Mimics, Miscalls, and Misses in Koenraad J. Mortelé1

The radiologist plays a pivotal role in the detection and This chapter will summarize, review, and illustrate the characterization of pancreatic disorders. Unfortunately, the most common and important mimics, miscalls, and misses in accuracy of rendered diagnoses is not infrequently plagued by pancreatic imaging and thereby improve diagnostic accuracy a combination of “overcalls” of normal pancreatic anomalies of diagnoses rendered when interpreting radiologic studies of and variants; “miscalls” of specific and sometimes pathog- the . nomonic pancreatic entities; and “misses” of subtle, uncom- mon, or inadequately imaged pancreatic abnormalities. Ba- Normal Pancreatic Anatomy sic understanding of the normal and variant anatomy of the The Gland pancreas, knowledge of state-of-the-art pancreatic imaging The coarsely lobulated pancreas, typically measuring ap- techniques, and familiarity with the most commonly made mis- proximately 15–20 cm in length, is located in the retroperito- diagnoses and misses in pancreatic imaging is mandatory to neal anterior pararenal space and can be divided in four parts: avoid this group of errors. head and uncinate process, neck, body, and tail [4]. The head, neck, and body are retroperitoneal in location whereas the Mimics of pancreatic disease, caused by developmental tail extends into the peritoneal space. The pancreatic head is variants and anomalies, are commonly encountered on imag- defined as being to the right of the superior mesenteric vein ing studies [1–3]. To differentiate these benign “nontouch” en- (SMV). The uncinate process is the prolongation of the medi- tities from true pancreatic conditions, radiologists should be al and caudal parts of the head; it has a triangular shape with a familiar with them, the imaging techniques available to study straight or concave anteromedial border. The pancreatic neck them, and their variable imaging presentations [1–3]. Classic is located to the left of the head and ventral to the SMV. The examples include pseudomasses due to fetal lobulations, aber- pancreatic body and tail are situated behind the stomach, and rant ductal configurations, pancreatic clefts, and intrapancre- the distinction between them is not clearly defined but can be atic accessory spleens. determined using half of the distance between the neck and Miscalls of pancreatic abnormalities are generally multi- the end of the pancreatic tail [4]. There is a gradual decrease factorial and may be induced by lack of individual or general- of the size of the pancreas with age [5]. Moreover, the size of ized knowledge, inadequate imaging technique, and inaccu- the pancreas is variable. Therefore, overall proportions and rate interpretation due to overlapping or confusing features of features of the gland (including lobular architecture, symme- certain entities [1]. Classic examples include misdiagnosis of try, density and signal intensity, enhancement, normal duct, uneven pancreatic lipomatosis, determination of pancreatic and contour) are considered more important than absolute cancer resectability, characterization and accurate measure- measurements in assessing the presence of a focal or diffuse ment of cystic pancreatic lesions, and the misdiagnosis of pancreatic abnormality. autoimmune pancreatitis and inflammatory pseudotumors in chronic pancreatitis. The Ducts Misses of pancreatic disorders on imaging can typically The normal anteroposterior diameter of the main pancre- be classified as perceptual, technical, and communication re- atic duct measures maximally 3.5 mm in the head, 2.5 mm lated [1]. Classic examples include failed detection of small in the body, and 1.5 mm in the tail [2]. The main pancreatic (resectable) pancreatic cancers and subtle unresectable pancre- duct (MPD) receives approximately 20–30 side branches that atic malignancies, hypervascular pancreatic neoplasms, early enter the duct at right angles [6]. There are approximately 27 chronic pancreatitis, vascular complications in acute pancre- different normal ductal configurations, including the common atitis, and adenocarcinomas complicating intraductal papillary sigmoid configuration and the rare looped configuration. The mucinous tumor (IPMN). downstream ductal configuration most commonly (60%) en-

1Department of Radiology, Divisions of Abdominal Imaging and Clinical MRI, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Ansin 224, Boston, MA 02115. Address correspondence to K. J. Mortelé ([email protected]).

