, Christianson KL, Duncan SM, et al (eds) Duke review of MRI principles: case review series Philadelphia, PA: Mosby, 2012:99–110 Israel GM, Hindman N, Hecht E, et al The use of opposed-phase chemical shift MRI in the diagnosis of renal angiomyolipomas AJR Am J Roentgenol 2005;184(6):1868–1872 Index A Abdominal aortic aneurysm (AAA) Abdominal compartment syndrome (ACS) Abdominal distension Abdominal hysterectomy Achalasia dysphagia epiphrenic diverticulum Acute acalculous cholecystitis (AAC) Acute appendicitis Acute cholecystitis complications of features of hepatobiliary scintigraphy for Acute colonic pseudoobstruction (ACPO) management pathophysiology Acute high-grade bile duct obstruction Acute pancreatitis (AP) Acute peripancreatic fluid collections (APFCs) Adenomatous polyposis coli (APC) Adenomyomatosis Adhesions Afferent limb normal syndrome Alcoholic liver disease Allogenic bone marrow transplantation American Association for the Surgery of Trauma (AAST) American College of Radiology (ACR) American trypanosomiasis See Chagas disease Ampullary carcinoma Amyand hernia Aneurysms Angiography with embolization superior mesenteric artery Angiomyolipomas (AMLs) Angiosarcoma Angiotensin-converting enzyme (ACE) Anisakis Annular pancreas Anterior pararenal space Anterior renal fascia Aortoenteric fistulas Apparent diffusion coefficient (ADC) Appendiceal cystadenoma Appendiceal neoplasm Appendicitis, acute Appendicoliths Arterioportal shunting Artifacts chemical shift comet tail to decrease respiratory motion artifact dielectric effect metallic foreign body mirror Moiré fringe motion, techniques patient breathing renal angiomyolipoma ring down slice oversample slip ring wraparound Ascaris A lumbricoides Ascites Aspiration Autoimmune pancreatitis (AIP) Autosomal dominant polycystic kidney disease (ADPCKD) Autosplenectomy B Barium coating Barium enema cobblestoning appearance colonic caliber Crohn disease double-contrast lead pipe appearance segmental fixed stricture Barium esophagram diabetes dysphagia esophageal carcinoma Barium pharyngoesophagram Barotrauma Barrett esophagus, prevalence of Bartonella Beckwith-Wiedemann syndrome Beger procedure Bezoar Bile ducts and gallbladder acute acalculous cholecystitis (AAC) acute cholecystitis acute high-grade bile duct obstruction adenomyomatosis ampullary carcinoma bile flow artifact bile leak (Bile leak) biliary strictures See (Biliary strictures) choledocholithiasis common hepatic duct congenital hepatic fibrosi crossing vessel indeterminate polyps inflammatory bowel disease Mirizzi syndrome papillary stenosis periportal edema pneumobilia polyps recurrent primary sclerosing cholangitis recurrent pyogenic cholangitis surgical clip vicarious excretion of contrast Bile leak Biliary cystadenocarcinoma (BCAC) Biliary cystadenoma (BCA) Biliary ductal anatomy Biliary strictures benign stricture related to prior hepatobiliary surgery Bismuth-Couinaud system Blunt trauma Brachytherapy radiation seed Breast cancer Brunner glands Budd-Chiari syndrome (BCS) C Calcification, in branching pattern Candida esophagitis Carcinoid syndrome Caroli disease Catheter-related thrombosis Cavitary mesenteric lymph node syndrome (CMLS) Cecal volvulus Celiac disease Central pancreatectomy Chagas disease Chemical shift artifacts Chilaiditi sign Cholangiocarcinoma (CCA) classification morphologic type Cholecystitis acute chronic Choledochal cysts Todani classification of Choledocholithiasis Cholelithiasis See also Gallstones Closed loop obstruction Clostridium difficile Colonic pneumatosis Colonic polyposis syndromes Colonic pseudoobstruction Colonography Colorectal cancer Colorectal lymphoma Colovesical fistula Comet tail artifact Common bile duct (CBD) Congestive heart failure Crohn colitis Crohn disease ileal strictures immunosuppressive therapy vs ulcerative colitis Cryptosporidium Cystic fibrosis (CF) Cystic pancreatic neoplasms Cytomegalovirus (CMV) D Daughter cysts Deglutition process Desmoid tumors Detector element miscalibration or defect Diaphragmatic rupture signs of traumatic Diarrhea celiac disease colonoscopy ileal carcinoid and calcified nodal metastasis infection non-Hodgkin lymphoma small bowel Distal pancreatectomy Diverticular bleeding Diverticulitis cause colovesical fistula management Duodenal diverticula Duodenal filling defect Duodenal wall thickening Dysphagia achalasia aspiration barium pharyngoesophagram Candida esophagitis eosinophilic esophagitis esophageal