Hepatic nodules in Budd-Chiari syndrome: imaging features

PURPOSE: To analyze the imaging features of nodules associated with Budd-Chiari syndrome. MATERIALS AND METHODS: The authors retrospectively studied images obtained in 23 patients with liver nodules who were being followed up for Budd-Chiari syndrome. Doppler ultrasonography was performed in all patients, computed tomography in 16, and magnetic resonance (MR) imaging in 20. The following lesion features were evaluated: location, number, size, vascularization, qualitative signal intensity at MR imaging, and homogeneity. Nodules were diagnosed on the basis of histopathologic findings or clinical and biologic data with no change at imaging during 2-year follow-up. RESULTS: All patients had histopathologic features of chronic Budd-Chiari syndrome. Four patients had hepatocellular carcinoma (HCC), with one to three lesions. The mean diameter of the largest HCC lesion in each patient was 7.3 cm. All HCC lesions were heterogeneous and had high signal intensity on T2-weighted MR images. Nineteen patients had multiple benign regenerative nodules, most of which were smaller than 4 cm. Most nodules were homogeneous and hyperintense on T1- and T2-weighted images. In 15 patients, nodules were hypervascular in the arterial phase. CONCLUSION: In patients with chronic Budd-Chiari syndrome, multiple (> 10) small (< 4-cm) lesions are suggestive of benignity.     

Venous sinus occlusive disease: MR findings.

PURPOSETo study MR patterns of venous sinus occlusive disease and to relate them to the underlying pathophysiology by comparing the appearance and pathophysiologic features of venous sinus occlusive disease with those of arterial ischemic disease.METHODSThe clinical data and MR examinations of 26 patients with venous sinus occlusive disease were retrospectively reviewed with special attention to mass effect, hemorrhage, and T2-weighted image abnormalities as well as to abnormal parenchymal, venous, or arterial enhancement after intravenous gadopentetate dimeglumine administration. Follow-up studies when available were evaluated for atrophy, infarction, chronic mass effect, and hemorrhage.RESULTSMass effect was present in 25 of 26 patients. Eleven of the 26 had mass effect without abnormal signal on T2-weighted images. Fifteen patients had abnormal signal on T2-weighted images, but this was much less extensive than the degree of brain swelling in all cases. No patient showed abnormal parenchymal or arterial enhancement. Abnormal venous enhancement was seen in 10 of 13 patients who had contrast-enhanced studies. Intraparenchymal hemorrhage was seen in nine patients with high signal on T2-weighted images predominantly peripheral to the hematoma in eight. Three overall MR patterns were observed in acute sinus thrombosis: 1) mass effect without associated abnormal signal on T2-weighted images, 2) mass effect with associated abnormal signal on T2-weighted images and/or ventricular dilatation that may be reversible, and 3) intraparenchymal hematoma with surrounding edema.CONCLUSIONMR findings of venous sinus occlusive disease are different from those of arterial ischemia and may reflect different underlying pathophysiology. In venous sinus occlusive disease, the breakdown of the blood-brain barrier (vasogenic edema and abnormal parenchymal enhancement) does not always occur, and brain swelling can persist up to 2 years with or without abnormal signal on T2-weighted images. Abnormal signal on T2-weighted images may be reversible and does not always indicate infarction.     

Acute and subacute intracerebral hemorrhages: comparison of MR imaging at 1.5 and 3.0 T--initial experience