The Radiology M and M Meeting: Misinterpretations, Misses, and Mimics 1 Mortelé countered consists of a bifid configura- outpouchings of the parenchyma more Focal dilation of the terminal portion tion with patent ducts of Wirsung (ven- than 1.0 cm beyond the anterior superior of the dorsal duct, also called “Santorin- tral) and Santorini (dorsal) present (Fig. pancreaticoduodenal artery [7]. These icele, is suggestive of relative obstruc- 1). Less common configurations include lobulations are present in approximately tion at the minor papilla [8]. MRCP, es- a rudimentary duct of Santorini and a 30% of people and are classified in three pecially when enhanced by IV secretin, dominant duct of Santorini [2]. main types: type I (anterior), 10%; type has been shown to be highly accurate for II (posterior), 19%; and type III (later- depicting [9]. The Pancreatobiliary Union al), 5% [2, 3]. Another well-recognized The duct of Wirsung joins with the pseudomass is a prominence of the ante- Annular Pancreas common (CBD) and drains into rior and superior surface of the pancreat- Annular pancreas is a rare (1/2000) the through the major papilla ic body that abuts the posterior surface of congenital migratory anomaly due to [2, 3]. Before entering the duodenum, the the lesser omentum; this entity is known incomplete rotation of the ventral an- distal CBD and duct of Wirsung are en- as “tuber omentale” or “omental tuber- lage around the duodenum that leads to circled by the sphincter of Oddi, which osity” and should be not misinterpreted a segment of the pancreas encircling the typically measures 10–15 mm in length as a pancreatic neoplasm or lymph node second part of the duodenum [10]. There [2]. Sometimes, vivid contraction of the (Fig. 2) [2, 3]. are two types of annular pancreas: extra- sphincter of Oddi may simulate a stone mural and intramural. In the extramural in the distal CBD on MRCP; this has Ductal Fusion Anomalies type, the ventral pancreatic duct runs been referred to as the “pseudocalculus Discrepancy of the caliber of the MPD around the duodenum to join the main sign.” In most cases, the distal CBD and at the site of fusion of the dorsal and ven- pancreatic duct. In the intramural type, duct of Wirsung unite within the sphinc- tral ducts is a normal variant that may be the pancreatic tissue is intermingled ter of Oddi, forming a short (5 mm) com- confused for a site of stricturing [2]. The with muscle fibers in the duodenal wall mon channel with a distal dilation called absence of dilatation of the proximal or and small ducts drain directly into the the ampulla [2]. The duct of Santorini upstream ductal system enables differ- duodenum [2]. Annular pancreas can be drains the anterior and superior portions entiation between those entities (Fig. 3). diagnosed on the basis of CT and MRI of the head via the minor papilla. Duplication of the pancreatic ductal sys- findings that reveal pancreatic tissue and tem is fairly common, especially in the an annular duct encircling the descend- Classic Variants (Mimics) to Know tail, whereas parenchymal duplication is ing duodenum [11]. Pancreatic Fetal Lobulations extremely rare. Pancreatic shape alterations can simu- Pancreas divisum is reported in ap- Pancreatic Hypoplasia late pancreatic neoplasms. Pancreatic proximately 9% of the population [7] Hypoplasia (partial agenesis) results head and neck lobulations are defined as and results from nonfusion of the ven- from the absence of the ventral or, more tral and dorsal pancreatic ducts during commonly, the dorsal anlage. Hypoplasia embryologic life [8]. The ventral duct of the dorsal anlage, also known as “short (duct of Wirsung) drains only the ventral or truncated pancreas,” can be partial or anlage, whereas most of the gland (dor- complete and may be seen as a solitary sal anlage) drains via the minor papilla finding or in association with heterotax- through the dorsal duct or duct of Santo- ia syndromes [12]. Patients with dorsal rini [8] (Fig. 4). pancreatic agenesis often present with

Fig. 1—Oblique coronal thick-slab MRCP image obtained in asymptomatic 39-year-old A B man shows normal bifid ductal configuration Fig. 2—43-year-old woman with ampullary adenocarcinoma. with duct of Wirsung (long arrow) and duct of A and B, Axial (A) and coronal (B) contrast-enhanced CT images show outpouching of pancreatic Santorini (short arrow). body in lesser sac (arrow). This omental tuberosity should not be confused with lymph node.

