Solid-pseudopapillary tumor of the pancreas: MR imaging findings in 21 patients

PurposeSolid-pseudopapillary tumor (SPT) of the pancreas is a rare, low-grade malignancy, which mostly occurs in adolescent and young adult females. The goal of this study was to retrospectively analyze the magnetic resonance (MR) imaging presentation of SPT of the pancreas.MethodsWe retrospectively reviewed the preoperative MR imaging examinations and the medical, surgical and histopathological records of 21 patients who underwent surgery for SPT of the pancreas. MR imaging included T1-weighted, T2-weighted, and gadolinium chelate-enhanced MR imaging. In addition, 10 patients had diffusion-weighted (DW) MR imaging. MR examinations were retrospectively reviewed for location, size, morphological features and signal intensity of the tumors.ResultsNineteen women and 2 men (median age, 23 years; range, 14–59) were included. Seven patients (7/21; 33%) presented with abdominal symptoms. The median largest tumor diameter was 53mm (range, 32–141 mm). SPTs were located in the pancreatic head, body, and tail in 9 (9/21; 43%), 5 (5/21; 24%) and 7 (7/21, 33%) patients, respectively. All patients (21/21; 100%) had a single SPT. SPTs were more frequently oval (12/21; 57%), predominantly solid (12/21; 57%), fully encapsulated (16/21; 76%), larger than 30 mm (21/21; 100%), hypointense on T1-weighted MR images (21/21, 100%), hyperintense on T2-weighted MR images (21/21; 100%) and with an enhancing capsule after gadolinium-chelate administration (21/21; 100%).ConclusionsThere is trend of appearance for SPT of the pancreas on MR imaging but that variations may be observed in a number of cases. SPT uniformly presents as a single, well-demarcated and encapsulated pancreatic mass.     

Pancreatic changes in primary sclerosing cholangitis: evaluation with MR imaging

OBJECTIVE: The purpose of this study was to determine the frequency and the spectrum of MR imaging findings of pancreatic abnormalities in patients with primary sclerosing cholangitis. MATERIALS AND METHODS: MR images in 24 patients with primary sclerosing cholangitis were retrospectively reviewed for evidence of pancreatic abnormalities, including abnormalities of signal intensity; changes in size and morphology; abnormalities of pancreatic ducts; presence of focal lesions, pseudocysts, and peripancreatic edema or fluid; and contrast-enhancement pattern if dynamic studies were available. RESULTS: Eleven patients with pancreatic abnormalities on MR images (case patients) and 13 patients with normal MR findings of the pancreas (cohort patients) were identified. The most common finding in case patients was increased signal intensity of the pancreas on T2-weighted images (73%), followed by decreased signal intensity on T1-weighted images (55%) and decreased enhancement on arterial-phase contrast-enhanced images (50%). Other findings included marked enlargement of the pancreas (27%), narrowing of pancreatic ducts (27%), and peripancreatic edema or fluid (27%). The mean value of the anteroposterior diameter of the pancreatic head in the case patients was significantly greater than that in the cohort patients (p = .039). The mean signal-intensity ratio on the T2-weighted images was significantly higher in the case patients than in the cohort patients (p = .007). CONCLUSION: Increased signal on T2-weighted images, decreased signal on T1-weighted images, enlargement of the pancreas, and decreased contrast-enhancement were MR findings of pancreatic disease associated with primary sclerosing cholangitis.     

Sensitivity of an eight-element phased array coil in 3 Tesla MR imaging: a basic analysis.

PURPOSE: To evaluate the performance advantages of an 8-element phased array head coil (8 ch coil) over a conventional quadrature-type birdcage head coil (QD coil) with regard to the signal-to-noise ratio (SNR) and image uniformity in 3 Tesla magnetic resonance (MR) imaging. MATERIALS AND METHODS: We scanned a phantom filled with silicon oil using an 8 ch coil and a QD coil in a 3T MR imaging system and compared the SNR and image uniformity obtained from T(1)-weighted spin echo (SE) images and T(2)-weighted fast SE images between the 2 coils. We also visually evaluated images from 4 healthy volunteers. RESULTS: The SNR with the 8 ch coil was approximately twice that with the QD coil in the region of interest (ROI), which was set as 75% of the area in the center of the phantom images. With regard to the spatial variation of sensitivity, the SNR with the 8 ch coil was lower at the center of the images than at the periphery, whereas the SNR with the QD coil exhibited an inverse pattern. At the center of the images with the 8 ch coil, the SNR was somewhat lower, and that distribution was relatively flat compared to that in the periphery. Image uniformity varied less with the 8 ch coil than with the QD coil on both imaging sequences. CONCLUSION: The 8 ch phased array coil was useful for obtaining high quality 3T images because of its higher SNR and improved image uniformity than those obtained with conventional quadrature-type birdcage head coil.     