PURPOSE: To assess and describe the appearance of intracerebral hemorrhage (ICH) at 3.0-T magnetic resonance (MR) imaging as compared with the appearance of this lesion type at 1.5-T MR imaging. MATERIALS AND METHODS: Sixteen patients with 21 parenchymal ICHs were examined. ICHs were classified as hyperacute, acute, early subacute, late subacute, or chronic. Patients underwent 1.5- and 3.0-T MR imaging with T2-weighted fast spin-echo, fluid-attenuated inversion-recovery (FLAIR), and T1-weighted spin-echo (1.5-T) and gradient-echo (3.0-T) sequences within 4 hours of each other. The central (ie, core) and peripheral (ie, body) parts of the ICHs were analyzed quantitatively by using contrast-to-noise ratio (CNR) calculations derived from signal intensity (SI) measurements; these values were statistically evaluated by using the Mann-Whitney U test. Two readers qualitatively determined SIs of the cores and bodies of the ICHs, degrees of apparent susceptibility artifacts, and lesion ages. The chi(2) test was used to determine statistically significant differences. RESULTS: With the exception of the bodies of late subacute ICHs at 3.0-T T2-weighted imaging, which had increased positive CNRs and SI scores (P .05). With the exception of minor susceptibility artifacts seen in acute and early subacute ICHs at 3.0-T T1-weighted gradient-echo imaging, no susceptibility artifacts were noticed. The ages of most lesions were identified correctly without significant differences between the two field strengths (P >.05), with the exception of the ages of acute ICHs, which were occasionally misinterpreted as early subacute lesions at 3.0 T. CONCLUSION: At 3.0 T, all parts of acute and early subacute ICHs had significantly increased hypointensity on FLAIR and T2-weighted MR images as compared with the SIs of these lesions at 1.5 T. However, 1.5- and 3.0-T MR images were equivalent in the determination of acute to late subacute ICHs.     

Osteomyelitis in children: gadolinium-enhanced MR imaging.

Fifteen pediatric patients with biopsy- or culture-proved nonspinal osteomyelitis were studied with magnetic resonance (MR) imaging. Osteomyelitis was acute in seven patients, subacute in three, and chronic in five. Four patients had subperiosteal abscesses, one had a large associated soft-tissue abscess, and one had an intraosseous (Brodie) abscess. Areas of active inflammation had decreased marrow signal intensity on T1-weighted images, increased signal intensity on T2-weighted images, and enhancement on T1-weighted images obtained after gadopentetate dimeglumine administration (n = 10). Abscesses were rim enhancing (n = 3) or not (n = 2) with gadolinium-enhanced MR imaging. Nonenhancing areas presumably represented necrotic material. Gadolinium-enhanced MR imaging assisted in definition of the presence and extent of nonvascularized fluid collections within the bone and/or adjacent soft tissues and the extent of bone involvement in patients with chronic osteomyelitis. It also helped guide surgical debridement of intraosseous disease (n = 7) and open or percutaneous drainage of subperiosteal or soft-tissue fluid collections (n = 5).     

Hepatic outflow obstruction: enhancement patterns of the liver on MR angiography

Our purpose was to present the enhancement patterns of the liver on MR angiography in patients with hepatic outflow obstruction. Twenty-three patients with Budd-Chiari syndrome (4 in acute stage and 19 in chronic stage of the disease) were examined with 3D contrast-enhanced MR angiography. During early and late portal venous phase of MR angiography the pattern of parenchymal enhancement was assessed on source images. The enhancement patterns were evaluated under 4 groups as following: (a) central (b) peripheral (c) patchy and (d) homogeneous enhancement. The morphologic changes in the liver (lobar hypertrophy or atrophy, hepatic surface irregularities) were also recorded. In the acute stage global liver enlargement (75%) with caudate hypertrophy (100%) and central enhancement of the liver (75%) were suggestive findings of the hepatic outflow obstruction. The left lobe hypertrophy (53%) associated with the caudate lobe hypertrophy (72%) and irregular surface (26%) were predominant in the chronic stage of the disease. The enhancement patterns seen in chronic disease were variable and reflected the persistent stasis of the portal blood flow (patchy enhancement in 32% of the patients) or the altered hemodynamics of the liver due to the development of subcapsular collaterals (peripheral enhancement in 21% of the patients). Homogeneous enhancement of the liver in Budd-Chiari syndrome may indicate the chronicity of the outflow obstruction (37%) and shows a more stable hepatic perfusion that occurs after the formation of intra and extrahepatic collateral veins. The morphological and perfusional features on multiphase contrast-enhanced MR angiography are valuable in understanding the effects of the hepatic outflow obstruction on the liver parenchyma.     

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.     

