胰腺疾病的MRI诊断

随着MBI成像技术的迅速发展和MBI的广泛应用，利用MBI诊断胰腺疾病正引起人们的普遍关注。现代MRI技术包括屏气T1加权成像及其脂肪抑制、T2加权成像及其脂肪抑制、MBI动态增强扫描、MR胰胆管成像和MR血管成像。这些脉冲序列各自有不同的组织对比机制，而且是互相补充的，它们的综合应用，可以较全面地评价胰腺及胰腺病变，从而明显改善了MBI对胰腺疾病的检测和诊断。本文着重介绍胰腺的MR成像技术，正常解剖、先天性异常和常见疾病的NR诊断价值。     

MR imaging for blunt pancreatic injury

Objective

To study the MR imaging features of blunt pancreatic injury.

Materials and methods

Nine patients with pancreatic injury related to blunt abdominal trauma confirmed by surgery performed MR imaging. Two abdominal radiologists conducted a review of the MR images to assess pancreatic parenchymal and pancreatic duct injury, and associated complications.

Result

Diagnostic quality MR images were obtained in each of the nine patients. In the nine patients, pancreatic fracture, laceration and contusion were depicted on MR imaging in five, one and three patients, respectively. There were six patients with pancreatic duct disruption, eight patients with peripancreatic fluid collections, and four patients with peripancreatic pseudocyst or hematoma, respectively. All of the MR imaging findings was corresponded to surgical findings.

Conclusion

MR imaging is an effective method to detect blunt pancreatic injury and may provide information to guide management decisions.     

MR扩散加权成像在胰腺癌中的应用

胰腺癌是腹部最常见的恶性肿瘤,5年生存率不超过5%[1]或只有0.4%~2%.据报道,胰腺癌患者在过去30年几乎没有提高生存率[2].早期胰腺癌一般局限于实质内,直径<2 cm,无胰腺外浸润及淋巴结转移,其临床表现隐匿不易发现,有80%~90%的患者因为发现太迟以至于失去手术机会[3].所以对提高胰腺癌患者的生存率来说,快速准确的诊断显得尤为重要.     

Mangafodipir trisodium-enhanced MR imaging of pancreatic disease

Our study aimed to assess the diagnostic capabilities of mangafodipir trisodium-enhanced MRI for the evaluation of pancreatic disease. Sixty-three patients suspected of having pancreatic disease underwent MRI with a 1.5-T device. After the acquisition of axial and coronal T2-weighted sequences, the MR protocol included T1-weighted fat-suppressed breath-hold SPGR images obtained before and 30 min after the infusion of Mn-DPDP (Teslascan). The detection of a focal pancreatic lesion and its intensity were evaluated in consensus by two observers, who also attempted to characterize each lesion as benign or malignant. The reviewers were blinded to patient identification and all clinical, laboratory and previous imaging findings. MR imaging results were correlated with surgery (n=37), laparoscopy (n=1), biopsy (n=2) and imaging follow–up (n=22). Sixty-two subjects were effectively included in our analysis because one patient was lost to follow-up; final malignant and benign diagnoses were determined in 22 (35%) and 29 (47%) of the patients, respectively. The level of confidence in the diagnosis of the pancreatic lesion was significantly increased by the administration of Mn-DPDP as demonstrated by ROC analysis of unenhanced and post-contrast image sets (P=0.009). Overall, on the basis of observers’ readings, MR assessment of pancreatic disease resulted in 57 correct diagnoses (accuracy, 92%) and five (8%) incorrect diagnoses. The sensitivity, specificity, positive predictive value and negative predictive value of the reviewers for the detection of pancreatic lesions and for the differentiation between benign and malignant masses were 91% (95% CI: 84 and 98%), 93% (95% CI: 86 and 99%), 87% (95% CI: 79 and 95%) and 95% (95% CI: 89 and 100%), respectively. Mn-DPDP-enhanced MRI is an effective diagnostic tool for evaluating pancreatic disease.     

MR cholangiopancreatography: evaluation of common pancreatic diseases

In the evaluation of common pancreatic diseases, MRCP is a noninvasive alternative to ERCP. Ductal anatomy can be ascertained without risk of complications. MRCP is valuable in defining common anatomic variants, determining the state of the pancreatic duct in pancreatitis, and characterizing neoplasms, especially combined with other MR imaging sequences. With the advent of MRCP, techniques requiring endoscopy and percutaneous access are largely reserved for histologic diagnosis and treatment, or for cases in which MRCP fails to establish a diagnosis.     

Endoluminal MR imaging of anorectal diseases.

