Glomangiopericytoma of the Spinal Cord

Glomangiopericytoma, also referred to as a hemangiopericytoma-like tumor or sinonasal type hemangiopericytoma, is a rare tumor of the nasal cavity and paranasal sinus that has never been reported in the spinal cord. Here, we report a case of a 47-year-old man who developed glomangiopericytoma in the thoracic spine. This lesion showed a heterogeneous high signal intensity compared to the spinal cord on a T2-weighted image and an easily enhanced isointense signal on a T1-weighted image.

Diagnostic Value of MRI in Schwannoma / 대한골관절종양학회지

PURPOSE: To diagnose soft tissue tumor, such as lipoma and Schwannoma, magnetic resonance imaging (MRI) is sufficient in most cases. However, various characteristics are found in MRI images of Schwannoma, thus other type of tumors are often misdiagnosed as Schwannoma with MRI images. In this study, we evaluate the diagnostic value of specific MRI findings of Schwannoma. MATERIALS AND METHODS: From January 2002 to May 2013, 104 patients who are suspected as Schwannoma rith MRI images are included in data, and the final diagnosis is confirmed with biopsy. Patients are divided into group 1 and group 2 who are confirmed as Schwannoma and other disease with biopsy, respectively. RESULTS: 92 patients were diagnosed as Schwannoma (group 1) and 12 patients were diagnosed as other disease (group 2). We investigate the diagnostic value of specific MRI findings of Schwannoma. 41 patients of group 1 (45%) and 0 patients of group 2 (0%) showed target sign, 47 patients of group 1 (51%) and 2 patients of group 2 (17%) showed fascicular sign, 44 patients of group 1 (48%) and 5 patients of group 2 (42%) showed fat split sign, 28 patients of group 1 (30%) and 1 patients of group 2(9%) showed nerve entering and exiting sign, and 8 patients of group 1 (9%) and 6 patients of group 2 (50%) showed none of four specific findings on their MRI images. 52 patients of group 1 (57%) and 5 patients of group 2 (42%) have tumors on the pathway of nerve. Target sign could be considered as the best diagnostic value of the sign we investigate (p<0.05). CONCLUSION: Although specific MRI findings have powerful diagnostic value, patients are often misdiagnosed as Schwannoma with MRI findings. Therefore, if patients who are suspected as Schwannoma based on MRI findings have no target sign on their MRI images, we should consider the possibility of other disease.

Intramuscular Sparganosis in the Gastrocnemius Muscle: A Case Report

Sparganosis is a parasitic infection caused by the plerocercoid tapeworm larva of the genus Spirometra. Although the destination of the larva is often a tissue or muscle in the chest, abdominal wall, extremities, eyes, brain, urinary tract, spinal canal, and scrotum, intramuscular sparganosis is uncommon and therefore is difficult to distinguish from a soft tissue tumor. We report a case of intramuscular sparganosis involving the gastrocnemius muscle in an elderly patient who was diagnosed using ultrasonography and MRI and treated by surgical excision. At approximately 1 cm near the schwannoma at the right distal sciatic nerve, several spargana worms were detected and removed.

Baker's Cyst with Intramuscular Extension into Vastus Medialis Muscle

Baker's cysts are one of the most common cystic lesions around the knee joint and mainly caused by fluid distension of the gastrocnemius-semimembranous bursa that is situated along the medial side of the popliteal fossa. Typically, a Baker's cyst extends along the intermuscular planes around the knee joint and may enlarge any direction. However, it is mostly located in the inferomedial or superficial layers of the knee joint and less commonly extends laterally or proximally. Expansion of the cyst tends to respect the intermuscular planes, and Baker's cysts along the intramuscular route have been rarely reported. Thus, we report a case of Baker's cyst with intramuscular extension into the vastus medialis muscle.

Functional and Radiological Results of Intermediate-term Follow Up in MUTARS(R) Tumor Endoprostheses / 대한골관절종양학회지

PURPOSE: This study was designed to verify intermediate-term functional and radiological results of limb salvage operation using endoprosthetic replacement system (MUTARS(R)) used in patients with a malignant bone tumor. MATERIALS AND METHODS: Thirty one cases which used MUTARS(R) tumor prosthesis were reviewed. The mean age of the patients was 49.2 years and the mean follow up was 39.8 months. We retrospectively reviewed complications, and evaluated functionally and radiologically by Enneking functional score, ISOLS radiological implants evaluation system at last follow-up. RESULTS: 3 patients had died of disease, distant metastasis was seen in 4 patients and local recurrence was seen in 1 patients. Complications were developed in 12 patients. (infection 6, leg length discrepancy 2, aseptic loosening 2, periprosthetic femoral fracture 1, screw loosening 1) Mean value of total functional scores were 81.2% in proximal femur, 77.4% in distal femur, 78.1% in proximal tibia, and 80.2% in proximal humerus. The overall radiological result was relatively satisfactory. CONCLUSION: Our results suggest limb salvage with the MUTARS(R) endoprosthesis is successful with good functional and radiological results. But we should be careful with complications such as infection.