2 The Radiology M and M Meeting: Misinterpretations, Misses, and Mimics Imaging Pancreatic Disease

ter of Oddi with formation of a long common channel (usually > 15 mm) [14]. This long common channel allows reflux of pancreatic secretions into the biliary system, possibly resulting in choledochal web and cyst formation. Conversely, re- flux of bile into the pancreatic duct can cause acute recurrent pancreatitis. Top Five Miscalls to Avoid Fig. 3—Oblique coronal thick-slab MRCP Calling Uneven Pancreatic image obtained in asymptomatic 26-year-old Lipomatosis Pancreatic Cancer woman shows discrepancy of caliber of main Fig. 4—Oblique coronal thick-slab MRCP Diffuse pancreatic lipomatosis can pancreatic duct at site of fusion of dorsal image obtained in 47-year-old woman with and ventral ducts (long arrow). This is normal acute recurrent pancreatitis shows pancreas be seen in cystic fibrosis; Shwachman- variant that may be confused with site of divisum characterized by lack of fusion of dorsal Diamond syndrome; diabetic, obese, structuring. Also note looping of pancreatic (long arrow) and ventral (short arrow) ducts. and elderly patients; or with chronic duct (short arrow). Dorsal duct is mildly dilated with presence of Santorinicele at minor papilla. steroid intake [15]. Sometimes, fatty replacement is heterogeneous through- nonspecific abdominal pain or diabetes people [13]. Their location is vari- out the gland. Focal fatty change of the mellitus. When the diagnosis of pancre- able, with few (< 2%) located within anterior portion of the pancreatic head atic hypoplasia is suspected, it is critical the pancreatic tail [13]. Therefore, an only is not rare on CT studies and can to rule out a pancreatic neoplasm with accessory spleen may mimic a hyper- be confused with a hypodense mass upstream atrophy of the gland. vascular pancreatic mass. Accessory [15]. MRI, with in- and out-of-phase spleens, however, typically have the imaging, can exclude a true mass by Pancreatic Cleft same density or signal intensity char- showing the presence of intracellular Peripancreatic fat can invaginate into acteristics as the main spleen on CT or fat (Fig. 6). There are four different rec- the pancreas and produce an appear- MRI, respectively (Fig. 5). In addition, ognized types of uneven pancreatic li- ance that is similar to a cleft. Such a they enhance to the same degree as the pomatosis: Type 1a (35%) defines fatty pattern on CT in a trauma patient can spleen on both modalities. However, if change of the head with sparing of the be confused with a pancreatic fracture. CT and MRI findings are still equivo- ventral pancreas and the peribiliary re- However, serum pancreatic enzyme cal, then nuclear scintigraphy can be gion; type 1b (36%) is replacement of levels are usually normal and the peri- performed with either 99mTc-labeled the head, neck, and body with sparing pancreatic fat remains clear, which typ- sulfur colloid or 99mTc-labeled heat- of the ventral pancreas and the peribili- ically excludes the presence of severe damaged RBCs. ary region; type 2a (12%) is replace- pancreatic trauma. ment of the head, including the ventral Anomalous Pancreatobiliary Union pancreas and sparing of the peribiliary Intrapancreatic Accessory Spleen An anomalous pancreatobiliary junc- region; and type 2b (18%) is the total Accessory spleens are common, tion is characterized by fusion of the pan- replacement of the gland, only sparing occurring in approximately 15% of creatic duct and CBD outside the sphinc- the peribiliary region [15].

A B C Fig. 5—37-year-old man evaluated for abdominal pain. A–C, Diffusion-weighted A( ), T1-weighted (B), and gadolinium-enhanced fat-suppressed T1-weighted (C) images show 1.2-cm pancreatic tail mass (arrow). Lesion has same signal characteristics as main spleen on all sequences. In addition, it enhances to same degree as spleen. These features are diagnostic of accessory spleen.

The Radiology M and M Meeting: Misinterpretations, Misses, and Mimics 3 Mortelé

of measurement discrepancies greater than 5 mm decreased from 35.4% to 17.4%, and measurement discrepan- cies less than 10 mm decreased from 17.3% to 3.4%. Therefore, we believe it is fair to conclude that introduction of a few measurement standards can significantly reduce interobserver vari- ability in the measurement of pancreatic cystic lesions and may prevent errone- A B ous reporting of growth or unwarranted changes in management.

