Small bowel neoplastic disease: Demonstration by MRI

This study demonstrates the appearance of small bowel tumors on MR images. Sixteen patients with tumors involving small bowel were studied by MRI. All tumors were proven with histopathology. Eleven patients had primary tumors of the small bowel, which included the following: four carcinoid tumors, three adenocarcinomas, two lymphomas, one leiomyosarcoma, and one leiomyoma. Five patients had recurrent or metastatic disease to small bowel: two patients had colon cancer, one patient had pancreatic cancer, one patient had uterine leiomyosarcoma, and one patient had chloroma (leukemia). MR examination included breath-hold T1-weighted spoiled gradient echo (all patients), immediate postgadolinium-spoiled gradient echo (10 patients), and 2 to 4 minutes postgadolinium T1-weighted, fat-suppressed images (all patients). Tumor size, local extent, signal intensity, and enhancement features of tumor and adjacent tissue were determined. Tumor ranged in diameter from 1 to 9 cm (mean, 4.0 cm). Tumors had similar signal intensity to normal small bowel on precontrast images. Fourteen malignant tumors showed heterogeneous enhancement greater than adjacent bowel on gadolinium-enhanced images. Tumor local extent was best shown on precontrast-spoiled gradient-echo images and postgadolinium T1-weighted fat-suppressed images. Image quality was most consistent on breath-hold images. The results of this study show that small bowel tumors are demonstrable on MR images. Precontrast breath-hold T1-weighted spoiled gradient-echo images and gadolinium-enhanced fat suppressed images demonstrate tumor extent most reliably.     

Malignant lesions of the liver with high signal intensity on T1-Weighted MR images

Our purpose was to identify the histologic types of malignant liver lesions with high signal intensity (SI) on T1-weighted images and to describe the MR imaging features. Thirteen patients with malignant liver lesions high in SI on T1-weighted images were studied with a 1.5-T MR imager using pre- and serial postcontrast spoiled gradient-echo (SGE) sequences (all patients), T2-weighted fat-suppressed spin-echo sequences (all patients), precontrast T1-weighted fat-suppressed spin-echo sequences (five studies in five patients), and precontrast out-of-phase SGE sequences (seven studies in six patients). Images were reviewed retrospectively to determine number of lesions; lesion size; SI of lesions on T1-weighted, T2-weighted, and fat-attenuated T1-weighted images; distribution of high SI in lesions on T1-weighted images; and tumor enhancement pattern. Seven patients had multiple tumors high in SI on T1-weighted images and six patients had solitary tumors. Seventy-two lesions were less than 1.5 cm in diameter and 35 lesions were more than 1.5 cm in diameter. Nine patients had solid malignant lesions and four patients had cystic malignant lesions. All tumors more than 1.5 cm in diameter were heterogeneously high in SI on T1-weighted images, and all tumors less than 1.5 cm were completely homogeneous or homogeneous with a small central hypointense focus. All tumors were more conspicuous on T1-weighted fat-attenuated images, both on excitation spoiled fat-suppressed spin-echo or on out-of-phase SGE images with the exception of one fat-containing hepatocellular carcinoma (HCC). In one patient with melanoma metastases and one patient with multiple myeloma nodules, appreciably more lesions were detected on out-of-phase SGE images. Causes of hyperintensity were considered to be either fat, melanin, central hemorrhage, or high protein content, all of which may be seen in a variety of tumors. Fat-attenuation techniques are helpful in the detection of these lesions.     