carcinoma gastroesophageal reflux disease leiomyomas Schatzki ring Zenker diverticulum E Echinococcal cysts Ectopic pancreatic rest Embolic disease Emphysematous cholecystitis Eosinophilic esophagitis Eosinophilic gastroenteritis Epiploic appendagitis Erythematous skin change Esophageal squamous cell cancer risk factors for development Esophageal varices Esophagus adenocarcinoma cancer, surgical resection of caustic ingestion esophageal intramural pseudodiverticulosis (EIP) esophageal leiomyomatosis free perforation of gastroesophageal reflux disease F Familial adenomatous polyposis (FAP) Fat necrosis Feline esophagus Femoral hernias Fibrolamellar hepatocellular carcinoma (FHCC) Focal nodular hyperplasia (FNH) Food impaction Foramen of Winslow Frey procedure Fundal diverticula G Gallstone ileus biliary enteric fistula bowel obstruction Gallstones See also Cholelithiasis Gangrenous cholecystitis Gas bubble motion artifact Gastric band procedure diverticulum emphysema, benign erosions mucosa outlet obstruction Gastrinoma triangle Gastroesophageal reflux disease (GERD) diagnosis dysphagia Gastrogastric fistula Gastrointestinal stromal tumor (GIST) cystic transformation malignant potential of Gaucher disease Giant cavernous hemangiomas (GCAs) Giant inflammatory sigmoid diverticulum Glucagon Gossypibomas Graft vs host disease Griffiths critical point Groove pancreatitis Gunshot wounds H Hamartoma Helicobacter pylori gastritis Hepatic artery aneurysms Hepatic infarction Hepatobiliary phase hypointensity Hepatobiliary scintigraphy Hepatobiliary surgery Hepatocellular adenomas (HCA) subtypes Hepatocellular carcinoma (HCC) Hereditary nonpolyposis colorectal cancer (Lynch syndrome) Hernia repair mesh Herpes simplex virus (HSV) Heterotopic gastric mucosa Hiatal hernia Hydatid disease I Ileocolic intussusception Immunosuppressive therapy Inflammatory bowel disease Inflammatory esophagogastric polyp Inguinal region hernias Intraductal papillary mucinous neoplasm (IPMN) Intramural pseudodiverticula Ischemic colitis K Kasabach-Merritt syndrome Killian-Jamieson diverticulum Klippel-Trenaunay syndrome L Laparotomy pad Lap-belt compression injury Large bowel obstruction (LBO) Lateral pharyngeal pouches Lateroconal fascia Leiomyomas Linitis plastica Liposarcoma Lisinopril Liver acute hepatitis angiosarcoma arterial phase arterioportal shunting biliary hamartomas blood transfusions cholangiocarcinoma conventional extracellular contrast agents diffuse hepatic hyperdensity fat saturation fibrolamellar hepatocellular carcinoma (FHCC) focal nodular hyperplasia (FNH) graft failure after transplant hemangioma hepatic artery stenosis hepatic infarction of hepatic steatosis hepatobiliary phase hypointensity hepatocellular adenoma hepatorenal syndrome injury, AAST classification of intrahepatic bilomas iodine deposition LI-RADS lobes macronodularity metastasis MRI multifocal steatosis peliosis hepatis portal vein thrombosis (PVT) pulsatile flow artifact subcapsular hematoma T2* susceptibility effects thrombophilia transient hepatic intensity difference (THID) transplant venous phase Liver Imaging Reporting and Data System (LI-RADS) Lower esophageal sphincter (LES) Lymphangiomas Lynch syndrome M Macronodularity Malignant peripheral nerve sheath tumor (MPNST) Malignant portal vein thrombus Meckel diverticulum Melena, gastrointestinal stromal tumor (GIST) Mesenteric ischemia Mesothelioma benign cystic malignant peritoneal Metal artifacts, reducing techniques for Mickey Mouse configuration Mirizzi syndrome Mirror artifact Misty mesentery Moiré fringe artifacts Motility, abnormal MR cholangiopancreatography (MRCP) MR enterography MR pelvis, with T1-weighted fat-suppressed imaging Mucinous cystic neoplasm Mucocutaneous pigmentation perioral region Mucosa-associated lymphoid tissue (MALT)–type lymphomas Multiple endocrine neoplasia type (MEN-1) N Navigator technique Neck, gunshot wounds Necrosectomy Neuroendocrine tumors (NETs) Neutropenic colitis Nodular regenerative hyperplasia (NRH) Nonsteroidal anti-inflammatory drugs (NSAIDs) O Odynophagia Ogilvie syndrome See Acute colonic pseudoobstruction (ACPO) Omental infarction Omphalomesenteric duct (OMD) Osteomas P Pancreas divisum Pancreatic duct Pancreatic ductal adenocarcinoma (PDA) Pancreatic neuroendocrine tumor Pancreatic rests Pancreatitis, acute Atlanta classification of fluid collections Balthazar CT severity index chronic with duct stone necrotizing walled-off