MR Imaging of Soft Tissue Hemangioma of the Extremity

PURPOSE: To analyse the MR imaging characteristics of the soft tissue hemagiomas of the extremity. MATERIALS AND METHODS: We retrospectively reviewed histopathologically proven 18 cases of hemangiomas of the extremity including 15 cavernous hemangiomas, 2 venous hemangiomas and 1 capillary hemangioma. The lesions were frequent in female and low extremity. We analyzed the site, extent, margin, signal intensity, enhancement pattern, the homogeniety of internal architecture, and abnormal vessels near the lesion. RESULTS: The extensive lesions involving multiple muscle and tissue layers were more frequent than localized lesions (12/18). Twelve cases had ill defined margin. In most cases, the lesion was heterogeneous mass composed of nodular and septal components. The nodular component showed intermediate signal intensity in T1WI and hign signal intensity in T2WI. The setal component showed mixed inconstant signal intensity. One case of capillary hemangioma showed relatively homogeneous signal intensity than cavernous hemangioma and the main portion of 2 venous hemangiomas had mutilple tubular signal voids. At least some portion of the lesion was enhanced in all enhanced cases. CONCLUSION: The soft tissue hemangiomas of the extremity showed characteristic MR findings and MRI would be an useful method in the diagnosis of the soft tissue hemangiomas of the extremity.

MR Imaging of Anterior Cruciate Ligament Injury: Associated Findings

PURPOSE: Authors investigated the associated findings and their value in the diagnosis of anterior cruciate ligament(ACL) injury in MR image. MATERIAL AND METHODS: The knee MR images of 47 patients with ACL injury(complete; 24, partial; 23) and 61 patients with normal ACL confirmed by the knee arthroscopy or operation were reviewed retrospectively. The degree of anterior translocation of tibia and the degree of posterior cruciate ligament(PCL) buckling were evaluated. The prevalence and pattern of associated adjacent bone, ligament and meniscus injuries were studied. RESULTS: The means( +/- 2standard errors) of anterior translocation were different significantly in statistical analysis(p<0.001, student t-test) between injury group(7.51 +/- 1.16mm) and normal group(-0.56 +/- 0.92mm). In the level of 5mm of anterior translocation for the criteria of ACL injury, the sensitivity, specificity, accuracy were 78.7%, 89.5%, 84.3% for each. The means of PCL buckling ratio were also different statistically b. etween injury group(0.23 +/- 0.02) and normal group(0.17 +/- 0.01)(p<0.001). In the level of 0.20 for diagnostic criteria of ACL injury, the sensitivity, specificity, accuracy were 71.4%, 83.6%, 78.4% for each. Thirty one medial meniscus tear(66%), thirteen lateral meniscus tear(28%), ten medial collateral ligament injury(28%), one PCL injury (2%) were associated with ACL injury. The twenty nine bone marrow changes were found in twenty patients {43%) which included acutely injured seven patients. In acute cases, the bone marrow changes were depicted as diffuse or focal high signal intensity lesions in lateral femoral or tibial condyles in contrast to the changes in chronic cases depicted as focal low signal intensity lesions in variable location. Lateral femoral condylar notch depression were found in nine patients(19%) and avulsion fractures of anterior tibial spine in four patients(9%). CONCLUSION: The associated findings with ACL injury (anterior translocation, buckling of PCL, associated bone, ligament and meniscus injuries) are considered to be helpful in the diagnosis of ACL injury on Knee MR images, when the findings of anterior cruciate ligament itself are not confirmative.