Endoluminal magnetic resonance imaging (MRI) has become an important technique in the diagnostic work-up of patients with anorectal diseases. The high spatial resolution of endoluminal MRI gives a detailed demonstration of the anal and rectal anatomy and pathology. This technique has been demonstrated to be superior to endoluminal sonography and body coil MRI. Endoanal MRI and phased-array coil MRI seem to have comparable results in perianal fistulas, but comparative data are lacking. Phased-array coil MRI is the imaging technique of choice for imaging rectal tumors, while endoluminal MRI is the alternative technique for imaging rectal tumors and the preferred technique for imaging anal tumors. Endoluminal MRI is superior to phased-array coil MRI in fecal incontinence, as phased-array coil MRI does not give the detailed spatial resolution required for evaluation of anal sphincter lesions.     

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.     

Current status of imaging in pancreatic diseases

Recent technological developments in multidetector CT allow pancreatic imaging in a single breath-hold, which is especially valuable in obtaining isotropic three-dimensional reformations that improve our ability to provide accurate preoperative vascular mapping. Advanced MR technology allows faster imaging of pancreas, thus facilitating MR cholangiopancreatography. Use of tissue-specific MR contrast agents, endoscopic ultrasound, and positron emission tomography (PET) in pancreatic imaging has evolved considerably. This review article discusses the roles of CT, MR, endoscopic ultrasound, and PET imaging in the pancreas.     

Comprehensive MR imaging of acute gynecologic diseases.

Rapid advances in techniques of magnetic resonance (MR) imaging have enabled diagnosis of acute gynecologic conditions, which are characterized by sudden onset of lower abdominal pain, fever, genital bleeding, intraperitoneal bleeding, or symptoms of shock. The chemical-selective fat-suppression technique not only helps establish the characteristics of lesions that contain fat components but also increases the conspicuity of inflammatory lesions. When a T2-weighted image is obtained with a very long effective echo time (>250 msec), even a small amount of ascites can be easily identified and the contrast between urine and complex fluid becomes more conspicuous. T2*-weighted images are useful for identification of hemorrhagic lesions by demonstrating deoxyhemoglobin and hemosiderin. Contrast material-enhanced dynamic subtraction MR imaging performed with a three-dimensional fast field-echo sequence and a rapid bolus injection of gadopentetate dimeglumine allows evaluation of lesion vascularity and the anatomic relationship between pelvic vessels and a lesion and allows identification of the bleeding point by demonstrating extravasation of contrast material. To optimize the MR imaging examination, attention should be given to the parameters of each pulse sequence and proper combination of the sequences.     

乳腺乳头病变的MRI特点

【摘要】目的：回顾性分析良恶性乳头病变的乳腺MRI特点,以提高诊断正确率。方法：搜集2012年9月-2015年9月本院经手术病理证实且术前行MRI检查的13例乳头病变患者的病例资料,分析病灶的形态学特征及强化特点。所有病例MRI表现由2名从事乳腺影像诊断的放射科医师共同阅片,讨论达成一致诊断意见。结果：13例患者的病理结果分别为：软纤维瘤2例,乳头腺瘤2例,乳腺炎性病变累及乳头3例,乳头派杰病（PD）6例。在MRI上,2例乳头软纤维瘤均表现为乳头上小结节,轻度强化。2例乳头腺瘤MRI表现为乳头增大伴乳头内强化结节。3例乳头炎性病变中,1例MRI上表现为乳头内环形强化结节,乳腺内未见异常强化;另外2例MRI上表现为乳头轻度或明显异常强化,乳腺内可见异常强化炎性灶。6例乳头PD中,乳腺内均有异常强化恶性病灶;其中5例MRI上表现为患侧乳头明显不均匀强化,另1例患侧乳头未见异常强化。结论：乳腺乳头病变在MRI上多发表现为乳头内强化结节或乳头不均匀强化,结合乳头病变强化特点及乳腺内有无可疑恶性病灶,有助于鉴别诊断。     

Diffusion weighted MR imaging of pancreatic islet cell tumors

Purpose

The aim of our study is to demonstrate the feasibility of body diffusion weighted (DW) MR imaging in the evaluation of pancreatic islet cell tumors (ICTs) and to define apparent diffusion coefficient (ADC) values for these tumors.

Materials and methods

12 normal volunteers and 12 patients with histopathologically proven pancreatic ICT by surgery were included in the study. DW MR images were obtained by a body-phased array coil using a multisection single-shot echo planar sequence on the axial plane without breath holding. In addition, the routine abdominal imaging protocol for pancreas was applied in the patient group. We measured the ADC value within the normal pancreas in control group, pancreatic ICT, and surrounding pancreas parenchyma. Mann-Whitney U-test has been used to compare ADC values between tumoral tissues and normal pancreatic tissues of the volunteers. Wilcoxon Signed Ranks Test was preferred to compare ADC values between tumoral tissues and surrounding pancreatic parenchyma of the patients.