necrosis Papillary stenosis Paraduodenal hernias (PDHs) Paragangliomas Peliosis hepatis Peripheral vascular disease Periportal edema Perirenal space Peritoneal carcinomatosis Peritoneal inclusion cyst (PIC) Peritoneum falciform ligament gastrocolic ligament hepatoduodenal ligament lesser sac ovarian carcinoma paracolic spaces Rigler sign sclerosing mesenteritis small bowel mesentery subhepatic spaces subphrenic spaces supramesocolic compartment Peutz-Jeghers syndrome Pharyngeal constrictor muscles Photon starvation Phrygian cap Phytobezoar See Bezoar Plummer-Vinson syndrome Pneumatosis Pneumobilia Pneumomediastinum Pneumoperitoneum Polycystic liver disease (PLD) Polyps gallbladder gastric hyperplastic inflammatory esophagogastric postinflammatory Polysplenia Porcelain gallbladder Portal hypertension common causes of Portal vein occlusion Portal vein thrombosis (PVT) Portal venous gas Positron emission tomography–computed tomography (PET-CT) Postcholecystectomy strictures Postcholecystectomy syndrome Posterior pararenal space Posterior renal fascia Postinflammatory polyp Posttransplant lymphoproliferative disorder (PTLD) Primary sclerosing cholangitis (PSC) Progressive systemic sclerosis Proton pump inhibitor Pseudoachalasia Pseudocirrhosis Pseudocyst derivation Pseudolipoma, IVC Pseudopolyp, postinflammatory PTLD See Posttransplant lymphoproliferative disorder (PTLD) Pulse fluoroscope Pyogenic abscesses R Radiation enteritis Radiopaque surgical items Rapunzel syndrome Rectus sheath hematomas Recurrent hepatocellular carcinoma Recurrent pyogenic cholangitis Reflux esophagitis, on barium studies Renal angiomyolipoma Renal cell carcinoma (RCC) Retractile mesenteritis Retroperitoneal fibrosis (RPF) Retroperitoneal liposarcoma Retroperitoneal lymphadenopathy, low-density Retroperitoneum Richter hernia Rigler sign Ring down artifact Roux-en-Y gastric bypass surgery Ruptured aortic aneurysm S Sacculations Santorinicele Sarcoidosis manifestations of Scar endometriosis Schatzki ring Scleroderma See Progressive systemic sclerosis Sclerosing mesenteritis spectrum of Secretin Sentinel clot sign Serous microcystic cystadenomas Serum angiotensin-converting enzyme level Serum lipase level Sigmoid volvulus Sincalide Sleeve gastrectomy Slip ring artifacts Small bowel adhesions anorexia nervosa Ascaris closed loop obstruction diarrhea duodenal filling defect fluoroscopy gastrointestinal stromal tumors GI bleeding ileal carcinoid and calcified nodal metastasis intramural hemorrhage lisinopril lymphoid nodular hyperplasia Meckel diverticulum mesenteric ischemia metastases non-Hodgkin lymphoma pancreatic cancer radiation changes Roux-en-Y gastric bypass surgery scleroderma Small bowel follow-through (SBFT) Small-cell lung cancer (SCLC) Smoking, esophageal carcinoma Solid pseudopapillary tumor (SPT) Spigelian hernia Spleen AAST classification of angiosarcoma Candida species embolic disease hamartoma hemangioma Klippel-Trenaunay syndrome littoral cell angioma lymphoma metastases polysplenia portal hypertension rupture splenule Splenectomy Splenosis Splenules Steady-state free precession (SSFP) Stricture Subcapsular hematoma Sudeck point Sulfur colloid scan Superior mesenteric artery Superior vena cava (SVC) obstruction Suture needle Synthetic secretin T Tc-99m sulfur colloid scan Thrombophilia Todani classification Toxic megacolon Toxin B Transient erythema Transient hepatic intensity difference (THID) Transverse colon Traumatic diaphragmatic rupture Trichuris Trypanosoma cruzi Tuberous sclerosis Tuboovarian abscess (TOA) U Ulceration Ulcerative colitis vs Crohn disease Undescended testis V Varices, downhill Vascular embolization microcoil Vessel penetration sign von Hippel-Lindau (VHL) disease W Whipple procedure X X-ray detectable surgical objects Z Zenker diverticulum Zollinger-Ellison syndrome (ZES) ... J Roentgenol 20 11;197 (2) :W204–W 220 Silva AC, Evans JM, McCullough AE, et al MR imaging of hypervascular liver masses: a review of current techniques Radiographics 20 09 ;29 (2) :385–4 02 Answer D.This... Elsevier/Saunders, 20 14 :21 8 29 0 Silva AC, Evans JM, McCullough AE, et al MR imaging of hypervascular liver masses: a review of current techniques Radiographics 20 09 ;29 (2) :385–4 02 20b Answer C.The... pseudotumors Radiographics 20 09 ;29 (1) :21 1 22 9 Brancatelli G, Federle MP, Vilgrain V, et al Fibropolycystic liver disease: CT and MR imaging findings Radiographics 20 05 ;25 (3):659–670 16 Answer B.The