MRI of carcinoid tumors: spectrum of appearances in the gastrointestinal tract and liver

The purpose of this study was to evaluate the spectrum of appearances of gastrointestinal carcinoid tumors at magnetic resonance imaging (MRI) and to elucidate patterns of appearances of carcinoid liver metastases on precontrast and postgadolinium images. The MR examinations of 29 patients (11 men, 18 women; age range, 33-87 years) with histologically confirmed gastrointestinal carcinoid tumors, representing our complete 9.5 years of experience with this entity, were retrospectively reviewed. Twelve patients had MR examinations prior to resection or biopsy of the primary tumor (preoperative group); 17 patients were imaged postsurgically (postoperative group). All MR studies were performed at 1.5 T and comprised T1-weighted spoiled gradient echo (SGE), T2-weighted fat-suppressed turbo spin echo, HASTE, and serial postgadolinium T1-weighted SGE sequences without and with fat suppression. Morphology, signal intensity, and contrast enhancement of primary tumors and of metastases to the mesentery, peritoneum, and liver were evaluated. Primary tumors were visualized in 8 of 12 patients and best demonstrated on postgadolinium T1-weighted fat-suppressed images. The appearance of primary tumors was a nodular mass originating from the bowel wall (4 of 12 patients) or regional uniform bowel wall thickening (4 of 12 patients) with moderate intense enhancement on postgadolinium images. In 4 of 12 patients the primary tumor was prospectively not seen. Mesenteric metastases, seen in eight patients, presented as nodular masses and were associated with mesenteric stranding in seven patients. A total of 156 liver metastases were evaluated in 16 patients. On precontrast T1- and T2-weighted images, 117 metastases (75%) were hypointense and hyperintense, respectively. A total of 146 metastases (94%) were hypervascular, showing moderate intense enhancement during the hepatic arterial phase, and 9 metastases (6%) were hypovascular. Twenty-three metastases (15%) were visible only on immediate postgadolinium images. MRI is able to demonstrate findings in carcinoid tumors, including the primary tumor, mesenteric metastases, and liver metastases. Liver metastases are commonly hypervascular and may be demonstrable only on immediate postgadolinium images.     

Solitary fibrous tumor of the pleura: MR appearance and enhancement pattern

PURPOSE: The aim of the current study was to characterize the MR appearance of solitary fibrous tumor of the pleura (SFTP). METHOD: Twenty-two consecutive patients with histologically confirmed SFTP were retrospectively evaluated with MRI. RESULTS: Tumors demonstrated low signal intensity (n = 18, 82%), iso signal intensity (n = 2, 9%), and high signal intensity (n = 2, 9%) on T1-weighted images. On T2-weighted images, tumors were observed as low signal intensity (n = 10, 45%), high signal intensity (n = 2, 9%), and mixed signal intensity (n = 10, 45%). Solid component in the proliferation of tumor cells corresponded to low signal intensity in 12 tumors (55%) on T2-weighted images. On gadolinium-enhanced T1-weighted images, inhomogeneous enhancement (n = 18, 82%), nodular enhancement (n = 6, 27%), and homogeneous enhancement (n = 4, 18%) were observed. The enhanced lesion within the tumors had dense tumor tissue and dilated microvessels in the pathologic specimen. CONCLUSION: SFTP shows variable appearance and enhancement pattern on MRI according to morphologic tumor heterogeneity.     

Renal cell cancer: Incidence of hemorrhage on MR images in patients with chronic renal insufficiency

This study describes the occurrence of hemorrhage in renal cancer in patients with chronic renal insufficiency as shown on MR images. Thirteen consecutive patients with chronic renal insufficiency who had his tologically proven renal cancer and underwent MRI at 1.5 T were entered in the study. MR examinations included spoiled gradient echo (SGE) and T1-weighted fat-suppressed imaging pre- and postgadolinium administration. All renal cancers were well shown on MR images and were most clearly depicted on postgadolinium T1-weighted fat-suppressed images. Tumors in 12 of 13 patients had regions of high signal intensity on precontrast T1-weighted images. Histology demonstrated intratumoral hemorrhage in all 12 of these patients. Four hemorrhagic tumors were largely cystic on imaging studies. One of these cancers altered in appearance from largely cystic with extensive hemorrhage to largely solid with substantial enhancement after a 2.5-year interval. Renal cancers demonstrated minimal enhancement (11 patients) on early postgadolinium images and were minimally enhanced on delayed images in 10 of 13 tumors. Two renal cancers demonstrated intense enhancement. Renal cancers are well shown on MR images in patients with chronic renal insufficiency. Because of the common occurrence of hemorrhage into renal cancers in patients with renal insufficiency, caution should be exercised when evaluating hemorrhagic cystic lesions in these patients.     