The Value of 18-FDG PET CT in Soft Tissue Sarcoma / 대한정형외과학회잡지

PURPOSE: Recently, there have been many attempts to use PET-CT for the diagnosis of metastasis of soft tissue tumors and for differentiating benign tumors from malignant tumors. In this study, we wanted to evaluate the efficacy of 18-FDG PET CT in soft tissue tumors. MATERIALS AND METHODS: Patients (n=64) with suspected malignant soft tissue tumor had 18-FDG PET CT scans. This included 15 cases of benign soft tissue tumor, 34 cases of malignant soft tissue tumor and 15 cases of inflammatory lesions. All patients went through surgical treatment after PET-CT imaging was done, and all dissected tissues were biopsied. For semiquantitive analysis, SUVmax(Maximal standard uptake value) was measured, and SUVmax was determined using ROC analysis, the Kruskal-Wallis test and the Mann-Whitney test. RESULTS: Using 18-FDG PET CT it was possible to differentiate benign from malignant tumor using SUVmax values. But, discrimination between different grades of tumor was not possible. Also discrimination between malignant tumors and inflammatory lesions was not possible. CONCLUSION: PET-CT can be considered as a useful nuclear imaging method that can detect local recurrence and distant metastasis of soft tissue sarcoma and can differentiate benign from malignant tumors. But PET-CT results must be interpreted carefully in diagnoses when there is inflammatory disease or a suspected lesion present.

Array-comparative Genomic Hybridization Analysis of Alveolar Soft Part Sarcoma

BACKGROUND: Alveolar soft part sarcomas (ASPSs) are rare, histologically distinctive soft tissue sarcomas of unknown origin. Although ASPSs are characterized by a specific alteration, der(17)t(X;17)(p11;q25), the entire spectrum of genetic events underlying the pathogenesis of ASPS is unclear. Using array-based comparative genomic hybridization (array-CGH), we examined the DNA copy number changes in ASPS. METHODS: Array-CGH, composed of 4,030 clones, was performed in two samples of fresh frozen tumor tissues from a 29-year-old male and a 16-year-old female. RESULTS: We identified 16 commonly altered chromosomal regions involving 25 genes. Eleven altered regions were located on chromosome Xp (Xp22.33, Xp22.11, Xp11.3, Xp11.3-Xp11.23, Xp22.2, Xp22.12, Xp22.31, Xp22.32, Xp21.1, Xp21.3, and Xp11.4). Additional regions with an increased copy number were observed at 1q25.1, 7q35, 12p12.1, and 17p11.2. Loss was found in only one region of chromosome 22q11.23. Several genes located within the amplified region of Xp included GYG2, ARSD, ARSE, ARSH, UBE1, USP11, PCTK1, ARAF, SYN1, TIMP1, XK, PDK3, PCYT1B, PHEX, ARX, RPS6KA3, TMSB4X, TMEM27, BMX, and KAL1. CONCLUSIONS: This was the first application report of genome-wide copy number changes by BAC array-CGH in ASPSs. Our study showed unique genomic regions and new candidate genes that suggest a neural origin and are associated with tumor pathogenesis in ASPSs.

MR Histoanatomical Distribution of 290 Soft-tissue Tumors

PURPOSE: This study was designed too identify the MR histoanatomical distribution of soft-tissue tumors. MATERIALS AND METHODS: A total of 290 soft-tissue tumors of 281 patients were analyzed by the use of MR imaging and were pathologically confirmed after surgical resection or a biopsy. There were 120 malignant soft-tissue tumors including tumors of an intermediate malignancy and 170 benign tumors. The histoanatomical locations were divided into three types: 'Type I' with superficial layer tumors that involved the cutaneous and subcutaneous tissue, 'Type II' with deep layer tumors that involved the muscle or tendon and 'Type III' with soft-tissue tumors that involved both the superficial and deep layers. RESULTS: Soft-tissue tumors with more than three cases with a frequency of more than 75% included dermatofibrosarcoma protuberans, glomus tumor, angiolipoma, leiomyosarcoma and lymphoma as 'Type I' tumors. 'Type II' tumors with more than three cases with a frequency of more than 75% included liposarcoma, fibromatosis, papillary endothelial hyperplasia and rhabdomyosarcoma. 'Type III' tumors with more than three cases with a frequency of more than 50% included neurofibromatosis. CONCLUSION: The MR histoanatomical distributions of soft tissue tumors are useful in the differential pathological diagnosis when a soft-tissue tumor has a nonspecific MR appearance.