Rendering Pancreatic Cancer Resectable When It Is Not Ductal pancreatic adenocarcinoma, the fourth to fifth leading cause of can- cer death in the Western hemisphere, accounts for nearly 95% of all malig- nant pancreatic neoplasms. At the time of clinical presentation, 65% of patients C D with pancreatic cancer have locally ad- Fig. 6—65-year-old man evaluated for pancreatic lesion seen on prior CT study. A and B, T2-weighted (A) and gadolinium-enhanced fat-suppressed T1-weighted (B) images show vanced tumors, with metastatic disease 2.3-cm pancreatic head mass (arrow). present in approximately 85% of cases C and D, Axial T1-weighted (C) and out-of-phase (D) MR images show signal drop (arrow) in anterior [19]. With this information in mind, one pancreatic head consistent with chemical shift effect due to presence of fat (uneven lipomatosis). has to realize that focusing on unre- sectability rather than resectability will Measuring Cystic Pancreatic are often pleomorphic in shape and the benefit the patient by avoiding useless Lesions Inaccurately apparent size can vary significantly de- and morbid surgery in unresectable cas- Cystic pancreatic lesions are common. pending on the imaging modality, plane es. Too often, the evaluation of staging At my institution, Lee et al. [16] reported of imaging, and pulse sequence used. imaging studies of patients with pan- the prevalence of incidental pancreatic Therefore, inaccurate measurements creatic adenocarcinoma is focused on cystic lesions detected on MRI to be on could lead to erroneous reporting of the possible resectability of pancreatic the order of 13.5%. Importantly, most growth or unwarranted changes in man- adenocarcinoma, with elaborate evalu- cystic pancreatic lesions are neoplastic agement. Because currently none of the ation of the peripancreatic vascular epithelial lesions and only a few of the commonly used guidelines include stan- structures and their relationship to the lesions are pseudocysts, related to acute dards for measurement, it is of utmost tumor while small hepatic, omental, and or chronic pancreatitis, or nonneoplastic importance to measure cystic pancreatic peritoneal metastases are overlooked in epithelial cysts. The size of the lesion lesions accurately and consistently in a the process (Fig. 7). at first diagnosis is an important factor departmentally agreed fashion and be in determining the probability of malig- aware of the pitfalls of intermodality and Calling Autoimmune Pancreatitis nancy: If a lesion measures less than 3 interobserver variability. Pancreatic Cancer cm, the likelihood of malignancy at that In an institutional review board–ap- Since its first description by Yoshida time, regardless of the underlying histo- proved HIPAA-compliant study at our et al. [20] in 1995, autoimmune pan- logic composition, is less than 3% [17]. institution (Dunn D et al., 2013, un- creatitis has been increasingly recog- Therefore, most of these smaller lesions published data), 144 MRI examina- nized as a rare (5%) but global cause of are not resected but are followed longi- tions containing an even distribution chronic pancreatitis [21]. Autoimmune tudinally with imaging. Several societ- of pancreatic cysts measuring between pancreatitis refers to a chronic inflam- ies, including the American College of 5 and 35 mm were reviewed by four matory condition mediated by an auto- Radiology, have proposed guidelines for observers before and after (12 weeks) immune mechanism consisting of lym- the follow-up and management of small introduction of measurement standards. phocytes and plasma cells. It can involve incidental cystic pancreatic lesions [18] The interobserver agreement (kappa) the pancreas focally or diffusely (Fig. 8). on the basis of single-length measure- increased significantly from 0.41 to Although autoimmune pancreatitis oc- ment, growth, imaging characteristics, 0.67 after introduction of measurement curs in both sexes, it is most prevalent and symptoms. However, these lesions standards. In addition, the frequency in men over the age of 50 years. Auto-

4 The Radiology M and M Meeting: Misinterpretations, Misses, and Mimics Imaging Pancreatic Disease

A B C Fig. 7—67-year-old woman with back pain and weight loss. A, Axial contrast-enhanced CT image shows small pancreatic head mass (arrow). Assessment of local extent failed to show vascular invasion. B and C, Axial contrast-enhanced CT images obtained slightly higher (B) and lower (C) than A show subcentimeter metastases (arrow) adjacent to liver capsule and omentum, rendering this patient unresectable.