MR imaging of rotator cuff tears]

A total of 115 patients with clinical symptoms and signs suggesting rotator cuff tears underwent MR imaging with a 1.5-Tesla system. The body coil was used as the receiver coil in 24 patients and a single 10 cm surface coil in 91. Arthrography or MR imaging with intra-articular Gd-DTPA (MR arthrography) was performed in 95 of the 115. T2-weighted images with the body coil showed high signal intensity lesions in rotator cuffs in only seven of the 10 patients who had tears demonstrated by arthrography or MR arthrography. On the other hand, T2-weighted images with the surface coil demonstrated high signal intensity lesions in cuffs in all 27 patients who were diagnosed to have tears by arthrography or MR arthrography. In 12 patients, T2-weighted images with the surface coil showed high signal intensity lesions in cuffs, while arthrography and MR arthrography did not show tears. Surgery was performed in four of the 12 patients and partial tears were confirmed. A single 10 cm surface coil, 3 mm slice thickness and 2.5 second repetition time seem to account for the fine visualization of cuff tears by the T2-weighted images. These results suggest that T2-weighted images obtained with the surface coil are superior to arthrography and MR arthrography.     

Carcinoma of the urinary bladder: MR imaging with a double surface coil

Twenty-four patients with carcinoma of the urinary bladder were examined with MR imaging by using both a conventional body coil and a newly designed wraparound double surface coil. All patients had T1- and two patients had T2-weighted pulse sequences with both coils. Because of the long examination times, T2-weighted sequences in all other patients were obtained by using the double surface coil only. Nine patients underwent radical cystectomy, while the other patients had deep transurethral tumor resection and a clinical follow-up of at least 1.5 years. The results of imaging with the surface coil showed a twofold improvement of spatial resolution compared with the images obtained with the body coil. The RF field homogeneity was excellent, and the field of view was sufficiently large to achieve a complete study of the pelvis and the lower abdomen in one sequence. For the T1-weighted images, the higher spatial resolution of the double surface coil resulted in a significant (p less than .10) improvement in tumor staging. The accuracies of double-surface-coil and body-coil imaging were 79% and 54%, respectively. Double-surface-coil imaging appears to provide better MR images of the urinary bladder than body-coil imaging does, resulting in more accurate staging of tumors on T1-weighted pulse sequences.     

Pancreatic adenocarcinoma: detection and staging with dynamic MR imaging

OBJECTIVE: To compare the efficacy of dynamic contrast-enhanced MR imaging and spin-echo T1-weighted with and without fat-saturated MR imaging in the detection and staging of pancreatic adenocarcinoma. METHODS AND MATERIAL: Spin-echo T1-weighted, fat-saturated T1-weighted and dynamic breath-hold 2D-FLASH MR imaging were performed in 25 patients with pancreatic adenocarcinoma. MR images were analysed by calculating the CNR between tumor and normal portion of the pancreas. The CNRs calculated at each sequences were compared. A total of 16 out of 25 patients underwent surgery. Preoperative staging according to TNM classification was also done in patients undergoing surgery. RESULTS: The CNR was significantly different (P<0.05) in the arterial phase of dynamic MR images. The accuracy of 'T' staging was 75% for SE T1-W, fat-saturated T1-W and arterial phase of dynamic MR images. CONCLUSION: The CNRs between pancreatic carcinoma and normal pancreas is significantly higher in dynamic MR sequences than the SE T1-W, fat-saturated T1-W sequences. However, the accuracy of tumor staging according to TNM is equivocal to SE T1-W and fat-saturated T1-W images.     