Results

In 11 patients out of 12, conventional MR sequences were able to demonstrate ICTs succesfully. In 1 patient an indistinct suspicious lesion was noted at the pancreatic tail. DW sequence was able to demonstrate the lesions in all of the 12 patients. On the DW images, all ICTs demonstrated high signal intensity relative to the surrounding pancreatic parenchyma. The mean and standard deviations of the ADC values (×10⁻³ mm²/s) were as follows: ICT (n = 12), 1.51 ± 0.35 (0.91-2.11), surrounding parenchyma (n = 11) 0.76 ± 0.15 (0.51-1.01) and normal pancreas in normal volunteers (n = 12), 0.80 ± 0.06 (0.72-0.90). ADC values of the ICT were significantly higher compared with those of surrounding parenchyma (p < 0.01) and normal pancreas (p < 0.001).

Conclusion

DW MR imaging does not appear to provide significant contribution to routine MR imaging protocol in the evaluation of pancreatic islet cell tumors. But it can be added to MR imaging protocol to detect the lesion in a limited number of patients with clinical suspicion for pancreatic ICT with negative or suspicious imaging findings.     

胰腺疾病中胰管异常表现及其影像学诊断进展

胰管异常是胰胆管疾病的重要征象,可见于胰腺各种病变;目前胰管异常影像学检查有ERCP、MRCP、MSCT（MDCT）及EUS等均能较好显示胰管形态特征及病变。本文对正常胰管及各种胰腺疾病中胰管异常的影像学表现加以总结。以增进对胰腺疾病的了解。     

Prospective evaluation of pancreatic tumors: accuracy of MR imaging with MR cholangiopancreatography and MR angiography

PURPOSE: To prospectively assess accuracy of magnetic resonance (MR) imaging, MR cholangiopancreatography (MRCP), and MR angiography in patients suspected of having pancreatic tumors. MATERIALS AND METHODS: Sixty-six patients suspected of having pancreatic tumors underwent MR imaging (unenhanced and contrast material-enhanced MR, MRCP, and contrast-enhanced MR angiography). Two blinded readers prospectively analyzed the images by consensus, and results were correlated with surgery, biopsy, or follow-up findings. Results were tabulated in two-by-two tables. RESULTS: MR assessment of pancreatic lesion status (differentiation of benign vs malignant) resulted in 60 correct diagnoses (accuracy, 91%), and six (10%) false diagnoses. Among histologically proved malignant tumors, MR imaging yielded correct diagnoses in 42 of 44 patients (sensitivity, 95%; 95% CI: 85%, 99%), whereas 18 of 22 patients with benign findings were classified correctly. At MR imaging, findings in four patients with chronic pancreatitis were wrongly categorized as malignant tumors (specificity, 82%; 95% CI: 60%, 95%), and in one patient, a distal common bile duct carcinoma was not detected. In no patient with pancreatic adenocarcinoma was this tumor misdiagnosed as benign. In patients with malignant tumors who underwent resection, local-regional tumor growth and vascular infiltration were accurately classified in 89% and 94%, respectively. MR imaging depicted histologically proved synchronous hepatic metastases in 82%. The positive and negative predictive values for cancer nonresectability were 90% and 83%, respectively, and the accuracy, sensitivity, and specificity were 85%, 69%, and 95%, respectively. CONCLUSION: Unenhanced and contrast-enhanced MR imaging with MRCP and MR angiography offers potential as a noninvasive tool for assessment of patients suspected of having pancreatic tumors.     

Liver metastases from pancreatic adenocarcinoma: MR imaging characteristics

PURPOSE: To describe the magnetic resonance imaging spectrum of appearances of liver metastases from pancreatic ductal adenocarcinoma. MATERIALS AND METHODS: We retrospectively evaluated the MRI exams performed between July 1996 and August 2001 in all patients who had liver metastases from pancreatic adenocarcinoma and histopathologic diagnosis from either the primary pancreatic tumor, liver metastases, or both. Sixteen patients were included in the study. All MR studies were performed at 1.5 T with a standard protocol including T1- and T2-weighted images and serial post-gadolinium spoiled gradient echo (SGE) images. Location, size, number, signal characteristics on T1- and T2-weighted images, and pattern of enhancement on serial gadolinium-enhanced SGE images were assessed. RESULTS: The diameter of metastases ranged from a few millimetres to 4 cm, and 12 patients (75%) had only lesions of 1.5 cm or less. Capsular-based liver metastases were found in 13 patients (81%) and three patients had only capsular-based lesions with a diameter under 1.5 cm. Hypervascular lesions were found in six patients (38%) and hypovascular lesions in 10 patients (62%). Perilesional enhancement was present in 10 patients (62%), with six patients (38%) having ring perilesional enhancement and eight patients (50%) having wedge-shaped perilesional enhancement. CONCLUSION: On MR imaging, hepatic metastases from pancreatic adenocarcinoma show a range of enhancement patterns. Hypervascular metastases are not rare. Capsular based distribution, small diameter, and perilesional enhancement are common features. This retrospective study describes the MR imaging spectrum of appearances of liver metastases from pancreatic adenocarcinoma in patients with histopathologic confirmation of the diagnosis.     

