Solitary Fibrous Tumor of the Pancreas: Imaging Findings

We report here a case of a pathologically proven solitary fibrous tumor of the pancreas. A 54-year-old man was referred to our hospital for further evaluation of a pancreatic mass that was found incidentally. CT, MR imaging, and endoscopic ultrasonography showed a well-defined, enhancing mass with cystic portions of the pancreas body. MR cholangiopancreatography showed no pancreatic duct dilatation. A solitary fibrous tumor of the pancreas is a very rare lesion.

Extramedullary Plasmacytoma of the Pancreas: Imaging Findings: Case Report

Extramedullary plasmacytoma involves organs outside the bone marrow, but involvement of the pancreas is very rare. We present the imaging findings of extramedullary plasmacytoma of the pancreas in a patient with multiple myeloma. Mixed echogenecity was noted at US, and marked enhancement at CT and MR.

Differential Diagnosis of Benign and Malignant Intraductal Papillary Mucinous Tumors of the Pancreas: MR Cholangiopancreatography and MR Angiography

OBJECTIVE: To compare the usefulness of magnetic resonance cholangiopancreatography (MRCP) and MR angiography (MRA) in differentiating malignant from benign intraductal papillary mucinous tumors of the pancreas (IPMTs), and to determine the findings which suggest malignancy. MATERIALS AND METHODS: During a 6-year period, 46 patients with IPMT underwent MRCP. Morphologically, tumor type was classified as main duct, branch duct, or combined. The diameter of the main pancreatic duct (MPD), the extent of the dilated MPD, and the location and size of the cystic lesion, septum, and communicating channel were assessed. For all types of IPMTs, enhanced mural nodules and portal vein narrowing were evaluated at MRA. RESULTS: Combined-type IPMTs were more frequently malignant (78%) than benign (42%) (p < 0.05). Compared with benign lesions, malignant lesions were larger, and the caliber of the communicating channel was also larger (p < 0.05). Their dilated MPD was more extensive and of greater diameter (p < 0.05), and the presence of mural nodules was more frequent (p < 0.001). CONCLUSION: Combined MRCP and MRA might be useful for the differential diagnosis of malignant and benign IPMTs of the pancreas.

Mixed Microcystic and Macrocystic Serous Cystadenoma of the Pancreas: A Case Report

Serous cystadenomas of the pancreas are generally considered to be microcystic adenomas. Typical serous cystadenomas of the pancreas are encapsulated tumors composed of tiny cysts less than 2 cm in size showing sponge-like appearance with a central stellate scar or calcification on the cross-section. It has been recently reported, however, that serous cystadenomas may have macrocystic variants (major cysts more than 2 cm in size) that are radiologically indistinguishable from mucinous cystadenomas of the pancreas. We report the CT and MR imaging findings in a patient with mixed microcystic and macrocystic serous cystadenoma of the pancreas, indicating the histopathologic correlation. The mass was composed of two different types of cyst: multiple, small (2 cm) with peripheral calcification.

Radiologic Findings of the Serous Cystadenomas of the Pancreas with Macro cystic or Unilocular Variants: Comparison with the Pathologic Findings

PURPOSE: To evaluate the radiologic findings of the serous cystadenomas of the pancreas with macrocystic or unilocular variants and to compare them with the pathologic findings. MATERIALS AND METHODS: In eight patients(7 females and 1 male ranging in age from 26 to 49 [mean, 37] years) with surgically proven serous cystadenomas, the findings of abdominal CT(n=8), abdominal sonography(US, n=8), endoscopic retrograde pancreatography(ERCP, n=6), endoscopic sonography(EUS, n=3), and MRI(n=1) were evaluated. The location and size of tumors, lobulation, internal septa, solid component, calcification, communication with the pancreatic duct, dilatation of the proximal pancreatic duct, and contrast enhancement on CT were assessed and compared with the pathologic findings. RESULTS: Tumors were located in the head(n=3), body(n=3) and tail(n=2), and their mean size was 4 (range, 1 -8) cm. Abdominal CT scanning revealed well-defined cystic masses composed of macrocyst(s) with calcifica-tion(n=3) and dilatation of the proximal duct (n=2). Three cases showed contrast enhancement of the cystic walls, the pathologic examination of which revealed fibrotic tissues. Four tumeurs were unilocular without septation or lobulation; these features, together with calcification, were depicted more clearly by US and EUS. ERCP revealed no communication between the cysts and pancreatic ducts. Imaging studies showed that macrocystic adenomas were superimposed on mucinous cystadenomas, and unilocular adenomas were indis-tinguishable from pseudocysts. CONCLUSION: Serous cystadenomas of the pancreas with macrocystic or unilocular variants are common in middle-aged women. Features present due to the existence of fibrotic tissues, and which may be reveled by contrast-enhanced CT, include internal septa, calcification, duct dilation, and prominent enhancement of the cystic wall. Serous cystadenoma should be included in the differential diagnosis of macrocystic or unilocular cystic lesions of the pancreas.