MRI Evaluation for the Histologic Components of Soft-tissue Tumors: Comparison of MEDIC and Fast SE T2-weighted Imaging

PURPOSE: To compare Multi Echo Data Image Combination (MEDIC) and fast SE T2- weighted images with fat saturation (T2FS) to suggest more accurate evaluation of the histologic components of soft-tissue tumors. MATERIALS AND METHODS: The experimental group included 25 histologic tissues (5 vascular, 4 neural, 4 fibrous, 4 hypercellular, 2 hemorrhagic necroses, 2 cystic, 2 lipoid, 1 myxoid stroma, and 1 thrombus) in 10 patients who had pathologically confirmed schwannoma (n = 3), hemangioma (n = 2), lipoma (n = 1), angiokeratoma (n = 1), synovial sarcoma (n = 1), liposarcoma (n = 1), and malignant fibrous histiocytoma (n = 1). The inhomogeneity values were measured using the standard deviation value (SD) divided by the mean value as SD presents an error amount similar to that of imaging heterogeneity. RESULTS: The inhomogeneity values of 25 histologic components were lower on MEDIC than those on T2FS (p < .001). CONCLUSION: We conclude that MEDIC is more accurate than T2FS for evaluating the tissue components of soft-tissue tumors using digitalized data because MEDIC images have far lower inhomogeneity.

Marrow Conversion Pattern of the Femora and Acetabulum Around Hip Joints According to Age Group : MR Evaluation

PURPOSE : Marrow edema and fatty degeneration of the hip joint bones could be initial and late signs inip joint and its bone diseases respectively, which might be differentiated from age-related marrow conversion pattern. So authors have investigated normal marrow conversion pattern of the femur and acetabulum around the hip joints. MATERIALS AND METHODS : Three coronal MR images of 288 hip joint bones in 144 subjects, aged 2 days to 76 years divided to 8 groups every 10 years, were retrospectively analysed for the location and appearance of the converted yellow marrow. The converted yellow marrow were divided to head, neck, and trochanter in the proximal femur and below and above 50% in acetabulum of the hip. RESULTS : The most common type of marrow conversion is the converted yellow marrow in the entire proximal femur and below 50% of acetabulum of the hip. We observed the start of marrow conversion in just before and after 2 years old and stopped at just before and after 20 years old. CONCLUSION : The understanding of age-related marrow conversion pattern of the hip joint bones would provide some information for differentiation from pathologic condition of them such as edema, fatty degeneration, metastasis, or leukemia.

Endovascular Treatment of a Ruptured Internal Mammary Artery Pseudoaneurysm Presenting as Massive Hemothorax in a Patient with Type I Neurofibromatosis

We report a case of an acute hemothorax caused by a rupture of a left internal mammary artery pseudoaneurysm in a 45-year-old woman with a type I neurofibromatosis, which was successfully treated using endovascular coil embolization.

Effectiveness of Intra-arterially Administered Abciximab as a Rescue Method for Intracranial Acute In-Stent Thrombosis

PURPOSE: To determine the efficacy and safety of the intra-arterial administration of glycoprotein IIb/IIIa inhibitor for resolving acute in-stent thrombosis complicating stent-assisted angioplasty for intracranial atherosclerosis. MATERIALS AND METHODS: We placed 60 therapeutic stents (24 internal carotid arteries, 20 vertebrobasilar arteries, and 16 middle cerebral arteries) for the treatment of symptomatic intracranial atherosclerosis. Among the 60 stenting procedures, acute in-stent thrombosis occurred after stent deployment in 11 cases (18.3%). As the method of dissolving the acute in-stent thrombosis, 2 mg abciximab were intra-arterially administered through a guiding catheter. Angiography was then performed after 10-20 minutes to identify any undissolved material resulting from the thrombosis. If the thrombosis was still observed on the angiography, an additional 2 mg of abciximab were administered, and this procedure was repeated until complete thrombolysis was obtained. Post-procedural non-enhanced brain CT was performed for the evaluation of possible hemorrhagic complications. RESULTS:After each intra-arterial administration of 2 mg of abciximab, successive angiographies showed the process of resolution of the acute thrombosis. All 11 acute in-stent thromboses were completely dissolved within 40 to 80 minutes. The total dosage of infused abciximab was 8 mg in one case, 10 mg in eight cases, and 16 mg in two cases. Post-procedural non-enhanced brain CT revealed no hemorrhagic complications. CONCLUSION: The intra-arterial administration of abciximab can be a safe and effective therapeutic method for acute in-stent thrombosis complicating the stenting of stenotic intracranial arteries.