MR imaging of intradural inflammatory diseases of the spine

Twenty-eight patients with intradural inflammatory disease of the spine were studied in order to characterize the MR imaging findings of infectious and inflammatory conditions. Patients were categorized according to the spinal compartment involved. Among the 12 patients in the intradural extramedullary group, unenhanced scans were either normal or nonspecific while contrast-enhanced scans were helpful in visualizing and localizing the lesion. Nevertheless, contrast-enhanced MR studies were unable to differentiate infection and inflammation from tumor in this compartment. Among 16 patients with intramedullary lesions, four had granulomatous disease and 12 had nongranulomatous disease. The granulomatous lesions resembled tumors and displayed MR characteristics of a focal lesion with large nodular enhancement. The patients with nongranulomatous intramedullary lesions exhibited two subsets of MR findings. In the first subset of nine patients, diffuse cord swelling and high signal were seen on long TR images, combined with either no enhancement or peripheral, diffuse, or speckled enhancement of the spinal cord on contrast-enhanced short TR images. In the second subset of three patients, minimal or no spinal cord swelling was displayed despite the visualization of high signal on long TR scans and nodular enhancement with contrast administration on short TR scans. Both subsets were sufficiently unique that nongranulomatous myelitis could usually be differentiated from spinal cord tumors.     

Localization of pancreatic insulinomas with MR imaging at 0.5 T

OBJECTIVE: To determine the role of MR imaging in the localization of pancreatic insulinomas in patients with clinical and laboratory diagnosis of insulin-producing tumor. MATERIAL AND METHODS: Thirty-one patients presenting with signs and symptoms of pancreatic insulinomas were prospectively included in our study. Twenty-six patients underwent surgery, and pathologic specimens were examined: 5 patients, in whom the initial diagnosis of insulinoma was excluded, were also studied and then followed up. All patients were studied with a high gradient power 0.5 T magnet. Images were evaluated by 2 radiologists blinded to previous investigations, tests and results. RESULTS: MR imaging correctly localized 24 of the 26 insulinomas (2 were false-negative and 1 false-positive) and was correctly negative in the 5 control patients. The interobserver agreement had a kappa value of 0.89. CONCLUSION: MR imaging was accurate in localizing pancreatic insulinomas and as a consequence, patients in our institution are now submitted to surgery directly after the MR examination. Invasive methods are considered only in cases in which, despite clear biochemical results, MR imaging has not demonstrated a pancreatic focal lesion.     

MR磁敏感成像技术在脑部血管性病变中的应用

目的探讨MR磁敏感成像（SWI）技术在脑部血管性病变中的应用价值。方法搜集23例脑血管性病变患者，其中海绵状血管瘤7例，静脉血管畸形4例，小动静脉畸形（AVM）3例，Sturge-Weber综合征1例，静脉窦血栓形成2例及陈旧性脑梗死6例。行T1WI、T2WI、SWI序列及增强T1WI和MR血管成像（MRA）检查，计算病灶与正常对照区的校正相位值（CP），评价SWI与其他序列及MRA在显示血管性病变细节的优越性。结果病灶与正常对照区的CP值分别为-0．112±0．032及-0．013±0．004，差异有统计学意义（t=2．167，P〈0．05）。7例海绵状血管瘤，SWI能鉴别出血与血管瘤体，发现更多的小出血灶。4例静脉血管畸形，SWI能发现更多细小的髓静脉向粗大的引流静脉集中。3例小AVM，SWI较MRA更好地显示小供血动脉。1例Sturge-Weber综合征，SWI可清晰显示钙化及脑表面异常的静脉血管网。2例静脉窦血栓形成，SWI可清晰地显示深部引流静脉及脑表面静脉网广泛增粗扩张迂曲，其中1例能发现早期脑出血灶。6例陈旧性脑梗死，SWI可更好地显示病变内陈旧性出血。结论SWI对低流量血管畸形及血管瘤、多发细小出血的显示、静脉窦血栓形成后深部静脉的扩张及早期并发出血以及脑梗死并发出血等具有常规MRI及MRA检查无可比拟的优越性，并能提供病变与正常组织的相位对比改变。