Diagnosis of Pancreatic Tumors: Comparison of MR Pancreatograp hy (MRP )and Endoscopic Retrograde Pancreatography(ERP)

PURPOSE: Magnetic resonance pancreatography(MRP) is a non-invasive imaging technique for visualization of the pancreatic duct system, and is similar to those obtained by means of endoscopic retrograde pancreatography (ERP). To determine the role of MRP in the diagnosis of pancreatic tumors, the diagnostic confidence and imaginal difference of MRP and ERP were compared. MATERIALS AND METHODS: Twenty patients (13 male and 7 female, mean age 59 years) with pancreatic tumors underwent MRP and ERP. The former involved the use of a single shot fast spinecho sequence on a 1.5T system. All images were retrospectively reviewed by a radiologist and a gastroenterologist, working together. Both MRP and ERP were compared for separate visualization of the head, body and tail portion of the pancreatic duct, and scored as excellent (4), good (3), fair (2), poor (1), or no visualization (0). In addition, the overall diagnostic confidence of both modalities was graded subjectively from non-diagnoses (0) to definite information (4). The final diagnoses derived from surgical findings (n=9) or imaging findings and clinical follow-up (n=7) were as follows : pancreatic cancer (n=12), mucin-producing pancreatic cancer (n=2), mucinous ductectatic tumor (n=4), serous cystadenoma (n=2). To assess the statistical significance of difference, the paired t-test was used. RESULTS: Mean scores of visualization of the pancreatic duct by MRP and ERP were 2.91 and 3.15 in the pancreatic head (p=NS), 3.11 and 2.18 in the pancreatic body (p=NS), and 3.07 and 1.09 in the pancreatic tail (p<0.01). The mean score of diagnostic confidence was 4.03 for MRP and 2.51 for ERP, a statistically significant difference (p <0.05). In 11 patients with obstruction of the pancreatic duct due to malignant lesions, MRP visualized the duct both proximally and distally to the site of obstruction, while ERP visualized only the distal duct to the site of obstruction. MRP was also better at defining the extent of tumor by visualization of surrounding pancreatic parenchyma. In two cases of serous cystadenoma with lack of communication between the pancreatic duct and cystic neoplasm, MRP depicted the lesion clearly whereas ERP showed no information. CONCLUSION: MRP is better than ERP at visualizing the of pancreatic duct proximal to obstruction, assessment of tumoral extent, and diagnosis of a cystic neoplasm which does not communicate with the pancreatic duct.

MRI of Normal Pancreas: Comparison of T2-Weighted Pulse Sequences Using Turbo Spin Echo, Turbo Spin Echo with Fat Suppression, HASTE and HASTE with Fat Suppression

PURPOSE: To compare various breath-hold T2 weighted sequences in imaging normal pancreas with a phased-arraycoil. MATERIALS AND METHODS: Eighteen patients without pancreatic disease were studied with breath-hold turbo spinecho (TSE) (TR/TE/ETL, 3500/138/29), TSE with fat suppression (FS-TSE), half-Fourier acquisition single-shot turbospin echo (HASTE) (TE/ETL, 87/128) and HASTE with fat suppression (FS-HASTE) at 1.0T magnet strength and using aphased-array coil. Signal difference-to-noise ratio (SD/N) between the pancreas and peripancreatic fat wasmeasured ; the delineation of the pancreatic border and pancreatic duct, and the amount of artifact were evaluatedby two radiologists who reached a consensus. RESULTS: HASTE showed a higher SD/N than TSE or FS-HASTE (p < 0.01),TSE was superior to FS- TSE or HASTE in the delineation of pancreatic border(p < 0.001). HASTE was superior to TSEin the delineation of pancreatic duct(p < 0.001). TSE showed more artifacts than FS-TSE(p < 0.001) ; HASTE andFS-HASTE showed no artifact. CONCLUSION: TSE is better than HASTE for the delineation of pancreatic margin but HASTE shows less artifacts and a more conspicuous pancreatic duct. Fat suppression decreases artifacts but makes the pancreatic margin indistinct.