Magnetic resonance imaging of bowel ischemia induced by ligation of superior mesenteric artery and vein in a cat model

OBJECTIVE: To assess the usefulness of magnetic resonance (MR) imaging for detecting bowel ischemia with strangulation compared with histopathologic findings in an experimental cat model. MATERIALS AND METHODS: Fourteen cats were assigned to the normal control group (n = 3), acute ischemic group (induced by ligation of superior mesenteric vessels for 3 hours, n = 7), and subacute ischemic group (induced by ligation of superior mesenteric vessels for 10 hours, n = 4). Using a 4.7-T MR scanner, contrast-enhanced T1-weighted images were obtained at 0, 10, 20, 30, and 60 minutes after bolus injection of contrast media. T1- and T2-weighted images were obtained from the extracted bowel wall and compared with histopathologic findings. RESULTS: On contrast-enhanced MR images, the target-like bowel wall layers were clearly demonstrated and the submucosal layer showed the most prominent enhancement. At 10 minutes after administration of contrast media, the subacute ischemic group showed significantly lower enhancement of the submucosal layer than the normal or acute ischemic group (P <0.05). On T1-weighted images, there were not significant differences between the normal and ischemic bowel groups (P >0.05). On T2-weighted images, the signal intensity of all layers of acute ischemic bowel wall was significantly higher than that of the normal control or subacute ischemic group (P <0.05). CONCLUSION: Delayed contrast-enhanced MR images and T2-weighted images were helpful for detecting subacute and acute bowel ischemia with strangulation, respectively.     

Assessment of myocardial infarction in humans with (23)Na MR imaging: comparison with cine MR imaging and delayed contrast enhancement

PURPOSE: To demonstrate the feasibility of sodium 23 ((23)Na) magnetic resonance (MR) imaging for assessment of subacute and chronic myocardial infarction and compare with cine, late enhancement, and T2-weighted imaging. MATERIALS AND METHODS: Thirty patients underwent MR imaging 8 days +/- 4 (subacute, n = 15) or more than 6 months (chronic, n = 15) after myocardial infarction by using a (23)Na surface coil with a double angulated electrocardiogram-triggered three-dimensional gradient-echo sequence at 1.5 T. In addition, cine, inversion-recovery gradient-echo, and, in the subacute group, T2-weighted images (n = 9) were obtained. Myocardial infarction mass was depicted as elevated signal intensity or wall motion abnormalities and expressed as a percentage of total left ventricular mass for all modalities. Correlations were tested with correlation coefficients. RESULTS: All patients after subacute infarction and 12 of 15 patients with chronic infarction had an area of elevated (23)Na signal intensity that significantly correlated with wall motion abnormalities (subacute; r = 0.96, P <.001, and chronic; r = 0.9, P <.001); three patients had no wall motion abnormalities or elevated (23)Na signal intensity. Only 10 patients in the subacute and nine in the chronic group revealed late enhancement; significant correlation with (23)Na MR imaging occurred only in subacute group (r = 0.68, P <.05). Myocardial edema in subacute infarction correlated (r = 0.71, P <.05) with areas of elevated (23)Na signal intensity but was extensively larger. CONCLUSION: (23)Na MR imaging demonstrates dysfunctional myocardium caused by subacute and chronic myocardial infarction.     

Magnetic resonance imaging of myositis ossificans: analysis of seven cases

Myositis ossificans typically presents as soft tissue swelling with progressive ossification on radiographs. Since magnetic resonance imaging (MRI) is commonly used to evaluate soft tissue masses, we analyzed eight MR examinations in seven patients with myositis ossificans to determine if typical patterns were present. One acute lesion had homogeneous intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Two subacute lesions had low signal intensity margins with slightly increased signal intensity centers on T1-weighted images and very high signal intensity on T2-weighted images. Five chronic lesions had two different patterns. All five were well-defined with low signal intensity borders. Three had signal intensity patterns characteristic of fat on T1-weighted and T2-weighted images. The other two lesions had intermediate signal intensity on T1-weighted images and slightly increased signal intensity on T2-weighted images.We conclude that typical MR appearances of myositis ossificans do exist. A low signal intensity rim is a common finding. However, these patterns are not unique to myositis ossificans and resemble those that have been reported in other lesions. It is important to be aware of the spectrum of MR findings of myositis ossificans when considering the differential diagnosis of a soft tissue mass.     