MR Imaging of Soft Tissue Hemangioma of the Extremity

PURPOSE: To analyse the MR imaging characteristics of the soft tissue hemagiomas of the extremity. MATERIALS AND METHODS: We retrospectively reviewed histopathologically proven 18 cases of hemangiomas of the extremity including 15 cavernous hemangiomas, 2 venous hemangiomas and 1 capillary hemangioma. The lesions were frequent in female and low extremity. We analyzed the site, extent, margin, signal intensity, enhancement pattern, the homogeniety of internal architecture, and abnormal vessels near the lesion. RESULTS: The extensive lesions involving multiple muscle and tissue layers were more frequent than localized lesions (12/18). Twelve cases had ill defined margin. In most cases, the lesion was heterogeneous mass composed of nodular and septal components. The nodular component showed intermediate signal intensity in T1WI and hign signal intensity in T2WI. The setal component showed mixed inconstant signal intensity. One case of capillary hemangioma showed relatively homogeneous signal intensity than cavernous hemangioma and the main portion of 2 venous hemangiomas had mutilple tubular signal voids. At least some portion of the lesion was enhanced in all enhanced cases. CONCLUSION: The soft tissue hemangiomas of the extremity showed characteristic MR findings and MRI would be an useful method in the diagnosis of the soft tissue hemangiomas of the extremity.

MR Imaging of Anterior Cruciate Ligament Injury: Associated Findings

PURPOSE: Authors investigated the associated findings and their value in the diagnosis of anterior cruciate ligament(ACL) injury in MR image. MATERIAL AND METHODS: The knee MR images of 47 patients with ACL injury(complete; 24, partial; 23) and 61 patients with normal ACL confirmed by the knee arthroscopy or operation were reviewed retrospectively. The degree of anterior translocation of tibia and the degree of posterior cruciate ligament(PCL) buckling were evaluated. The prevalence and pattern of associated adjacent bone, ligament and meniscus injuries were studied. RESULTS: The means( +/- 2standard errors) of anterior translocation were different significantly in statistical analysis(p<0.001, student t-test) between injury group(7.51 +/- 1.16mm) and normal group(-0.56 +/- 0.92mm). In the level of 5mm of anterior translocation for the criteria of ACL injury, the sensitivity, specificity, accuracy were 78.7%, 89.5%, 84.3% for each. The means of PCL buckling ratio were also different statistically b. etween injury group(0.23 +/- 0.02) and normal group(0.17 +/- 0.01)(p<0.001). In the level of 0.20 for diagnostic criteria of ACL injury, the sensitivity, specificity, accuracy were 71.4%, 83.6%, 78.4% for each. Thirty one medial meniscus tear(66%), thirteen lateral meniscus tear(28%), ten medial collateral ligament injury(28%), one PCL injury (2%) were associated with ACL injury. The twenty nine bone marrow changes were found in twenty patients {43%) which included acutely injured seven patients. In acute cases, the bone marrow changes were depicted as diffuse or focal high signal intensity lesions in lateral femoral or tibial condyles in contrast to the changes in chronic cases depicted as focal low signal intensity lesions in variable location. Lateral femoral condylar notch depression were found in nine patients(19%) and avulsion fractures of anterior tibial spine in four patients(9%). CONCLUSION: The associated findings with ACL injury (anterior translocation, buckling of PCL, associated bone, ligament and meniscus injuries) are considered to be helpful in the diagnosis of ACL injury on Knee MR images, when the findings of anterior cruciate ligament itself are not confirmative.

Avascular Necrosis of Femoral Head: Findings of Contrast-Enhanced MR Imaging

PURPOSE: To evaluate the findings and the role of contrast enhanced magnetic resonance imaging in avascular necrosis of femoral head. MATERIALS AND METHODS: Sixteen patients with avascular necrosis of femoral head were examined with MRI. Tl-weighted and T2-weighted images and contrast-enhanced Tl-weighted images were obtained. Enhancing characteristics of the necrotic area and synovium were determined. Also a change of the disease extent after enhancement was assessed. RESULTS: Twenty seven avascular necrosis of the femoral head including 11 cases of bilateral lesion were detected. Fifteen cases revealed collapse of the femoral head. The portions of the lesion with low signal intensity on Tl-weighted images and high signal intensity on T2-weighted images showed contrast enhancement in 15 cases. However, the portions with low signal intensities both on T1 and T2-weighted images showed enhancement in one case. There was no significant change of the disease extent after enhancement. Synovium showed enhancement in 18 cases, and joint effusion was detected in 23 cases. CONCLUSION: Contrast enhanced MR images may be helpful in predicting histopathologic findings of avascular necrosis of the femoral head, but not useful for evaluating the extent of disease.