MRCP Using Breath-hold HASTE Sequence: Comparison of Maximum Intensity Projection Image with Single Slice Acquisition Image

PURPOSE: To compare the usefulness of single-slice acquisition imaging and conventional maximum intensity projection imaging, as employed in magnetic resonance cholangiopancreatography (MRCP) using the Half-Fourier Acquisition Single Shot Turbo Spin-Echo(HASTE) sequence. MATERIALS AND METHODS: Five healthy volunteers underwent MRCP using the HASTE sequence on a 1.5T MR unit. Two data acquisition techniques were used : 1) single slice acquisition, with 20 mm slice thickness (imaging time, 2 sec), 2) multi-slice acquisition, with 5 mm slice thickness (imaging time, 19 sec), followed by maximum intensity projection reconstruction. Two radiologists independently evaluated the MRCP images obtained using these two techniques; based on the depiction by each of ten anatomic structures, their quality was graded as excellent (3 points), good (2 points), fair(1 point) or poor(0). Mean scores were totalled, and to compare the quality of the two techniques, these scores were compared. Data was statistically analyzed using the paired student t-test. RESULTS: There was no difference in bile duct image quality between the two techniques. The pancreatic duct was more conspicuous on single-slice (mean score, 1.94) than on maximum intensity projection imaging (mean score, 0.7). The sum of the mean scores of single-slice imaging was 18.75, and that of maximum intensity projection imaging was 14.7 (p=0.42); the general difference between the two techniques was thus statistically insignificant. CONCLUSION: Compared with maximum intensity projection imaging, single-slice imaging had a distinct advantage : acquisition time was short (within 2 sec), thus motion artifacts could be avoided, and there was no need for post-processing. There is a close and direct connection between the avoidance of motion artifact and short acquisition time, but lack of need for post-processing is independent. On single-slice images, the pancreatic duct was more conspicuous than on maximum intensity projection images. The former can therefore be used with patients who experience respiratory difficulty or are suspected to be suffering from disease of the pancreotic duct.

MR Cholangiopancreatography: Comparison of Breath-hold Fast Spin Echo and Respiratory Triggered Fast Spin Echo Techniques

PURPOSE: To determine relative image qualities and to evaluate their ability to visualize biliary trees and pancreatic ducts, we compared the breath-hold fast spin echo (FSE) and respiratory triggered FSE technique in magnetic resonance cholangiopancreatography (MRCP). MATERIALS AND METHODS: Forty-seven patients with suspected of hepatic disease but no pancreatic or biliary ductal dilatation, as determined by other imaging techniques('group of pathologic pancreatobiliary tree') underwent MRCP. Heavily T2-weighted FSE coronal images were obtained by both breath-hold and respiratory triggered techniques. These two images were 3D-reconstructed using a maximal intensity projection algorithm. Three radiologists scored the image qualities of anatomic structures in each set of image, then directly compared the image quality of the images obtained by the two techniques. RESULTS: For the visualization of common hepatic ducts and common bile dvcts, FSE MRCP images obtained using the respiratory-triggered technique were triggered technique were significantly better than those obtained using the breath-hold technique (P<0.05). Fifty-nine to 88% of breath-hold images of the biliary tree and 63-95% of respiratory triggered images were optimal. For the pancreatic duct, however, 24% of breath-hold images and 15% of respiratory-triggered images provided optimal image quality. In direct comparison, respiratory triggered images were better in 25 cases (52.1%), both images were comparable in 12 cases (25.0%), and in 11 cases (22.9%), breath-hold images were better. These differences were statistically significant (p<0.05). CONCLUSION: For the vizualization of extrahepatic bile ducts, the respiratory triggered FSE sequence was better than the breath-hold sequence; for the evaluation of both a non-dilated and dilated pancreatobiliary system, however, both techniques need further development.