Benign hepatic nodules in Budd-Chiari syndrome: radiologic-pathologic correlation with emphasis on the central scar

OBJECTIVE: The purpose of this study was to determine the imaging features of benign hepatic nodules in patients with Budd-Chiari syndrome and to correlate them with pathologic findings, with special attention placed on the presence of a central scar. MATERIALS AND METHODS: Imaging findings of 59 benign hepatic nodules in four patients with chronic Budd-Chiari syndrome were analyzed retrospectively, and radiologic- pathologic correlation was performed in three patients with 50 hepatic nodules who underwent liver transplantation. All patients underwent multiphasic helical CT. In three patients with 29 lesions, MR imaging, including a multiphasic dynamic study, was performed. The CT and MR imaging findings in these patients were compared with those of 103 small hepatocellular carcinomas in 56 other patients (54 of them displayed chronic hepatitis or liver cirrhosis associated with viral hepatitis but none had Budd-Chiari syndrome). Image analysis was performed by two radiologists with no knowledge of the diagnosis. RESULTS: All patients with Budd-Chiari syndrome exhibited multiple benign nodules up to 3 cm in diameter, and 42 of 59 lesions were hypervascular. Microscopically, 15 of 32 nodules demonstrated a central scar; moreover, some nodules closely resembled focal nodular hyperplasia. Frequencies of hyperintensity on T1-weighted images (14/29 vs 25/103), hypointensity on T2-weighted images (7/29 vs 1/103), and the presence of a central scar (6/59 vs 1/103) were significantly higher in benign nodules than in hepatocellular carcinomas (p < 0.05; Fisher's exact test). Moreover, for lesions larger than 1 cm, imaging studies revealed a central scar in six of 15 benign lesions. CONCLUSION: Benign hepatic nodules in patients with in Budd-Chiari syndrome are usually small, multiple, and hypervascular. The presence of a central scar is a characteristic feature in those larger than 1 cm in diameter.     

Radiation-induced liver injury showing low intensity on T2-weighted images noted in Budd-Chiari syndrome

PURPOSE: Although it is documented that radiation can cause density or intensity changes on computed tomography or MR imaging in the irradiated hepatic parenchyma, few researchers have reported or understood the MR presentation of changes in hepatic parenchyma following radiotherapy in the patient with Budd-Chiari syndrome. The purpose of this study was to investigate the MR appearance of hepatic radiation injury in Budd-Chiari syndrome and to consider the underlying pathophysiology. MATERIALS AND METHODS: The MR examinations of two patients with Budd-Chiari syndrome were compared with those of 11 patients without Budd-Chiari syndrome. The two groups, both of which suffered from hepatocellular carcinoma, underwent 50-72 Gy of proton-beam irradiation during a period of 14-43 days. Examinations including T1- and T2-weighted imaging, superparamagnetic iron oxide-enhanced imaging, and dynamic study were performed 3-10 weeks after the end of irradiation. RESULTS: Radiation-induced hepatic injury was observed as a low-intensity area on T2-weighted images and on delayed phase images of dynamic study in the Budd-Chiari patients, and as iso- or high-intensity areas on both images in the patients without Budd-Chiari syndrome. US-guided needle biopsy from the irradiated area in one patient with Budd-Chiari syndrome revealed mostly necrotic tissue and fibrous tissue. CONCLUSION: These MR features of hepatic radiation injury in Budd-Chiari syndrome were considered to be due to severe hepatic fibrosis.     