MR Findings of Recurred Giant Cell Tumor

PURPOSE: To describe MR findings of recurred giant cell tumor of bone. MATERIALS AND METHODS: MR imagings of ten cases of pathologically proven recurrence of giant cell tumor were retrospectively analyzed. Location of recurrence, multiplicity of recurred tumor, signal intensity and homogeneity, pattern of gadolinium enhancement, soft tissue and articular surface involvement were evaluated. RESULTS: Tumors were located in peripheral portion of previous operation site(80%). Six cases recurred as multiple lesions. Tumor showed low signal intensity on T1 weighted images(100%), high signal intensity on T2 weighted images(100%) and inhomogeneous peripheral rim enhancing pattern(75%). Soft tissue and articular surface involvement were also demonstrated. CONCLUSION: We concluded that characteristic MR findings of recurred giant cell tumor could be helpful in early detection and precise evaluation of tumor recurrence.

Piezoelectric Extracorporeal Lithotripsy of Gallbladder Stones: New Inclusion Criteria

PURPOSE: To establish the optimal inclusion criteria for the patients with gallbladder stones to extracorporeal shock wave lithotripsy(ESWL) by retrospectively analyzing our current results. MATERIALS AND METHODS: Data obtained from 201 patients with gallbladder stones treated with ESWL and oral chemolytic agent from November 1989 to July 1992 were restroepectively analyzed. Ninety-six had radiolucent stones and 105 had radiopaque stones. We used piezoelectric lithotriptor(EDAP LT. 01) and there were no limitation in number of sessions or total number of shock waves. ESWL was repeated until the size of the largest fragment is smaller than 4 mm. Follow up ultrasound was done in every three months after the successful fragmentation. Average length of the follow up was 205 days. We analyzed the rate of successful fragmentation, number of shock waves needed to achieve successful fragmentation according to the size, number of stones as well as the presence of the calcification. Stone-free rate after 6 months was also calculated from all subgroups and compared to each other. RESULTS: The rate of successful fragmentation was 76.2% for radiolucent stones and 66.6% for radiopaque stones(p > 0.05) after 46,731 and 56,111 shock waves respectively(p > 0.05). The rate of successful fragmentation was highest in patients with single, radiolucent stone smaller than 2cm(91.7%) followed by single radiolucent stone larger than 2cm(83.3%), multiple calcified stones smaller than 2cm(77.4%) and single calcified stone smaller than 2cm(72.1%). The rate of complete stone clearance after 6 month follow-up was highest in patients with single radiolucent stone smaller than 2cm(63.3%) and followed by multiple calcified stones smaller than 2cm(37.3%), single calcified stone smaller than 2cm(33.9%)(p <0.05). CONCLUSION: To obtain better results with ESWL in patients with gallbladder stone, the authors propose a more strict inclusion criteria, which is the patient with a single, radiolucent stone smaller than 2cm.

MR Findings of Spondylolisthesis: Assessment of Associated Spinal and Neural Foraminal Stenosis

PURPOSE: To assess the spinal canal and neural foraminal stenosis associated with spondylolisthesis on MR imaging. MATERIALS AND METHODS: We retrospectively analysed MR findings of 63 cases of spondylolisthesis(degenerative type:23 cases, isthmic type:40 cases) regarding the type and grade of spondylolisthesis, prensence or absence of associated spinal canal stenosis, and the severity of associated neural foraminal stenosis. RESULTS: Central canal stenosis were more frequent in degenerative type(91%) than isthmic type(33%), and more frequent in grade II spondylolisthesis of degenerative type(100%) and isthmic type(89%) than in grade spondylolisthesis of degenerative type(45%) and isthmic type(20%). There was positive correlation between the severity of neural foraminal stenosis and the grade of spondylolisthesis, whereas there was no significant difference between degenerative and isthmic types. CONCLUSION: Degenerative spondylolisthesis were frequently associated with central canal stenosis more than isthmic type. When the grade of spondylolisthesis was higher, it was more frequently associated with central canal stenosis and severe neural foraminal stenosis.