The MRI of extraadrenal pheochromocytoma in the abdominal cavity

The purpose of this study was to summarize the MR appearances of extraadrenal pheochromocytoma in the abdominal cavity and evaluate the capabilities of MRI in diagnosis of the tumor. Eleven consecutive patients with an extraadrenal pheochromocytoma in abdominal cavity who underwent preoperative 0.5 T (n=5) or 1.5 T (n=6) superconductor MRI and had a surgical resection were enrolled in the study. The MR scanning protocol included axial T(2)-weighted imaging with or without fat-suppressed sequences, axial and coronal uncontrast and contrast T(1)-weighted sequences with or without fat suppression. The extraadrenal pheochromocytomas were found in retroperitoneum (n=5), the urinary bladder (n=1), the pelvis (n=1), the right prerenal area (n=1), the renal hilus (n=1), the left paramusculus psoas major (n=1) and liver (n=1). The mean maximal diameter of tumors was 55.9 mm (range 17.8-162.2 mm). The high signal intensity was seen on T(2)-weighted imaging in all tumors compared to muscle or liver, especially with fat suppression. The intratumoral septa and capsules were shown in 63.6% and 72.7% of cases, respectively, which had low signal intensity on T(2)-weighted imaging. These relative characteristics may be helpful for qualitative diagnosis of extraadrenal pheochromocytomas with MRI. Other usefulness of MRI was to locate the position, to decide the range of tumors and to show well the relationship between the tumor and near structures.     

Ampullary carcinoma: Demonstration by current MR techniques

The objective of this study was to demonstrate the appearance of ampullary carcinoma using current MR techniques, including fat suppression, gadolinium enhancement, and MR cholangiography. Nine patients with ampullary carcinoma were examined by MRI at 1.5 T. MR examinations included T1-weighted spoiled gradient echo, T1-weighted fat-suppressed, and immediate postgadolinium spoiled gradient echo images for all patients and MR cholangiography for three patients. The imaging features of ampullary carcinomas, including tumor size and morphology, signal intensity, and enhancement characteristics, were determined. Ampullary carcinomas shown on MR images ranged in size from 1.5 to 5.5 cm. Tumors were low in signal intensity on precontrast T1-weighted spoiled gradient echo and T1-weighted fat-suppressed images relative to normal pancreatic tissue and enhanced less than normal pancreas on immediate postgadolinium spoiled gradient echo images. Tumor conspicuity was greatest on immediate postgadolinium spoiled gradient echo images. MR cholangiography demonstrated high grade obstruction of the common bile duct and mild dilatation of the pancreatic duct at the level of the ampulla with abrupt termination of the ducts in two untreated patients and moderate dilatation of the common bile duct in one patient who had a biliary stent. Ampullary carcinomas can be demonstrated on MR images as small masses arising at the ampulla. Tumors are well defined on immediate postgadolinium spoiled gradient echo images.     

儿童戈谢病骨骼影像特征分析

目的 探讨儿童戈谢病骨骼病变的X线平片及MRI表现特点.方法 109例戈谢病患儿均行常规脊柱正、侧位及双股骨正位X线检查,同时行骨盆止位检查18例,左腕正位检查14例;14例患儿同时行股骨MR平扫.MR扫描序列为标准T1WI、T2WI、T2压脂像冠状面及矢状而扫描.综合分析其影像特点.结果 骨骼异常X线征象包括:长骨干骺端烧瓶样畸形89例(81.7%)、骨质稀疏91例(83.5%)、长骨十骺端密度不同程度的减低86例(78.9%)、骨皮质变薄69例(63.3%)、溶骨性破坏31例(28.4%)、骨硬化12例(11.0%)、骨囊性病变16例(14.7%),病理性骨折26例(23.9%),其中椎体压缩性骨折24处、股骨颈陈旧性骨折5处、脊柱弧形后凸3例、股骨头碎裂变形4例、髋关节脱位4例.,14例股骨MRI显示,T1WI及T2WI骨髓内均可见异常信号,分别表现为T1WI、T2WI信号减低4例;在T2WI及压脂像信号广泛减低的基础上出现限局性高信号或混杂信号10例.结论 儿童戈谢病骨骼病变的影像表现有一定特征性,对临床诊治及观察疗效具有较大的帮助.