胰腺MRI:技术及诊断研究

目的 :探讨MR不同序列在胰腺病变诊断中的应用价值。方法 :84例胰腺检查包括 5 0例正常胰腺及 3 4例临床怀疑有病变的胰腺 ,其中包括 15例胰腺癌 ,2例胰岛细胞瘤 ,1例粘液性囊腺瘤 ,4例胰周肿瘤 ,12例胰腺炎。MR扫描序列包括常规SET1WI ;FSET2 WI ;增强前、后的脂肪抑制T1WI和GRE。结果 :3 4例异常胰腺中的 2 7例 ,增强前、后T1WI脂肪抑制像提供了最好的诊断信息 ,其次为增强后立即扫描的GRE像。未增强的GRE像极好地显示了急性胰腺炎的特征 ,SET2 WI像对胰岛细胞瘤及胰腺癌的肝转移显示较为敏感。结论 :增强前、后T1WI脂肪抑制序列及动态增强的GER序列 ,应为胰腺MRI的标准序列。     

OMR, a positive bowel contrast agent for abdominal and pelvic MR imaging: safety and imaging characteristics.

To determine the safety and imaging characteristics of OMR--an effervescent solution of ferric ammonium citrate--as a bowel contrast agent, magnetic resonance (MR) imaging at 1.5 T was performed in 29 volunteers. T1- and T2-weighted images of the upper abdomen and pelvis were obtained before and after oral administration of OMR at doses of 100-400 mg of iron in 300-600 mL of water. Respiratory-ordered phase encoding and presaturation pulses were used routinely for artifact suppression. All dose levels of OMR provided marking of the bowel by increasing intraluminal signal intensity; however, the degree and percentage of small bowel opacification appeared more prominent at higher dose levels of iron. Semisolid or watery bowel movements were noted in 31% of subjects, but no clinically important laboratory abnormalities were seen. OMR improved delineation of the head of the pancreas on T1-weighted images in 72% of subjects but was less useful in defining the body and tail. OMR is a safe and effective bowel contrast agent for MR imaging. Because artifacts due to movement of hyperintense bowel may degrade the images, OMR may be most useful on short TR/TE or fast imaging pulse sequences or when combined with antiperistaltic agents.     

MR imaging features of solid-pseudopapillary tumor of the pancreas.

Solid-pseudopapillary tumor (SPT) of the pancreas is characterized as cystic, necrotic, and hemorrhagic degeneration. In this study, magnetic resonance (MR) findings of 4 cases were reviewed. Patchy or spotty areas of high intensity that suggested hemorrhagic degeneration were constantly detected on fat-suppressed T(1)-weighted images. Dynamic contrast-enhanced MR imaging revealed mild and gradual increase of contrast enhancement in solid portions. Multi-contrast MR imaging that included fat-suppressed T(1)-weighted imaging and dynamic contrast-enhanced imaging allowed accurate diagnosis of SPT and its differentiation from other tumors.     

Abdominal Magnetic Resonance Imaging at 3.0 T: What Is the Ultimate Gain in Signal-to-Noise Ratio?

RATIONALE AND OBJECTIVES: The purpose of this study was to calculate the gain in signal-to-noise ratio (SNR) of four human abdominal tissues at 3.0 Tesla (T) compared with standard 1.5 T and to validate this calculation in vivo. MATERIALS AND METHODS: The expected gain in SNR at 3.0 T in the liver, pancreas, spleen, and kidney compared with standard 1.5 T was approximated theoretically for a T2-weighted HASTE (half-Fourier acquisition single-shot turbo spin-echo) and a T1-weighted gradient-echo in- and opposed-phase sequence. Fifteen healthy male subjects underwent abdominal MR imaging using a 1.5 T and 3.0 T scanner. Coronal T2-weighted HASTE images and axial T1-weighted gradient-echo in- and opposed-phase images were acquired using the sequence parameters optimized by the vendor. RESULTS: Except for opposed-phased imaging of pancreatic tissue, in vivo adjusted SNR values of all abdominal tissues were significantly higher at 3.0 T for all sequences (P < .05). The highest overall gain in SNR was achieved with the HASTE sequence ranging from 3.8-fold for renal imaging to 7.4-fold for hepatic imaging. The theoretical calculation of SNR gain was in good agreement with the experimentally measured gain in SNR for the HASTE and the in-phase sequence. CONCLUSION: High-field abdominal MR imaging at 3.0 T offers significantly higher SNR compared with standard 1.5 T MR imaging.     