MR of Normal Pancreas: Comparison of Five Pulse Sequences and Enhancing Patterns on Dynamic Imaging

PURPOSE: To compare T1-weighted FLASH and turbo spin echo (SE) T2-weighted sequences with conventional T1-and T2-weighted sequences in imaging normal pancreas and to describe the enhancing patterns on dynamic MR imging. MATERIALS AND METHODS: Forty-four patients with presumed hepatic hemangiomas were studied at 1.0T or 1.5T by using conventional SE sequences (T1-weighted, T2-weighted, and heavily T2-weighted), turbo-SE T2-weighted sequences, and breath-hold T1-weighted FLASH sequences acquired before, immediately on, and at 1, 2, 3, and 5 or10 minutes after injection of a bolus of gadopentetate dimeglumine. No patients had either a history or its clinical features of pancreatic disease. Images were quantitatively analyzed for signal-difference-to noise ratios(SD/Ns) between the pancreas and peripancreatic fat. Percentage enhancement of the pancreas was measured on each dynamic MR image. Conspicuity of the pancreatic border was qualitatively evaluated according to a consensus, reached by three radiologists. RESULTS: Turbo-SE T2-weighted images had a significantly higher SD/N ratio(p<0.001) and better conspicuity of the pancreatic border (p<0.001 ) than SE T2- and heavily T2-weighted images ; T1-weighted SE images had a significantly higher SD/N ratio than T1-weighted FLASH images (p<0.001), but there was no significant difference between them in qualitative analysis (p=0.346). Percentage enhancement immediately on and at 1, 2, 3, 5, and 10 minutes after administration of contrast material was 39.9%, 44.5%, 42.9%, 40.8%, 36.3%, 29.9%, respectively, with peak enhancement at 1 minute. CONCLUSION: In MR imaging of normal pancreas, turbo-SE T2-weighted imaging is superior to SE T2- and heavily T2-weighted imaging, and SE T1-weighted imaging is superior to T1-weighted FLASH imaging. On serial gadolinium-enhanced FLASH imaging, normal pancreas shows peak enhancementat 1 minute.

MR of Normal Pancreas: Comparison of Five Pulse Sequences and Enhancing Patterns on Dynamic Imaging

PURPOSE: To compare T1-weighted FLASH and turbo spin echo (SE) T2-weighted sequences with conventional T1-and T2-weighted sequences in imaging normal pancreas and to describe the enhancing patterns on dynamic MR imging. MATERIALS AND METHODS: Forty-four patients with presumed hepatic hemangiomas were studied at 1.0T or 1.5T by using conventional SE sequences (T1-weighted, T2-weighted, and heavily T2-weighted), turbo-SE T2-weighted sequences, and breath-hold T1-weighted FLASH sequences acquired before, immediately on, and at 1, 2, 3, and 5 or10 minutes after injection of a bolus of gadopentetate dimeglumine. No patients had either a history or its clinical features of pancreatic disease. Images were quantitatively analyzed for signal-difference-to noise ratios(SD/Ns) between the pancreas and peripancreatic fat. Percentage enhancement of the pancreas was measured on each dynamic MR image. Conspicuity of the pancreatic border was qualitatively evaluated according to a consensus, reached by three radiologists. RESULTS: Turbo-SE T2-weighted images had a significantly higher SD/N ratio(p<0.001) and better conspicuity of the pancreatic border (p<0.001 ) than SE T2- and heavily T2-weighted images ; T1-weighted SE images had a significantly higher SD/N ratio than T1-weighted FLASH images (p<0.001), but there was no significant difference between them in qualitative analysis (p=0.346). Percentage enhancement immediately on and at 1, 2, 3, 5, and 10 minutes after administration of contrast material was 39.9%, 44.5%, 42.9%, 40.8%, 36.3%, 29.9%, respectively, with peak enhancement at 1 minute. CONCLUSION: In MR imaging of normal pancreas, turbo-SE T2-weighted imaging is superior to SE T2- and heavily T2-weighted imaging, and SE T1-weighted imaging is superior to T1-weighted FLASH imaging. On serial gadolinium-enhanced FLASH imaging, normal pancreas shows peak enhancementat 1 minute.