Abstract：

Objective To discuss the imaging features of skeletal changes in children with Gaucher disease on X-ray and MRI images.Methods One hundred and nine children with Gaucher disease were enrolled in this study.They all received routine X-ray for spine with anterior-posterior(A-P)and lateral view and bilateral femurs with A-P view.Among them.18 patients received X-ray for pelvic with A-P view.14 patients received X-ray for left wrist with A-P view.and 14 patients received MRI scan for femur.The MRI scan included T1-weighted imaging,T2-weighted imaging and fat-suppressed T2-weighted imaging with short tau inversion recovery(STIR)sequence.The imaging features of the X-ray and MRI images were analyzed retrospectively.Results The most common feature is osteoporosis,which presented in 91 cases (83.5%).Besides this,decreased density of metaphysis occurred in 86 cases(78.9%).erlenmeyer flask deformity of metaphysis occurred in 89 patients(81.7%),thinner cortex occurred in 69 cases(63.3%),osteolytic destruction occurred in 31 cases(28.4%).pathological fractures occurred in 26 cases (23.9%),osteosclerosis occurred in 12 cases(11.0%).cystic degeneration of bone occurred in 16 cases (14.7%),and dislocation of the hip occurred in 4 cases.All 14 patients received MRI presented abnormal signals.Among them,4 patients presented low signal intensity both on T1-weighted and T2-weighted images in bone marrow;the other ten presented high signal intensity mixed in low signal intensity areas on T2-weighted and fat-suppressed T2-weighted images.Conclusions The imaging features of skeletal changes in children with Gaucher disease are of some characteristics,which could provide useful information for the clinical treatment.     

MRI of musculoskeletal extraspinal tuberculosis

PURPOSE: The aim of this study was to describe the MR findings in extraspinal musculoskeletal tuberculosis (EMT). METHOD: A retrospective review was conducted of the MR findings of 18 patients with microbiologically and/or pathologically proven EMT. All MR studies were performed using T1-and T2-weighted spin echo sequences. T1-weighted spin echo sequences after Gd-DTPA injection were obtained for 12 patients. The MR images were evaluated for abnormalities in joints, bones, and soft tissues, and the results were grouped by anatomic localization, frequency distribution of structures affected, and morphologic patterns of involvement. RESULTS: Isolated soft tissue tuberculosis was found in 10 (55.5%) patients and involvement of more than one structure in 8 (44.4%). Pyomyositis (n = 6) and arthritis with involvement of adjacent soft tissues (n = 7) were the most common forms of presentation. One patient presented with isolated fascial superficial tissue involvement in one leg. Isolated pyomyositis involving one (n = 3) or two (n = 3) muscles was homogeneous in six cases and showed intermediate (n = 6), low (n = 2), or high (n = 1) signal intensity on T1-weighted images and a high and very hyperintense signal on T2-weighted images. The tenosynovitis synovial fluid was homogeneous (n = 1) or heterogeneous with multiple tiny hypointense nodules (n = 1) on T2-weighted images. The subdeltoid bursitis fluid was characterized by homogeneous low signal intensity with a hyperintense rim (n = 2) on T1-weighted images and homogeneous (n = 1) or heterogeneous hyperintense signals with areas of low signal intensity (n = 1) on T2-weighted images. In tuberculous arthritis, the synovial joint fluid (n = 7) showed heterogeneous (n = 4) or homogeneous (n = 3) low signal intensity on T1-weighted images and high or very high signal intensity on T2-weighted images. Where involved, the adjacent muscle(s) (n = 8) were usually hypointense on T1-weighted images and very hyperintense on T2-weighted images. Associated cellulitis was found in arthritis with involvement of neighboring soft tissues (n = 5), pyomyositis (n = 2), and tenosynovitis (n = 1). The images obtained after Gd-DTPA showed peripheral (n = 10) or heterogeneous (n = 1) enhancement or no enhancement (n = 1). CONCLUSION: The MR findings for EMT are variable. Although diagnosis is dependent largely on prior presumption and clinical context, MRI provides valuable guidelines in defining the extent of the lesions to select the appropriate treatment and for follow-up of abnormalities.     