An Experimental Study on the Role of Blood Vessels in the Formation of Peritumoral Abnormal MR Signal Intensity

PURPOSE: To assess the role of blood vessels in the formation of peritumoral abnormal signal intensity which exaggerates the size of malignant tumor on MR images. MATERIALS AND METHODS: We performed MR-microangiographic-pathologic correlation using implanted VX-2 carcinoma in 16 rabbit thighs 1-28 days after tumor implantation. The shape and distribution of abnormal vessels were analyzed on microangiography and on histologic examination in correlation with peritumoral abnormal signal intensity on MR images. RESULTS: Dilated peritumoral blood vessels gave rise to irregular, tortuous tumor vessels penetrated into the tumor. With the tumor growth, hypervascular tumor vessels in peritumoral area and central avascular areas were increased. These hypervascular areas on microangiography were corresponded with abnormal signal intensity on MR images. CONCLUSION: Hypervascularity could be a cause of peritumoral abnormal signal intensity which exaggerates the size of experimentally induced malignant musculoskeletal tumors on MR images.

Magnetic Resonance Imaging of Infarcted Liver Induced by Selective Ligation of Right Portal Vein in Rabbits

PURPOSE:To investigate the changes of abnormal signal intensity of liver infarction in scheduled intervals after ligation of portal vein in rabbit livers with histopathologic correlation. MATERIALS AND METHODS:Liver infarction were induced by selective ligation of the posterior branch of right portal vein in 12 rabbits. T1- and T2-weighted MRI at 2.0T with spin-echo techniques as well as contrastenhanced Tl-weighted MRI with Gd-DTPA(0.1 mmol/kg) were performed 3 hours, 6 hours, 1 day, 3 days, 1 week, and 2 weeks after ligation using two rabbits at each interval. Histopathologic specimens were prepared from six removed livers for comparing the MR findings with the histopathologic findings. The other six rabbits were sectioned transversely in frozen state for comparing MR findings with the macroscopic findings of pathologic areas of the liver. RESULTS: The signal intensity of pathologic hepatic segment showed more hyperintense signal than that of normal segments of the liver on TI-, proton density-, and T2-weighted MR images at every interval after ligation, except both T2WI of 3 hours interval and one T1WI of 2 weeks interval. Main histopathologic findings 3 hours, 6 hours, 1 day, 3 days, and 1 week after ligation were congestion, hemorrhage with necrosis, coagulation necrosis, complete necrosis, and necrosis with scar tissues, respectively. Microscopic specimens with Prussian blue stain 6 hours, and 1 week after ligation showed bluish hue indicating the existence of methemoglobin, and blue particles in giant cells and monocytes indicating engulfing hemosiderin, respectively. CONCLUSION: Changes of the signal intensities on sequential MR images of acutely induced hemorrhagic liver infarction might be due to the rapid oxidative denaturation of hemoglobin in hemorrhages and high signal intensity on Tl-weighted images from the hyperacute stage of a hemorrhagic liver infarction could be due to methemoglobin. Therefore, acutely induced hemorrhagic liver infarction should be included in the differential diagnoses of the hyperintense liver lesions on Tl-weighted images.

Detection of VX-2 Carcinoma in Rabbit Livers: Comparison of Sonography, CT, and IVIRI