Usefulness of Multiplanar Reformatted Images of Multi-detector Row Helical CT in Assessment of Biliary Stent Patency

PURPOSE: To evaluate the usefulness of multi-detector row helical CT (MDCT), multiplanar reformatted images for the noninvasive assessment of biliary stent patency, and for the planning for management in patients with a self-expandable metallic stent due to malignant biliary obstruction. MATERIALS AND METHODS: Among 90 consecutive patients, from August 1999 to July 2003, 26 cases in 23 patients with malignant biliary obstruction who underwent self-expandable metallic stent insertion in the biliary system and percutaneous transhepatic biliary drainage within 7 days after CT were enrolled in this study. On CT images, the complete and functional obstruction of the stent and the precise level of obstruction were evaluated. The presence of an enhancing intraluminal mass or wall thickening around stent was determined, and the causes of obstruction were evaluated. These findings were then compared with percutaneous transhepatic cholangiography. RESULTS: Multi-detector row helical CT correctly demonstrated the patency of a stent in 24 cases (92.3%). It was adequate in helping to depict the precise level of stent occlusion in 23 cases (88.5%). Multi-detector row helical CT also revealed the extent of tumor that represented as an enhancing intraluminal mass or wall thickening around the stent in 23 cases, and this was represented as complete obstruction on percutaneous transhepatic cholangiography. In the case of functional obstruction, MDCT predicted the possible cause of the obstruction. CONCLUSION: Multiplanar reformatted images of multi-detector row helical CT is a useful imaging modality for the noninvasive assessement of stent patency and the precise level of obstruction when stent obstrution is suspected in the patients with self-expandable metallic stent due to malignant biliary obstruction. It can also predict the possible cause of the obstruction and allows adequate planning for the medical management of such cases.

The Usefulness of Multiplanar Reconstruction Images in Preoperative T-staging of Advanced Gastric Cancer

PURPOSE: The purpose of this study was to evaluate the performance of multidetector-row CT (MDCT) in the preoperative T-staging of patients with advanced gastric cancer. MATERIALS AND METHODS: A total of 65 patients with an established diagnosis of advanced gastric cancer (T2 or more) were evaluated with MDCT. The protocol of MDCT consisted of high-quality (HQ) mode helical scanning with a slice thickness of 2.5 mm. The axial CT images were reconstructed with a slice thickness of 5 mm. MPR images were reconstructed from the raw axial data with a slice thickness of 5 mm. A comparison between the standard axial and axial MPR images was performed by two radiologists with regard to the evaluation of the tumor location and T-stage. These findings were compared with the pathologic and surgical findings. RESULTS: T-staging of the advanced stomach cancer was correct in 89% (58/65) and 69% (45/65) of the MPR images and axial images, respectively. The MPR images improved the detection rate (5 lesions)of the tumors and increased the accuracy of the T-staging (13 lesions) in comparison with the axial images. The MPR images are of greater diagnostic value for the evaluation of omental seeding (5 lesions: axial images, 9 lesions: MPR images), tumor location and extension. CONCLUSION: Multiplanar reconstruction (MPR) images provide increased confidence in the location and T-staging of certain cases of advanced gastric cancer, such as those in locations where CT images are susceptible to be affected by the difficulties associated with partial volume averaging. In this study, the MPR images provided more precise information about the tumor location and T-staging than the standard axial images in the preoperative evaluation of advanced gastric cancer.