Malignant hepatic tumors: Changes on MRI after hepatic arterial chemoembolization – preliminary findings

This study describes the MR appearances of malignant hypervascular liver lesions pre- and post-hepatic-arterial chemoembolization, with correlation to serial imaging and clinical responses. Eight patients with malignant hypervascular liver lesions underwent pretreatment and posttreatment MR examination on a 1.5-T MR imager. MR sequences included T1-weighted spoiled gradient echo (SGE), T2-weighted fat-suppressed spin echo or turbo spin echo, and dynamic gadolinium-enhanced SGE images. All patients underwent pretreatment, initial posttreatment, and subsequent posttreatment MR studies. The histology of primary tumors included various types of hepatocellular carcinoma (HCC) (four patients: fibrolamellar HCC [one patient], HCC [two patients], mixed HCC/cholangiocarcinoma [one patient]) and liver metastases (four patients: untyped islet cell tumor [two patients], gastrinoma [one patient], carcinoid [one patient]). Response to chemoembolization was determined by three assessments: MR response, serial imaging response, and clinical response. The appearance of MR response to chemoembolization was determined based on the correlation with clinical and serial imaging response. The MR response of lesions that showed good clinical response included: increase in signal intensity on T1-weighted images (three patients), decrease in signal intensity on T2-weighted images (three patients), and negligible or minimal enhancement on immediate postgadolinium images (four patients) after chemoembolization. The most marked change in lesion appearance was observed in lesions < 1 cm, which had intense homogeneous enhancement on pretreatment MR studies and negligible enhancement on initial posttreatment MR examinations. MR response of lesions that showed moderate clinical response demonstrated a variety of lesion appearances from substantial change to minimal change. MR response of lesions that showed poor clinical response demonstrated no change in lesion appearances compared with the pretreatment MR study. Our results demonstrated change in appearance of liver lesions between pre- and post-hepatic-arterial chemoembolization MR studies. MR response correlated with response determined by serial imaging studies and clinical findings.     

Magnetic resonance imaging of pyomyositis in 43 cases

PURPOSE: To describe the magnetic resonance imaging (MRI) findings in pyomyositis. METHODS AND MATERIALS: Forty-three patients with proven muscle infection (30 males, 13 females) ranging in age from 14 to 86 years (mean 42 years) were studied with MRI. The initial clinical diagnose were soft tissue infection (n=27), neoplasm (n=12), thrombophlebitis (n=3), and lymphedema (n=1). Spin-echo T1- and T2-weighted images were obtained in all cases and STIR sequence in 6. Spin-echo T1-weighted images after Gd-DTPA injection were obtained in 16 cases. The signal intensity findings, the extent of the abnormalities in the soft tissue (muscle, fascial and subcutaneous involvement), the presence of fluid collections, and the involvement of neighbouring bone and joint were reviewed retrospectively. RESULTS: A hyperintense signal on T2-weighted and STIR images were detected in all patients. Fluid collections were seen in 21 cases as localized areas of hypointensity on the T1-weighted images, and highly hyperintense areas on the T2-weighted images. In four patients a rim of high signal intensity was seen around the fluid collection on the T1-weighted images. On contrast-enhanced T1-weighted images there was diffuse enhancement in the patients without fluid collections that was heterogeneous in seven and homogeneous in two. After Gd-DTPA all fluid collections showed a central area without enhancement and a well-defined enhancing peripheral rim. Involvement of adjacent structures included subcutaneous tissue (n=25), bone marrow (n=14), fascial planes (n=15) and joints (n=11). CONCLUSION: MRI is useful in the assessment of pyomyositis and in determining the location and extension. A hyperintense rim on unenhanced T1-weighted images and peripheral enhancement after Gd-DTPA are useful for identifying the number, size, and location of soft-tissue abscesses.     