Nontumorous hepatic arterial-portal venous shunts: MR imaging findings

PURPOSE: To determine the magnetic resonance (MR) imaging findings of small nontumorous hepatic arterial-portal venous (arterioportal) shunts in the liver. MATERIALS AND METHODS: MR images in 25 patients with 38 small nontumorous arterioportal shunts verified with surgery or follow-up imaging were included in this study. The causes of arterioportal shunts were iatrogenic causes in 11 patients and/or cirrhotic changes in the remaining patients. Nonenhanced T1- and T2-weighted images and multiphase contrast material-enhanced dynamic images were retrospectively reviewed and compared with conventional hepatic arteriograms to determine the MR characteristics related to the focal hemodynamic changes. RESULTS: On arterial-dominant-phase dynamic MR images, 29 (76%) of the 38 arteriographically suggested nontumorous arterioportal shunts displayed abnormal findings distinguished against the surrounding hepatic parenchyma, including wedge-shaped (n = 14), nodular (n = 9), or irregularly outlined (n = 6) areas of focal contrast enhancement. The signal intensity on nonenhanced T1- and T2-weighted images of the corresponding areas appeared unremarkable except for three wedge-shaped high-signal-intensity areas (three [8%] of 38) on T2-weighted images accompanied by prolonged contrast enhancement. Most (24 [83%] of 29) areas of abnormal signal intensity were located at the periphery of the liver parenchyma. CONCLUSION: A small nontumorous arterioportal shunt should be considered one of the causes of focal parenchymal hyperperfusion abnormalities on contrast-enhanced dynamic MR images of the liver in the absence of abnormal signal intensity on static MR images.     

Nodular fasciitis: correlation of MRI findings and histopathology

OBJECTIVE: To compare the histopathology of nodular fasciitis (NF) with the magnetic resonance imaging (MRI) findings in order to evaluate the basis of the MR signal characteristics. DESIGN AND PATIENTS: Ten patients with NF, nine females and 1 male, with an age ranging from 13 to 58 years (mean 26.8 years) were studied. MRI findings, available in all 10 patients, were compared with the histopathology in nine patients, and an area-to-area comparative study of the whole specimen section histopathology and MRI was performed in two patients. RESULTS: On the basis of an excisional biopsy or resection specimen, the nine lesions were classified into myxoid ( n=4), cellular ( n=3) and fibrous ( n=2) subtypes. Four myxoid lesions with a subcutaneous location showed a homogeneous SI comparable with muscle on T1-weighted images, high SI on T2-weighted images, and had homogeneous enhancement. One cellular lesion presented with homogeneous, slightly higher SI than muscle on T1-weighted images and inhomogeneous, high SI on T2-weighted images. Alcian blue stain of the whole specimen section revealed the lesion had two parts corresponding to different enhancement patterns on MRI. The blue-stained myxoid part showed markedly diffuse enhancement, while the non-stained cystic space had only peripheral enhancement. Two other cellular lesions had the same appearance on both T1- and T2-weighted images and showed inhomogeneous, diffuse enhancement. One fibrous subtype lesion presented with inhomogeneous, overall slightly higher SI than muscle on T1-weighted images, lower SI at the periphery and high SI in the center on STIR images and only peripheral enhancement. Microscopy and CD-31 staining of the lesion showed more extracellular matrix, with poor vascularity in the center and more collagenous matrix with higher vascularity at the periphery. CONCLUSION: Although similar findings were found in some lesions, the large histologic variability of NF hampers the definition of a prototype of NF on MRI. However, the MRI appearance of the myxoid subtype is rather characteristic. Histologic findings reflect the different SI characteristics and enhancement pattern on MRI.     

MR imaging of hepatic metastases caused by neuroendocrine tumors: comparing four techniques

OBJECTIVE: The aim of our prospective study was to assess the MR imaging characteristics of hepatic metastases of neuroendocrine tumors and to determine the optimal MR sequence for their detection. SUBJECTS AND METHODS: Thirty-seven consecutive patients with liver metastases from neuroendocrine tumors underwent 1.5-T MR imaging of the liver comprising T2-weighted fast spin-echo with respiratory monitoring, breath-hold T2-weighted single-shot fast spin-echo, and T1-weighted gradient-recalled echo sequences before and after the injection of gadoterate dimeglumine. Images were reviewed independently by three observers for the number, location, and pattern of signal and enhancement of metastases. RESULTS: A total of 359 metastases were detected, 279 on T2-weighed fast spin-echo, 231 on T2-weighed single-shot fast spin-echo, 272 on unenhanced T1-weighted, 322 on hepatic arterial phase, and 228 on portal venous phase images. Hepatic arterial phase images revealed the greatest number of metastases in 70% of patients, including 35 metastases seen only on this sequence, and was significantly superior to the unenhanced T1-weighted and portal venous phase sequences (p < 0.01). The lesion-to-liver contrast was significantly greatest with T2-weighed fast spin-echo sequences. The enhancement patterns of metastases were predominantly hypervascular, hypovascular, peripheral with progressive fill-in, and delayed in, respectively, 27, four, four, and two patients. Most metastases with peripheral enhancement and progressive fill-in were heterogeneous on T2-weighted images and were without globular peripheral enhancement. CONCLUSION: Hepatic metastases of neuroendocrine tumors had a typical hypervascular pattern in 73% of patients. Hepatic arterial phase and fast spin-echo T2-weighed sequences are the most sensitive.     