Dynamic Images for Prediction of Therapeutic Efficacy of Hepatocellular Carcinoma Treated with Transcatheter Oily Chemoembolization

PURPOSE: To predict the therapeutic efficacy of transcatheter oily chemoembolization(TOCE) in the treatment. MATERIALS AND METHODS: We reviewed the findings of 24 dynamic CT or MR scans examined for the purpose of diagnosis before TOCE, and follow-up CT scans obtained after this procedure. In 24 patients (M:F=20:4) with a mean age of 52.2 years, 43 nodular HCCs with a diameter of 5 cm or less were present. The patients underwent double dynamic CT or MR imaging as one arterial phase 30 seconds after the intravenous injection of contrast media, and this was followed by a delayed phase 5 minutes fter injection. HCCs were then classified as one of four types: Type I, high and low attenuation or intensity during the arterial and delayed phase, respectively; Type II, iso- and low; Type III, iso- and high; and Type IV, high and iso-. In addition, we classified the degree of lipiodol accumulation by HCC nodules as either Grade 5 (fullmoon-like lipiodolization), Grade 2 (about 40%), or Grade 1 (about 20%), as seen on follow-up CT scans after TOCE. RESULTS: Type I provided an accuracy of 72.1% considering to more than 50% lipiodol accumulation. However, a single finding demonstrating high atenuation or intensity during the arterial phase gave an accuracy of 79.1% better than that of Type I. CONCLUSION: A finding of high attenuation or intensity during the arterial phase, as seen on dynamic CT or MR images, provides the best information about the therapeutic efficacy of HCCs treated by means of with TOCE.

Evaluation of Critical Function in Pathologic Solitary Kidneys Using 99mTc-DMSA Scintigram / 대한신장학회잡지

OBJECTIVE: To make decision of the dialysis or transplantation in the patient with renal failure should be demanded the precise measurement serving the critical level of the renal function. 99mTc- DMSA is a new renal scanning agent that provides a good quality of renal image as a result of preferential cortical accumulation and also makes feasible a quantitative assessment of renal function. We want to know the critical level of the renal function with 99mTc-DMSA scanning in the experimental rabbits with pathologic solitary kidney. MATERIALS AND METHODS: We made artificial left hydronephrosis having left ureter ligation at 2 weeks after performing right functional nephrectomy with vessels ligation in 20 experimental rabbits. At 24, 48, and 72 hours after then, 99mTc-DMSA renal uptake rates, serum urea nitrogen, and creatinine were checked to evaluate the critical levels of renal function impairment. RESULTS: Before left ureteral ligation 99mTc- DMSA renal uptake rates, serum urea nitrogen, and creatinine were 9.59+/-1.14%(mean+/-SD), 28.0+/-5.2 mg/dl, and 1.3+/-0.2 mg/dl respectively. Those of the fifteen pathologic solitary kidney at 24 hours after ureter ligation were 4.37+/-1.68%, 74.2+/-20.2mg/dl, and 7.6+/-2.4mg/dl respectively. Those of the thirteen at 48 hours were 4.25+/-1.09%, 126.0+/-33.5mg/dl, and 9.8+/-3.5mg/dl respectively. And serum urea nitrogen and creatinine of the twelve at 72 hours were 183.9+/-51.0mg/dl, and 14.4+/-2.3mg/dl respectively. 99mTc- DMSA renal uptake rates appeared indiscriminate values with approaching to death while the levels of serum urea nitrogen and creatinine revealed increasing values. CONCLUSION: 99mTc-DMSA renal scan was one of the appropriate tests to evaluate the critical level of renal function impairment.

Stress Fracture in Posterior Aspect of the Tibia

PURPOSE: To determine correlation between stress fracture of the posterior tibia and flexor digitorum longusmuscle injury caused by athletic or sporting activity during adolescence. MATERIALS AND METHODS: Eleven casesdiagnosed as stress fracture after X-ray and MR imaging of the lower leg were reviewed. With regard to eachfracture, the following features were noted: age, sex, and athletic or sporting activity of the patient, and site.Using MR imaging techniques, axial and sagittal T1 and T2 weighted images were obtained in all cases and T1-GdDTPA images in seven. RESULTS: The activities undertaken were running (n=3), football (n=2), ballet (n=2),taekwando (n=1), badminton (n=1), field hockey (n=1), and basketball (n=1). MR images revealed localized corticalthickness (n=11), linear intramedullary callus showing a low signal on T1 and T2 weighted images (n=9), marrowhyperemia (n=7), and flexor digitorum longus muscle injury showing a high signal on T1-Gd DTPA and T2 weightedimage (n=7). CONCLUSION: Stress fracture of the posterior tibia might be induced by flexor digitorum longusmuscle activity induced by athletic or sporting activities during adoleseence.