A B C Fig. 8—17-year-old boy evaluated for chronic abdominal pain for over 5 years. A and B, T2-weighted (A) and fat-suppressed T1-weighted (B) images show 5-cm pancreatic tail abnormality (arrow). IgG4 immunostaining was performed on peripapillary biopsies and IgG4-expressing plasma cells were noted, consistent with autoimmune pancreatitis. C, Follow-up axial T2-weighted MR image obtained after 6-week trial of steroids shows near-complete resolution of abnormality (arrow). immune pancreatitis has been associated and their increasingly frequent recogni- sis via a combination of clinical in- with other autoimmune diseases, includ- tion make it essential that the practicing formation, imaging, and endoscopic ing Sjögren syndrome, retroperitoneal radiologist be aware of their existence ultrasound with cyst fluid analysis is of fibrosis, primary sclerosing cholangitis, and manifestations. utmost importance. Cystic pancreatic rheumatoid arthritis, and inflammatory neoplasms themselves are a diverse bowel disease. A relatively new and un- Calling “Nontouch” Cystic Pancreatic group of tumors that vary in aggres- common diagnosis, autoimmune pancre- Lesions “Surgical” and Vice-Versa siveness from benign to dysplastic or atitis, or systemic IgG4-associated scle- Because most cystic pancreatic le- premalignant to frankly invasive can- rotic disease, is not often recognized on sions are neoplastic, accurate diagno- cers [22]. Because treatment and man- initial presentation and is misdiagnosed as a pancreatic malignancy. Of all Whip- ple procedures performed in the United States, autoimmune pancreatitis is the most common benign entity unexpect- edly found. Accurate diagnosis is, there- fore, essential because this entity can be effectively managed noninvasively with the use of corticosteroids [21]. Surgery is not indicated in the treatment of this condition, and the prognosis for both pancreatic and extrapancreatic manifes- A B tations is generally favorable with medi- Fig. 9—17-year-old girl evaluated for abdominal pain. cal management alone. The evolving A and B, T2-weighted (A) and T1-weighted (B) images show 3-cm pancreatic tail encapsulated cystic mass (arrow) with layering blood products. Combination of presence of capsule and definition of autoimmune pancreatitis hemorrhage in cystic mass in young girl highly suggests solid pseudopapillary tumor of pancreas, and IgG4-associated sclerotic disease which is surgical lesion. Subsequent resection confirmed presumptive diagnosis.

The Radiology M and M Meeting: Misinterpretations, Misses, and Mimics 5 Mortelé agement of specific cystic pancreatic Detection of Hypervascular tocol, radiologists should look, from a tumors are markedly different on the Pancreatic Lesions ductal perspective, for changes that are basis of histopathologic subtype, fa- One of the challenges pancreatic im- induced by periductal fibrosis and the miliarity with the imaging appearances aging still faces is to detect small hy- resultant duct ectasia. These changes, of these tumors is of utmost importance pervascular tumors, such as pancreatic including side-branch abnormalities, to help guide management and prevent endocrine tumors and hypervascular me- main duct dilation and strictures, or unnecessary surgical interventions tastases from primary tumors, such as presence of intraductal stone and in- (Fig. 9). Fortunately, many, especially renal cell carcinoma. On multiphasic traparenchymal cyst formation can be when large, have specific imaging and contrast-enhanced CT and MRI, hyper- graded using the Cambridge classifi- demographic features that enable dif- vascular lesions are best seen, and not cation. In addition to evaluating the ferentiation from one another. Essential infrequently only seen, in the late arte- ductal changes, MRI is also sensitive imaging features to evaluate include rial phase after contrast administration for detecting parenchymal abnormali- presence of a capsule, presence of in- [24]. An optimized technique coupled ties [26]. What radiologists specifically tralesional hemorrhage, presence of with increased suspicion in certain clini- should look for is subtle signal intensity communication with the main pancre- cal scenarios will undoubtedly improve decreases within the gland, especially atic duct, lesion contour, presence and detection (Fig. 11). More recently, dif- on fat-suppressed T1-weighted im- location of calcifications, and lesion fusion-weighted imaging has been pro- ages. Another important conventional vascularity [22]. posed as a beneficial method to improve MRI feature of chronic pancreatitis is pancreatic endocrine tumor detection. delayed and diminished enhancement Top Five Misses to Avoid of the gland after gadolinium chelates A recent internal review of our depart- Diagnosis of Early Chronic Pancreatitis administration. It is very important to mental quality assurance and peer-re- Chronic pancreatitis leads to irre- realize that these parenchymal abnor- view databases was performed and high- versible parenchymal and ductal chang- malities may precede any ductal abnor- lighted the type of errors encountered es in the pancreas. MRI may enable an malities (Fig. 12). in pancreatic imaging at our institution early diagnosis of chronic pancreatitis (Table 1). Most (approximately 50%) so patients can be given treatment op- Detection of Vascular Complications misses were perceptual false-negative tions that may prevent progression [25]. in Acute Pancreatitis readings (true misses) followed by miss- MRI is highly sensitive and specific for Pseudoaneurysm formation occurs in es because of technical errors (wrong the diagnosis of chronic pancreatitis in approximately 10% of cases of pancre- protocol, technical failure). Review of patients with advanced disease. When atitis [27].The time interval is variable, the individual cases classified most - er applying a standard MRI/MRCP pro- ranging from days to several years after rors as one of the following. TABLE 1: Types of Radiologic Errors Related to Pancreas as Submitted to Detection of Small (Resectable) Quality Assurance (QA) Database and Through Peer Review at Beth Pancreatic Cancers Israel Deaconess Medical Center Ductal pancreatic adenocarcinoma is Radiologic Error QA Database (n = 91) Peer Review (n = 23) the fourth to fifth leading cause of cancer death in the Western hemisphere and has Perceptual a devastating prognosis unless detected Technical 2 (2) when small and resectable [19]. When False-negative (true miss) 37 (41) 13 (57) the correct protocol is used, the newer Interpretive MDCT and MRI scanners result in ac- False-positive 3 (3) curacies of 96% for detecting pancreatic Misclassification 10 (11) 9 (39) cancer. Maximum tumor conspicuity can be achieved during the late arterial Communication or pancreatic parenchymal (40 seconds Input 2 (2) after contrast administration) phase of a Output (report) 2 (2) 1 (4) dynamic contrast-enhanced CT or MRI Procedural examination [23]. Probably more impor- Complications 4 (4) tant, it is essential to screen the pancreas Nonrelated 1 (1) for small lesions on all cross-sectional Technical studies obtained for other indications. Incidental detection of a small pancreat- Protocol (radiologist) 11 (12) ic cancer may allow complete resection Study (technologist) 19 (21) (R0) and improved survival (Fig. 10). Note—Data are number with percentage in parentheses.