Magnetic resonance imaging of localized giant cell tumour of the tendon sheath (MRI of localized GCTTS)

The objective of this study was to evaluate the appearance of localized giant cell tumour of the tendon sheath (GCTTS) on unenhanced and Gd-enhanced MR images. MR images of 13 histologically proven cases of localized GCTTS were evaluated for mean size, location, homogeneity and signal intensity (SI) on both T1- and T2-weighted images, and enhancement pattern. All lesions except 1 affected young adults. On T1- and T2-weighted images, lesions showed predominantly low SI equal to or slightly higher than skeletal muscle. On Gd-enhanced T1-weighted images, strong homogeneous enhancement was seen. These findings reflect the underlying histological composition of the lesion; haemosiderin deposition in xanthoma cells, shortening T2-relaxation time, and abundant collagenous proliferation are responsible for low SI on T1- and T2-weighted images. Strong homogeneous enhancement originates from numerous proliferative capillaries in the collagenous stroma. We conclude that these characteristic MR features, together with clinical information, are a valuable diagnostic tool in offering a correct preoperative diagnosis. Received 14 May 1996; Accepted 5 June 1996     

MR imaging of brain contusions: a comparative study with CT

Ninety-eight brain contusions in 17 patients served as a data base for a comparative study of MR and CT for defining brain contusions. MR was the more sensitive technique, detecting 98% of the brain contusions compared with only 56% by CT. CT was slightly better for showing hemorrhagic components, documenting 77% of hemorrhages compared with 71% for MR. The appearance of the contusions on MR was variable, depending on the T1- and T2-weighting of the images and the constituents of the contusions, such as edema, hemorrhage, and encephalomalacia. On MR, hemorrhagic components appeared as high signal on T1-weighted images and as either low or high signal on T2-weighted images, depending on the age of the hemorrhage. The approximate ages of hemorrhagic contusions were often suggested by their appearance on T1- and T2-weighted images. CT is very effective for evaluating acute head trauma, but MR is recommended for documenting brain contusions during the subacute and chronic stages of head injuries.     

The cisterna chyli: enhancement on delayed phase MR images after intravenous administration of gadolinium chelate

PURPOSE: To retrospectively evaluate cisterna chyli (CC) enhancement on magnetic resonance (MR) images obtained after intravenous administration of a gadolinium-based contrast agent. MATERIALS AND METHODS: This retrospective HIPAA-compliant study of 1.5-T MR imaging findings was institutional review board approved; informed patient consent was waived. All MR examinations involved the acquisition of heavily T2-weighted single-shot fast spin-echo (SSFSE) images and three-dimensional (3D) gradient-echo images obtained before and during the arterial, venous, and 3-5-minute delayed phases after intravenous bolus injection of gadopentetate dimeglumine. Included were the data of 59 patients (37 men, 22 women; mean age, 59 years) who had a CC 4 mm or greater in transverse diameter, which was identified as a tubular structure with fluid signal intensity (SI) on SSFSE images. The SI of the CC relative to the spinal canal (SC) was noted and was measured on 3D gradient-echo images obtained during all phases. The Student t test was performed for statistical evaluations. RESULTS: Mean CC-SC SI ratios on nonenhanced, arterial phase, venous phase, and delayed phase images were 0.92, 0.98, 0.99, and 2.13, respectively. The CC had low SI on all 3D gradient-echo images obtained during the nonenhanced, arterial, and venous phases and high SI, similar to the azygos vein SI, on all delayed phase images. The CC-SC SI ratio during the delayed phase was significantly higher than that during the other phases (P<.001). CONCLUSION: The CC has minimal or no enhancement on arterial phase and venous phase images but intense enhancement--similar to the enhancement of veins--on delayed phase images. Comparison of delayed phase images with SSFSE and venous phase images may help to distinguish the CC seen on delayed phase images from lymph nodes, the azygos vein, or esophageal varices.     