MR imaging of pancreatic changes in patients with transfusion-dependent beta-thalassemia major.

OBJECTIVE: The aim of this study was to evaluate MR imaging changes of the pancreas in patients with transfusion-dependent beta-thalassemia major. SUBJECTS AND METHODS: Twenty patients with transfusion-dependent beta-thalassemia major were examined using MR imaging at 0.5 T, with spin-echo T1-weighted, fast spin-echo T2-weighted, and gradient-echo T2*-weighted sequences. Image analysis was performed to assess pancreas-to-fat signal intensity ratios for all pulse sequences. Pancreatic exocrine and endocrine function and serum ferritin levels were assessed. Twenty healthy volunteers underwent MR imaging with the same three sequences and served as a control group. RESULTS: The pancreas-to-fat signal intensity ratio was significantly decreased in 17 (85%) of the 20 patients on spin-echo T1-weighted images (p < .05), fast spin-echo T2-weighted images (p < .01), and gradient-echo T2*-weighted images (p < .01) when compared with the 20 volunteers in the control group. The pancreas-to-fat signal intensity ratio was significantly increased in three (15%) of the 20 patients on spin-echo T1-weighted images (p < .01) and fast spin-echo T2-weighted images (p < .05). In addition, in the 20 patients, we found a significant correlation between increased pancreas-to-fat signal intensity ratios and decreased serum trypsin levels (r = -.77, p < .01 for spin-echo T1-weighted sequences; r = -.75, p < .05 for fast spin-echo T2-weighted sequences; and r = -.74, p < .05 for gradient-echo T2*-weighted sequences). Likewise, for the 20 patients, we found a significant correlation between decreased pancreas-to-fat signal intensity ratios and increased serum ferritin levels for gradient-echo T2*-weighted images (r = -.65, p < .01). No correlation was found for the other clinical parameters evaluated. CONCLUSION: MR imaging revealed signal intensity changes in the pancreas of patients with transfusion-dependent beta-thalassemia major. Patients with a major impairment of the exocrine pancreatic function had higher signal intensity of the pancreas because of fatty replacement of the parenchyma.     

Imaging of pancreatic neoplasms: comparison of MR and CT

Thirty-two patients with pathologically proved pancreatic carcinomas or cystadenomas were evaluated with MR images obtained with T1-weighted spin echo (short TR/short TE), inversion recovery, and T2-weighted spin-echo (long TR/long TE) pulse sequences. CT was used as the reference standard to determine the ability of MR to delineate normal and abnormal pancreatic anatomy and thereby to exclude or detect pancreatic malignancy. Short TR/short TE spin-echo sequences were significantly better (p less than .05) than inversion recovery or T2-weighted spin-echo sequences in resolution of both normal and abnormal anatomy. Resolution of pancreatic anatomy correlated (r = .9) with the image signal-to-noise ratio. In seven (22%) of 32 cases, MR visualized pancreatic tumors better than CT did because it showed a signal intensity difference between the tumor and normal pancreatic tissue. Overall, the slight superiority of MR over CT for tumor visualization tended to occur in larger tumors and was not statistically significant. On T1-weighted images, 63% (20 of 32) of pancreatic tumors studied had lower signal intensities than normal pancreatic tissue, whereas on T2-weighted sequences (TE = 60, 120, and 180 msec) only 41% (13 of 32) of tumors had increased signal intensities. Currently available MR imaging techniques offer no significant advantages over CT for evaluating the pancreas for neoplasia.     

Surface coil MR imaging of abdominal viscera. Part I. Theory, technique, and initial results

Prototype surface coil magnetic resonance (MR) images were obtained from phantoms and 42 subjects at 0.6 T to assess the feasibility of imaging relatively deep abdominal structures. Surface coil images demonstrated a two- to fourfold improvement in signal-to-noise ratio (SNR) when compared with whole-body coil images with the same resolution elements. This improvement in SNR allowed us to obtain images with thinner sections, higher in-plane resolution, or, alternatively, a decrease in image time. Compared with body images, surface coil images demonstrated greater anatomic detail and reduction in motion artifacts. Despite the limited field of view in very large patients, the use of surface coils improves the diagnostic capability of MR imaging of the abdomen.     