Adrenocortical carcinoma: MR imaging appearance with current techniques

The purpose of the study was to define the magnetic resonance (MR) imaging appearance of adrenocortical carcinoma (ACC) with current MR techniques. Eight patients with ACC underwent high-field-strength MR imaging with the following sequences: axial T1-weighted gradient echo, fat-suppressed T1-weighted spin echo, fat-suppressed T2-weighted spin echo, and gadolinium-enhanced T1-weighted gradient echo and fat-suppressed T1-weighted spin echo. Postcontrast images were also acquired in the sagittal (six patients) and coronal (three patients) planes. Out-of-phase gradient-echo images were obtained in two patients. Lesion morphology, signal intensity features, and presence of metastatic disease were retrospectively evaluated. MR imaging features of ACC included internal hemorrhage (seven of eight patients), central necrosis (seven of eight), and peripheral enhancing nodules (seven of eight). Out-of-phase images in two of two patients demonstrated signal loss compared with in-phase images, which may be a common feature of these tumors. Liver metastases were present in four patients. Consistent MR features of ACC are Identified.     

结直肠癌的MRI初步研究

目的 探讨MRI对结直肠癌检查的可行性及其价值。方法 对38例经临床拟诊为结直肠癌患者行MR检查,检查前经直肠灌水300—1000ml。分别行轴面平扫,轴面、矢状面和冠状面3个平面增强扫描及水成像。结果 38例中经手术病理证实的结直肠癌31例,5例表现为腔内局限性软组织肿块,26例表现为肠壁不规则增厚,肠腔环形狭窄环绕肠腔1周或部分,平扫T1WI上呈等信号,T2WI上30例呈略高信号,1例呈明显高信号;钆喷替酸葡甲胺(Gd—DTPA)增强扫描病灶均明显强化。5例平扫SE序列T1WI上病灶周围脂肪间隙内见斑片状低信号。增强后病变段肠壁外缘光滑12例,不光滑或有结节影向外突出19例。结直肠水成像满意的24例中显示为病变部位肠腔内不规则充盈缺损14例,10例病变远侧端呈“袖口征”及“截断征”,近侧端未显示。MRI可以正确识别31例经病理证实的结直肠癌中的30例和7例非结直肠癌中的4例,诊断的敏感度、特异度和准确度分别为96．8％、57．1％和89．5%。MRI对结直肠癌T分期的准确度为83．9％(26／31),其中对T1～2期为75．0％(9／12)、对13期为88．2％(15／17)、对T4期为100％(2／2)。结论 MRI可以从整体上显示结直肠癌的纵向和横向侵犯,可以较准确地判断肿瘤在肠壁的浸润深度,水成像最大信号强度投影(MIP)重建可部分替代钡灌肠检查,为制定临床治疗方案提供有益的指导。     

Tuberculous infection of the wrist: MRI features

OBJECTIVE: The objective of our study was to define the MRI features of tuberculous infection of the wrist. MATERIALS AND METHODS: We present the MRI findings of eight patients with tuberculous infection of the wrist. Spin-echo T1-weighted, gradient-echo T2(*)-weighted, and fast spin-echo T2-weighted sequences were performed for all patients. Gadolinium-enhanced MR images were obtained in seven patients. All images were evaluated for the characteristics of tuberculous infection of the wrist, including the presence of synovial thickening around the joints and tendons, signal intensity of the thickened tenosynovium and synovium on the T2-weighted images, synovial fluid collection in the tendon sheath, small low-signal and nonenhanced foci in the synovial fluid, bone erosion, osteomyelitis, and encasement of the median nerve. RESULTS: The tuberculous infection involved the right (n = 6) and left (n = 2) wrists. All patients had synovial thickening around the flexor and extensor tendons with synovial fluid collection in the tendon sheath. The thickened tenosynovium and synovium revealed low signal intensity on T1-weighted images, intermediate to low signal intensity on T2- and T2(*)-weighted images, and enhancement on contrast-enhanced MR images. The synovial fluid showed intermediate to low signal on T1-weighted images and homogeneous or heterogeneous high signal intensity on T2- and T2(*)-weighted images. Multiple small foci of low signal intensity and nonenhancement scattered in the synovial fluid were present in seven patients. Bone erosion occurred in seven patients, osteomyelitis was seen in six patients, and encasement of the median nerve was found in three patients. CONCLUSION: Characteristic MRI findings of tuberculous infection of the wrist include synovial thickening around the flexor and extensor tendons and synovial fluid collection that contains small low-signal and nonenhanced foci in the tendon sheath. Bone erosion, osteomyelitis, and median nerve encasement are also frequently present. These characteristic manifestations are helpful in diagnosing this disease entity.     