PURPOSE: Our study was designed to investigate the value of different imaging techniques in the early detection of VX-2 carcinoma in rabbit livers by direct comparison of sonography, CT, and MR imaging with pathologic specimens. MATERIALS AND METHODS: VX-2 carcinomas were induced in 20 rabbit livers by direct inoculation of 0. 1ml of aliquot of the tumor tissue suspension (1 x 106/mm3) to hepatic parenchyma with an 18 gauge needle after laparotomy. One week after the inoculation of tumor cells, sonography with a 5 MHz transducer, CT after a bolus injection of contrast medium (3 mL/kg), and Tl-weighted MR imaging at a 2. 0T with spin-echo techniques (TR/TE:500/30 msec, 2000/30, 80 msec) as well as enhanced Tl-weighted MR imaging with GD-DTPA (0. 1 mmole/kg) were performed in each rabbit. RESULTS: At pathologic specimens, adequate induction of tumor nodules were 69 with 3--21 mm size (average 8. 3 mm). All 69 tumors had fibrous capsules and central necrosis pathologically. The sensitivities of sonography, contrast enhanced CT and MR imaging were 54%, 61%, and 87%, respectively. Among MR images, the sensitivities of Tl-weighted images, proton density images, T2-weighted images, and enhanced Tl-weighted images were 33%, 77%, 83%, and 81%, respectively. On sonograms and CT scans, VX-2 carcinomas show variable appearance regardless of the tumor size and histopathologic findings. On MR images, the tumors were ring shape with variable thickness on all pulse sequences. There was no significant correlation among the findings of three imaging techniques. CONCLUSION: MR imaging has the highest detectability for the VX-2 carcinomas in rabbit liver. Therefore, MRI may be the most valuable imaging technique for the detection of small hepatic tumors with extensive necrosis like VX-2 carcinomas.

MR Findings of Giant Cell Tumor: Signal Intensity and Morphological Characteristics

PURPOSE: To describe the MR characteristics of giant cell tumor of bone. MATERIALS AND METHODS: MR iraagings of 15 cases of pathologically proved giant cell tumor were retrospectively analyzed. Signal intensity and homogeneity, involvement of articular surface, low signal intensity rim around the tumor, cortical disruption and soft tissue involvement were evaluated. RESULTS:Tumor showed low signal intensity on T1 weighted images(93%), inhomogenous high signal on T2 or T2* weighted images(93%) and inhomogeneous enhancing pattern(88%). In 11 cases of giant cell tumor of long bones, all cases showed involvement of articular margin and 10 cases(90%) showed rim of low signal intensity between tumor and normal marrow. Disruption of cortical bone(25%) and soft tissue involevement(7%) were also demonstrated. CONCLUSION: We concluded that giant cell tumor showed characteristic MR findings could be helpful in making correct diagnosis.

MR Imaging of the Pigmented Villonodular Synovitis of the Knee

PURPOSE: To describe the magnetic resonance (MR) findings of pigmented villonodular synovitis(PVNS) of the knee, and to evaluate the clinical value of MR in the diagnosis of PVNS. MATERIALS AND METHODS:MR imagings of seven patients with PVNS were studied. The type of lesion, presence of bony erosion, the signal intensity, and the relationship between contrast enhancement and signal intensity on T2-weighted images were analyzed, retrospectively. RESULTS: The lesion was mainly villous in three patients and nodular in four, and bony erosion was seen in one patient. On T2-weighted image, the signal intensity of the villous form was mixed iso- and hypointense in two, hypointense in one, and that of the nodular form was heterogeneous with hypo-, iso-, and hyperintensities. The hypointense portion on T2-weighted image showed poor contrast enhancement, which may suggest hemosiderin deposition or advanced fibrosis. The iso- or hyperintense portion on T2-weighted image showed strong enhancement, which suggest active cellular proliferation. CONCLUSION:MR imaging could be a very useful modality in the diagnosis as well as prediction of histological findings of the PVNS.

MR Findings of Extraabdominal Desmold Tumors: Correlation with H istopathologic Findings

PURPOSE: To understand the MR findings of extraabdominal desmold tumors by correlation with histopathologic findings. MATERIALS AND METHODS: MR images of histologically proved 12 patients with extraabdominal desmold tumor were retrospectively reviewed. Three types of MR features were defined; type I had signal changes on T1 and T2 weighted images and relatively homogeneous nature, type II had homogeneously low signal intensities on T1 and T2 weighted images and type III was a mixed form of type I and type II. Signal intensity, enhancement pattern and margin of the lesions were analyzed on MR images. Pathologic features were analyzed by three aspects, which were cellularity, amount of collagen and vascularity, and were correlated with MR images. RESULTS: The signal intensities of type I desmolds were intermediate on T1 weighted image and higher on T2 weighted image with localized margin and gadolinium enhancement. Pathologically this type showed predominant cellularity and vascularity. The signal intensities of type II desmold were homogenous low signal intensities on both T1 and T2 weighted images without enhancement. Pathologically this type showed predominant collagen components and hypovascularity. Type III desmolds were mixed form of type I and type II on MR images as well as on pathologic features. Type I and type II desmold tumors had localized margins, however type III had both localized and infiltrative margins. CONCLUSION: The MR findings of extraabdominal desmold tumors would reflect the pathologic background of the tumor.