6 The Radiology M and M Meeting: Misinterpretations, Misses, and Mimics Imaging Pancreatic Disease the acute inflammatory event. The ves- ies. Early detection and management occur into the peritoneum, adjacent hol- sels most commonly affected include are paramount given the high mortality low organs, pseudocyst, or pancreatic the gastroduodenal and splenic arter- associated with rupture. The latter can duct (also known as hemosuccus pan- creaticus) (Fig. 13). Dedicated MDCT or MR angiography can elegantly depict the pseudoaneurysm as a well-delineat- ed rounded structure originating from the donor artery [27]. High-attenuation or high-signal-intensity thrombus may be seen within the aneurysm on unen- hanced CT scans and fat-suppressed T1-weighted MR images. After contrast administration, the aneurysm may fill with contrast material if it is not com- A B pletely thrombosed.

Diagnosing Pancreatic Cancer in Intraductal Papillary Mucinous Tumor The 5-year risk of malignancy in main duct IPMN is 63% but only 15% in isolated side-branch IPMN. Suggested risk factors for malignancy on imaging include main duct dilation more than 10 mm in width, increasing size and complexity of side-branch lesions, side- C D branch lesions measuring more than 3 Fig. 10—62-year-old woman who was evaluated in emergency department after motor vehicle accident. cm in size, presence of internal calcifica- A and B, Axial contrast-enhanced CT images show small pancreatic body mass (arrow, A) that was tions, CBD dilatation, thick septations, missed. Large left hepatic lobe hematoma was identified. C and D, Axial contrast-enhanced CT images obtained 1 year after A and B because of epigastric or mural nodules [22]. Familiarity with pain show unresectable pancreatic body cancer (arrow, D) with multiple liver metastases. these features may enable detection of

Fig. 11—57-year-old woman who underwent left nephrectomy 7 years ago for renal cell carcinoma (RCC). A and B, Axial (A) and coronal (B) contrast- enhanced CT images show small pancreatic head metastasis (arrow) that was missed, although present, on 12 consecutive torso CT scans. Awareness of possible spread of RCC to pancreas and specific screening of gland for small hypervascular lesions probably could have avoided this error. A B

Fig. 12—40-year-old woman with chronic abdominal pain. A, Oblique coronal MRCP image shows normal pancreatic duct. B, Axial fat-suppressed T1-weighted image shows atrophy of pancreas (arrows) and decreased signal intensity due to chronic pancreatitis. A B

The Radiology M and M Meeting: Misinterpretations, Misses, and Mimics 7 Mortelé

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8 The Radiology M and M Meeting: Misinterpretations, Misses, and Mimics