MRI findings in spinal subdural and epidural hematomas

BACKGROUND: Spinal hematomas are rare entities that can be the cause of an acute spinal cord compression syndrome. Therefore, an early diagnosis is of great importance. PATIENTS AND METHODS: From 2001 to 2005 seven patients with intense back pain and/or acute progressive neurological deficit were studied via 1.5 T MRI (in axial and sagittal T1- and T2-weighted sequences). Follow-up MRI was obtained in six patients. RESULTS: Four patients showed the MRI features of a hyperacute spinal hematoma (two spinal subdural hematoma [SSH] and two spinal epidural hematoma [SEH]), isointense to the spinal cord on T1- and hyperintense on T2-weighted sequences. One patient had an early subacute SEH manifest as heterogeneous signal intensity with areas of high signal intensity on T1- and T2-weighted images. Another patient had a late subacute SSH with high signal intensity on T1- and T2-weighted sequences. The final patient had a SEH in the late chronic phase being hypointense on T1- and T2-weighted sequences. DISCUSSION: MRI is valuable in diagnosing the presence, location and extent of spinal hematomas. Hyperacute spinal hematoma and the differentiation between SSH and SEH are particular diagnostic challenges. In addition, MRI is an important tool in the follow-up in patients with conservative treatment.     

Budd-Chiari syndrome: dynamic CT

A retrospective multi-institutional study was carried out on a series of 38 patients with histologically proved Budd-Chiari syndrome: Five patients had acute disease, and 33 had subacute or chronic disease. All patients underwent dynamic CT scanning. Angiography was performed in 20 cases, inferior cavography in 22, and wedge-hepatic venography in 16. In all acute cases, CT showed global liver enlargement with diffuse hypodensity on plain scans and patchy enhancement after contrast material injection. Thrombosis of the three main hepatic veins was always demonstrated. In subacute or chronic disease, plain CT scans showed abnormalities of liver morphology and hypodensity either in atrophic areas (19 cases) or in the periphery of the liver (eight cases). With dynamic CT, patchy enhancement was present in 28 cases. Correlation with angiography in 15 cases revealed a normal portal blood flow in enhanced areas and an inversed portal blood flow in atrophic areas. Different morphologic and enhancement patterns on CT scans could be related to the direction of portal blood flow, which changes with different stages of Budd-Chiari syndrome.     

Denervation syndromes of the shoulder girdle: MR imaging with electrophysiologic correlation

Objective. To investigate the use of MR imaging in the characterization of denervated muscle of the shoulder correlated with electrophysiologic studies. Design and patients. We studied with MR imaging five patients who presented with shoulder weakness and pain and who underwent electrophysiologic studies. On MR imaging the distribution of muscle edema and fatty infiltration was recorded, as was the presence of masses impinging on a regional nerve. Results. Acute/subacute denervation was best seen on T2-weighted fast spin-echo images with fat saturation, showing increased SI related to neurogenic edema. Chronic denervation was best seen on T1-weighted spin-echo images, demonstrating loss of muscle bulk and diffuse areas of increased signal intensity within the muscle. Three patients showed MR imaging and electrophysiologic findings of Parsonage Turner syndrome. One patient demonstrated an arteriovenous malformation within the spinoglenoid notch, impinging on the suprascapular nerve with associated atrophy of the infraspinatus muscle. The fifth patient demonstrated fatty atrophy of the teres minor muscle caused by compression by a cyst of the axillary nerve and electrophysiologic findings of an incomplete axillary nerve block. Conclusion. MR imaging is useful in detecting and characterizing denervation atrophy and neurogenic edema in shoulder muscles. MR imaging can provide additional information to electrophysiologic studies by estimating the age (acute/chronic) and identifying morphologic causes for shoulder pain and atrophy. Received: 5 May 1999 Revision requested: 22 July 1999 Revision received: 28 July 1999 Accepted: 29 July 1999