MR of vertebral compression fracture: Acute and chronic trauma versus metastasis: Emphasis on the signal intensity and enhancement

Magnetic resonance (MR) imaging was performed in 41 patients with compression fracture of the spine. MR images of 14 patients with acute spinal trauma (within recent 1 month), eight patients with chronic trauma (over 1 month), and 19 patients with malignant cause without history of trauma were analyzed, retrospectively. Low signal intencities on T1-weighted images and high signal intensities on T2-weighted images were noted in 86% (12/14) of patients with acute trauma, Iso-signal intensities on all pulse sequences were noted in 50%(4/8) of patients with chronic trauma. Low signal intensities on T1-weighted images and high signal intensities on T2-weighted images were noted in 100%(19/19) of patients with metastatic compression fracture. Contrast enhancement was observed in all the cases of acute trauma(4/4) and metastases(18/18), whereas only 20% (1/5) of chronic trauma showed enhancement. Fragmentation was seen in 35% (5/14) of patients with acute trauma, in 25%(2/8) with chronic trauma, and not seen in the patients with metastasis. In conclusion, acute traumatic compression fracture can not be differentiated from malignant cause by MR signal intensity or contrast enhancement, but chronic compression fracture can be distinguished from metasasis. Fragmentation may suggest traumatic compression fracture. So MRI could be a useful method in differentiating the benign compression fractures from the pathologic ones caused by malignancy.

Differentiation of amebic versus pyogenic liver abscess with US and CT

To differentiate amebic and pyogenic liver abscesses, sonography(US) and CT findings of 21 amebic and 22 pyogenic liver abscesses were reviewed retrospectively. US was performed in all cases and CT in 15 cases of each group. Eleven cases of amebic abscesses had well defined margin which was observed in 10 cases of pyogenic abscessed. Amebic abscesses showed hyperechoic wall in 7 cases and calcification in 4 cases. Ten cases of pyogenic abscesses had mearby intrahepatic duct dilatation which was observed in 2 cases of amebic abscesses. Pneumobilia was seen in 6 cases of pyogenic abscesses. US findings of clear margin and hyperechoic wall, and CT findings of intrahepatic duct dilatation, pneumobilia, and calcification were helpful in differentation of amebic pyogenic liver abscesses.

Pyogenic osteomyelitis of long bone: MR findings

To evaluate the usefulness of MR in the osteomyelitis, we reviewed MR examinations of 14 patients with pyogenic osteomyelitis of the long bone. All 14 patients were confirmed to have osteomyelitis either surgically (13/14) or by aspiration (1/14). MRI was performed with 0.5R (n=8) or 2.0T (n=6) SE technique, and Gd-DTPA enhanced T1WI was obtained in 10 examinations. Anatomic location of lesions were femur (8/14), tibia (5/14),m and fibula (1/14). The marrow cavity and soft tissue were involved in 13/14, 12/14 respectively. The signals of both intraosseous and extraosseous infected area were iso to low signal intensity to muscles on T1WI and high signal intensity on PDWI & T2WI. Rim or diffuse enhancement of the marrow cavity and soft tissue were seen in all (10/10) cases. Sequestra, periosteal reaction. And cortical defect were found in 12/14, 10/14, 9/14. MR provided more accurate and detailed anatomic information including extent of disease and possible activity than bone scintigraphy, CT, or conventional radiography. We conclude that MR might be the choice of modality in the diagnosis of osteomyelitis of the long bone.