High-resolution MRI of pancreatic masses with a new circularly polarized body phased-array coil

A total of 18 patients with clinical suspicion of a pancreatic tumor underwent dynamic contrast-enhanced CT and MRI examinations. A fat-suppressed T1-weighted 2D fast-low-angle-shot (FLASH) sequence and a T2-weighted spin-echo (SE) sequence were applied in a transverse orientation using a circularly polarized (CP) body phased-array coil. The FLASH sequence was repeated after Gd-DTPA administration. The highest spatial resolution was 1.37×1.37×3.00 mm³. In two cases a half Fourier single-shot turbo-SE sequence (HASTE) was additionally applied. In a comparison between CT and MRI, pancreatic masses could be demonstrated and characterized with excellent image quality. The fat-saturated 2D FLASH sequence yielded the highest contrast-to-noise ratios after Gd-DTPA administration between pancreas and inflammatory or neoplastic lesion. One non-contour deforming carcinoma could be detected only with MRI and was only retrospectively visible on CT with an element of uncertainty. Magnetic resonance imaging using a CP body phased-array coil and fat-suppressed T1- and T2-weighted FLASH, SE, and turbo-SE sequences offers diagnostic possibilities in improved imaging of the pancreas.     

3.0 T MRI不同脉冲序列对胰腺疾病的诊断价值

目的 探讨MRI检查不同脉冲序列对胰腺病变的诊断价值。方法 对87例临床怀疑胰腺病变的病人应用3.0 T MR设备进行检查,扫描序列包括双回波T1WI（同相位与反相位成像）、脂肪抑制T1WI（T1WI+FS）、脂肪抑制T2WI (T2WI+FS)、磁共振胆胰管水成像（MRCP）、快速多层面扰相梯度回波(FSPGR)动态增强扫描。由2名放射科医师分析不同脉冲序列的MRI所见。结果 正常胰腺15例,急性胰腺炎27例,慢性胰腺炎30例,胰腺癌15例。T1WI+FS显示胰腺形态与信号最佳,正常胰腺呈稍高信号。在双回波T1WI上,胰腺与周围组织对比度降低。胰腺病变在T1WI上表现为低信号50例,T2WI+FS显示胰周渗出性病变34例。MRCP显示胰管扩张35例,胆管扩张20例,双管征9例。快速扰相梯度回波（FSPGR）动态增强显示胰腺癌13例,肿块在动脉期表现为相对低信号,延迟期轻度强化,周围血管受侵2例。结论 合理应用MR扫描序列有助于提高胰腺病变的诊断效能。     

High-resolution MR imaging of the elbow using a microscopy surface coil and a clinical 1.5 T MR machine: preliminary results

Objective To obtain high-resolution MR images of the elbow using a microscopy surface coil with a 1.5 T clinical machine and to evaluate the feasibility of its use for elbow injuries.Design and patients Five asymptomatic normal volunteers and 13 patients with elbow pain were prospectively studied with MR imaging using a microscopy surface coil 47 mm in diameter. High-resolution MR images using a microscopy coil were obtained with fast spin echo (FSE) proton density-weighted sequence, gradient recalled echo (GRE) T2*-weighted sequence, and short tau inversion recovery (STIR) sequence, with a 1–2 mm slice thickness, a 50–70 mm field of view, an imaging matrix of 140–224×512 using zero fill interpolation, and 2–6 excitations.Results High-resolution MR images of normal volunteers using a microscopy coil clearly showed each structure of the medial and lateral collateral ligaments on GRE T2*-weighted images and FSE proton-density weighted images. Partial medial collateral ligament injury, a small avulsion of the medial epicondyle, and osteochondritis dissecans were well demonstrated on high-resolution MR images.Conclusion High-resolution MR imaging of the elbow using a microscopy surface coil with a 1.5 T clinical machine is a promising method for accurately characterizing the normal anatomy of the elbow and depicting its lesions in detail.     