Tuberculosis of the pancreas: MRI features

OBJECTIVE: The purpose of this study was to describe the MRI features of tuberculosis of the pancreas. CONCLUSION: Pancreatic tuberculosis can be focal or diffuse. If focal, it presents as a sharply delineated mass located in the pancreatic head, showing heterogeneous enhancement. Lesions are hypointense on fat-suppressed T1-weighted images and a mixture of hypo- and hyperintense on T2-weighted images. The appearances of common bile duct and main pancreatic duct are normal. Diffuse involvement is characterized by pancreatic enlargement with narrowing of the main pancreatic duct and heterogeneous enhancement. Signal intensity abnormalities indicating diffuse involvement include hypointensity on fat-suppressed T1-weighted images and hyperintensity on T2-weighted images.     

MR findings of renal cortical necrosis

PURPOSE: Evaluating the MR findings of renal cortical necrosis was the purpose of this study. METHOD: Eight series of T1-/T2-weighted (n = 8) and contrast-enhanced T1-weighted (n = 4) MR images in six patients with renal cortical necrosis diagnosed by renal biopsy (n = 4) or on clinical grounds (n = 2) were reviewed. In those who had follow-up MRI (n = 2) or comparable CT (n = 3), interval changes of MR findings and comparison with CT images were done. RESULTS: Swollen kidney with dark signal intensity rim involving the inner cortex and column of Bertin was noted on T2-and T1-weighted images. It was more conspicuous on T2-weighted images. The lesion did not enhance and was differentiated from uninvolved renal parenchyma. In the follow-up MRI, thickened dark signal intensity was more prominent and proved to be calcification or fibrosis. CONCLUSION: MRI, especially T2-weighted and contrast-enhanced T1-weighted imaging, was helpful in evaluating renal cortical necrosis.     

Cross-sectional imaging of primary osseous hemangiopericytoma

The aim of this study was to assess cross-sectional imaging features and the value of CT and MRI in primary hemangiopericytoma of bone. In five patients with histologically proven primary osseous hemangiopericytoma CT and MR scans were evaluated retrospectively. Both CT and MRI were available in four patients each. In three patients both imaging techniques were available. On CT primary hemangiopericytoma of bone presents as an expansive lytic lesion with bone destruction and inhomogeneous contrast enhancement. Magnetic resonance imaging depicts osseous hemangiopericytoma as hyperintense lesion on T2-weighted images with intermediate signal intensity on T1-weighted images. Curvilinear tubular structures of signal void in the tumor matrix on T1-weighted images and corresponding hyperintense structures on T2-weighted and on fat-suppressed short tau inversion recovery images were present in three patients. Although cross-sectional imaging findings are non-specific, they add to the diagnosis and provide valuable information about the extent of bone destruction and local tumor spread in patients with primary osseous hemangiopericytoma. While CT demonstrates the extent of bone destruction best, MRI better visualizes medullary and soft tissue extension of the tumor. Curvilinear signal abnormalities support the diagnosis of hemangiopericytoma of bone. This imaging pattern is best visualized on fat-suppressed or contrast enhanced T1-weighted MR images.     