Radiologic findings of osteochondritis dissecans

To evaluate the radiographic characteristics of osteochondritis dissecans (OCD) and useful parameter for predicting mechanical stability, we retrospectively analysed 26 plain radiographic examinations and seven MR imagings in 28 cases of OCD in 24 patients. Typical radiologic findings were osteochondral defect with sclerotic rim of variable thickeness and osteochondral fragment. Sites of osteochondral defect were medial (35.9%) or lateral (32%) femoral chondyle and medial (7.1%) or lateral (25%) side of talar dome. Sclerotic rim was seen in 24 cases (85%) and osteochondral fragments including nine loose bodies were seen in 21 cases (75%). The size of osteochondral defect with unstable fragment (average 2.05cm) and loose body (2.04cm) in the knee joint were similar to, but statistically larger than that with stable fragment (1.35cm). All osteochondral defects were well visualized on MR images. Abnormalities of articular cartilage and effusion in the interface between the parent bone and fragment were seem in five cases of which there were confirmed three unstable cases arthroscopically. We conclude that size of defect may be a good parameter for predicting mechanical stability and MRI may be useful in the diagnosis of OCD and determining the methods of treatment.

Magnetic resonance imaging of rabbit kidney after renal vein ligation

This study was designed to evaluate the potential applicability of magnetic resonance imaging (MRI) for the diagnosis of acute renal vein thrombosis. Renal vein thrombosis was experimentally induced by surgical ligation of the left renal vein in a total of 21 rabbits. MRI was performed with a 0.5 Tesla superconductive magnetic system. Spin echo technique was used with varying TR and TE parameters. Spin echo images of the rabbit kidney were analysed for morphology and signal intensity. T1 and T2 relaxation times of the renal cortex and medulla were calculated from the images. After venous ligation, kidneys became enlarged. Low signal band along the outer medulla in T2 weighted images were characteristically shown from 1 hour to 3 days after ligation, Changes of cortex to medullar contrast (CMC) values were significant (p<0.05) in T1 - and T2- weighted images of the ligated side. T1 and T2 relaxation times were significantly prolonged (p<0.05) on the ligated side, both in the cortex and medulla from 1 hour to 2 weeks after the ligation, while T2 relaxation time on the contralateral side was significantly prolonged both in the cortex and medulla 2 weeks after venous ligation. The most useful MRI criteria for the diagnosis of renal vein thrombosis were enlarged renal size, and the low signal band along the outer medulla of ligated kidney. The relative intensity difference between cortex and medulla (CMC) in T1-and T2-weighted images, and T1 and T2 relaxation times were suggested to be the useful MR parameters for the diagnosis of acute renal vein thrombosis.

Magnetic resonance imaging of rabbit kidney after renal vein ligation

This study was designed to evaluate the potential applicability of magnetic resonance imaging (MRI) for the diagnosis of acute renal vein thrombosis. Renal vein thrombosis was experimentally induced by surgical ligation of the left renal vein in a total of 21 rabbits. MRI was performed with a 0.5 Tesla superconductive magnetic system. Spin echo technique was used with varying TR and TE parameters. Spin echo images of the rabbit kidney were analysed for morphology and signal intensity. T1 and T2 relaxation times of the renal cortex and medulla were calculated from the images. After venous ligation, kidneys became enlarged. Low signal band along the outer medulla in T2 weighted images were characteristically shown from 1 hour to 3 days after ligation, Changes of cortex to medullar contrast (CMC) values were significant (p<0.05) in T1 - and T2- weighted images of the ligated side. T1 and T2 relaxation times were significantly prolonged (p<0.05) on the ligated side, both in the cortex and medulla from 1 hour to 2 weeks after the ligation, while T2 relaxation time on the contralateral side was significantly prolonged both in the cortex and medulla 2 weeks after venous ligation. The most useful MRI criteria for the diagnosis of renal vein thrombosis were enlarged renal size, and the low signal band along the outer medulla of ligated kidney. The relative intensity difference between cortex and medulla (CMC) in T1-and T2-weighted images, and T1 and T2 relaxation times were suggested to be the useful MR parameters for the diagnosis of acute renal vein thrombosis.