MR imaging in the diagnosis of pancreatic disease

MR imaging examinations of 20 patients with normal pancreas and of 38 patients with suspected pancreatic disease were analyzed retrospectively to evaluate the ability of MR imaging to depict the normal and abnormal pancreas, establish MR criteria for various pancreatic diseases, determine if MR imaging can distinguish among various pancreatic diseases, and compare the usefulness of MR imaging with CT. In all 20 patients with normal pancreas and in 34 of the 38 patients with suspected pancreatic disease excellent or good evaluation of the pancreas was achieved. A 0.35-T magnet (Diasonics MT/S) was used, and both T1- and T2-weighted images were needed. T1 and T2 relaxation times and MR signal intensities showed no specific pattern to allow consistent differentiation between normal and diseased pancreatic tissue or to distinguish between tumor and inflammation. In the 29 patients in whom MR and CT images could be compared, MR imaging and CT provided equivalent information in 20 (69%). In 4 patients (14%), MR imaging added information, and in 5 patients (17%) of cases, MR imaging yielded less information than CT. MR imaging of the pancreas was found to be superior to CT in selected instances, such as in the staging of pancreatic neoplasms (n = 4) and in the evaluation of pancreatic disease after surgery (n = 3). We conclude that, at present, MR imaging should not be used as the screening method for pancreatic disease but should be reserved as an adjunct when the information provided by CT is insufficient.     

Imaging features of pancreatoblastoma: a case report

We present a patient with pancreatoblastoma along with a discussion of various cross-sectional imaging features. The tumor was a large multilocular cystic mass with solid components in the left retroperitoneal space. There were fine internal echoes on ultrasonography, and the signal intensity was high on both T1- and T2-weighted MR images in most of the locules, suggesting the presence of hemorrhagic debris. Among the various retroperitoneal organs displaced by the tumor, only the pancreatic tail was inseparable from the mass, suggesting that the pancreatic tail was the origin of the tumor. Pancreatoblastoma should be included in the differential diagnosis when a large left upper quadrant mass with these imaging features is seen in infants and young children.     

Hepatobiliary and pancreatic manifestations of cystic fibrosis: MR imaging appearances.

Magnetic resonance (MR) imaging and MR cholangiopancreatography are useful, noninvasive techniques for the assessment of pancreatic and hepatobiliary complications in cystic fibrosis. Abnormalities of the pancreas in cystic fibrosis are typically characterized by fat deposition, which has increased signal intensity on T1-weighted MR images, and pancreatic fibrosis, which has low signal intensity on both T1- and T2-weighted images. Pancreatic cysts are a relatively common finding; these cysts are typically quite small but are well demonstrated at MR imaging and MR cholangiopancreatography. Pancreatic duct abnormalities are also occasionally seen. Hepatic manifestations range from hepatomegaly and diffuse fatty infiltration to severe cirrhosis with fibrotic change, regenerative nodules, and portal hypertension. Splenomegaly is often characterized by siderotic nodules that manifest as multiple focal areas of abnormal low signal intensity within the spleen. Biliary manifestations include cholelithiasis, stricturization, and narrowing or dilatation of intra- and extrahepatic bile ducts. Gallbladder abnormalities including microgallbladder are also readily demonstrated. MR cholangiopancreatography can be used to help determine the presence and severity of biliary complications without resorting to more invasive procedures and, in conjunction with MR imaging, may prove useful in the assessment of patients with cystic fibrosis who present with abdominal symptoms that suggest hepatobiliary involvement.     

Evaluation of the pancreas by MRI

Using T1-, P- and T2-weighted images of the upper abdomen obtained on 1.5 T MRI system, 18 items on the pancreas were evaluated in 89 controls. The items included pancreas sizes on T1-weighted image. pancreatic intensity compared with those of renal cortex, subcutaneous fat tissue, liver and spleen, obliteration of pancreas margin, and diameter of pancreatic duct on all images. Normal criteria, which were determined from data in the controls, were applied to images in the 40 patients with pancreatic or peripancreaticdiseases. All 4 patients with an extra-pancrcatic tumor had no abnormality of pancreatic intensity. pancreatic margin, and pancreatic duct on T2-weighted image, except for pancreatic sizes and intensities at tumor sites. In contrast. 34 of 36 patients with pancreatic disease had abnormalities which pathologically depended on acute and/or chronic pancreatitis.