CT and MRI features of low-grade fibromyxoid sarcoma in the shoulder of a pediatric patient

We report the computed tomography (CT) and magnetic resonance imaging (MRI) features of a 10-year-old boy with low-grade fibromyxoid sarcoma (LGFMS) in the shoulder and correlate them with the clinicopathological features. LGFMS, a rare soft tissue sarcoma with bland histological features and paradoxically aggressive behavior, tends to occur in superficial regions and in children more than previously recognized. To date, few imaging studies have been reported, particularly in pediatric patients. In this case, precontrast CT showed a low- to isodensity mass and punctate calcification. On contrast-enhanced CT, heterogeneous enhancement was seen. MRI findings correlated well with the pathological features of the tumor. The myxoid area showed high signal intensity on T2-weighted MR images and heterogeneous enhancement after administration of contrast material; the hypercellular area demonstrated lower signal intensity on T2-weighted MR images and slight enhancement.     

Diffuse vertebral body edema due to calcified intraspongious disk herniation

We describe the case of a patient with a recent history of high back pain, with magnetic resonance imaging (MRI) of the thoracic spine showing intervertebral disk herniation into the spongious bone of the vertebral body of T9 that might have caused diffuse, low signal intensity on fluid-attenuated inversion recovery T1-weighted (FLAIR-T1W) images, high signal intensity magnetic resonance (MR) on T2-weighted (T2W) images and T2-weighted fat-suppressed images (T2W-FSIs) and marked enhancement on the vertebral body of T9 with gadolinium on T1-weighted fat-suppressed images (T1W-FSIs) images. Those findings suggested diffuse edema and might be indistinguishable from tumoral or inflammatory diseases, but the plain films and the reformatted sagittal computed tomography scans of the thoracic spine were helpful to show a calcified part of the intervertebral disk migrating into the vertebral body of T9. The patient made full recovery from the symptoms after conservative treatment and at the follow-up MRI showed normalization of the bone marrow signal intensity of the vertebral body of T9.     

Improved detection of enhancing and nonenhancing lesions of multiple sclerosis with magnetization transfer.

PURPOSETo determine whether magnetization transfer imaging can improve visibility of contrast enhancement of multiple sclerosis plaques.METHODSFifty-nine enhancing and 63 nonenhancing lesions in 10 patients with multiple sclerosis were evaluated to calculate contrast-to-noise ratios on conventional T1-weighted and T1-weighted magnetization transfer images. The signal intensity of the lesion and the background (white matter) were measured on precontrast T1-weighted and T1-weighted magnetization transfer images (800/20/1 [repetition time/echo time/excitations]) and on postcontrast T1-weighted and T1-weighted magnetization transfer images. Mean contrast-to-noise ratios was calculated for all lesions.RESULTSThe contrast-to-noise ratio was significantly higher for enhancing and nonenhancing lesions on T1-weighted magnetization transfer images than on conventional T1-weighted images. For enhancing lesions, the contrast-to-noise ratio was significantly higher on postcontrast T1-weighted magnetization transfer images, 32 +/- 2 compared with 21 +/- 2 on conventional T1-weighted images. Fifty of the 59 enhancing lesions were seen on both the T1-weighted and the T1-weighted magnetization transfer images. Nine enhancing lesions were seen only on the postcontrast T1-weighted magnetization transfer images. In addition, of 63 nonenhancing lesions seen on proton-density, T2-weighted, and T1-weighted magnetization transfer images, 16 were not seen on the conventional T1-weighted images. Seven of the 63 nonenhancing lesions and 7 of the 59 enhancing lesions had high signal intensity on the precontrast T1-weighted magnetization transfer images suggestive of lipid signal, a finding not seen on the conventional precontrast T1-weighted images.CONCLUSIONMagnetization transfer improves the visibility of enhancing multiple sclerosis lesions, because they have a higher contrast-to-noise ratio than conventional postcontrast T1-weighted images. High signal intensity on both nonenhancing and enhancing lesions noted only on precontrast T1-weighted magnetization transfer suggests a lipid signal was unmasked. If magnetization transfer is used in multiple sclerosis patients, a precontrast magnetization transfer image is necessary.