Renal Damage induced by Doxorubicin-Lipiodol Emulsion infused into Rabbit Renal Artery: Comparison with CT andHistologic Findings

PURPOSE: The purpose of this study was to evaluate the utility of renal CT scanning and to histologicallycorrelate renal damage induced by renal arterial infusion of 0.2 ml/kg of doxorubicin-lipiodol emulsion. MATERIALS AND METHODS: Renal CT scans of 20 rabbit kidneys were obtained 15 days after transcatheter arterialchemoembolization and were classified into four grades, as follows : Grade 0 - no fleck, Grade 1 - one to threenodular flecks ; Grade 2 - four or more nodular flecks, or one semilunar fleck ; and Grade 3 - two or moresemilunar flecks. The percentage of histological section occupied by lesion was determined using squared paper,and compared with the grades determined on the basis of CT. RESULTS: The histologic findings were interstitialinflammatory cell infiltration, intratubular lipiodol droplets, dystrophic calcification, and cellular necrosis.The mean sizes of grade 0, 1, 2 and 3 histological lesions were 2.2%(n=5), 4.5%(n=4), 21.9%(n=7), and 24%(n=4),respectively. Grades 0 and 1 accounted for nine cases(3.2%), while grades 2 and 3 accounted for 11(22.6%) ; thisdifference was statistically significant(p<0.01). CONCLUSION: CT findings showing nodular or semilunar flecks 15days after infusion into the renal artery of doxorubicin-lipiodol emulsion correlate with the size of the damagedkidney, as seen on histological specimens.

Survival Rates in Hepatocellular Carcinoma Patient Treated by Transarterial Chemoembolization: Comparison withOperable and Inoperable Cases

PURPOSE: To pr6edict the prognosis of hepatocellular carcinoma (HCC) patients who underwent transarte6rialchemoembolization(TACE). MATERIALS AND METHODS: The study unvestigated the one- and two-year survival rates of 211patients who were divided into two groups : 74 operable Child's grade A or B cases, and 137 inoperable casesinvolving Child's grade C or poor prognostic factors such as metastasis, main portal thrombus, and total bilirubinabove 2.0mg/dl. Cumulative survival curves were obtained by the Kaplan-Meier method, beginning with the day of thefirst TACE. RESULTS: The one- and two-year cummulative survival rates were 80.8% and 47.9% for the 74 operablecases and 37.6% and 14.0% for the 137 inoperable cases, respectively(P<0.01). CONCLUSION: The prognosis of HCCpatients who underwent TACE can be predicted by classifying then into two groups, operable or inoperable cases.

MR Imaging Findings of Renal Infarction Induced by Renal Artery Ligation in Rabbits: The Usefulness of Diffusion-weighted Imaging

PURPOSE: To assess the usefulness of diffusion-weighted imaging(DWI) in evaluating serial parenchymal changesin renal infarction induced by renal artery ligation, by comparing this with the conventional spin echo techniqueand correlating the results with the histopathological findings. MATERIALS AND METHODS: In 22 rabbits, renalinfarction was induced by ligation of the renal artery. Spin-echo T1-weighted imaging(T1WI), turbo spin-echo(TSE)T2-weighted imaging(T2WI), and DWI were performed, using a 1.5-T superconductive unit, at 30 minutes, 1 hour, 2,3, 6, 12 and 24 hours, and 2, 3, 7 and 20 days after left renal artery ligation. Changes in signal intensity onT1WI, T2WI, and DWI were correlated with histopathologic findings. RESULTS: On MR images obtained 30 minutesafter ligation, the signal intensity of affected kidney was not significantly different from that of contralateralkidney, as seen on T1WI and T2WI, but was noticeably higher on DWI. On T2WI, the signal intensity ratio(SIR) wasslightly higher over time from 30 minutes to 2 days after ligation, and then decreased slightly. The SIR on DWIincreased abruptly at 30 minutes, remained high until 12 hours, and then fell, returning to close to the normalrange at between 2 and 3 days. It fell further, below the normal range, until 20 days after ligation. The mainhistopathologic findings after ligation were congestion and swelling of renal tubules (1-6 hours after ligation),degeneration and necrosis of renal tubules (12 hours - 2 days), coagulation necrosis of renal tubules(3 days),collection of cellular debris between renal tubules (7 days), and proliferation of fibroblast between renaltubules (20 days). CONCLUSION: Diffusion-weighted imaging is useful for the detection of hyperacute renalinfarction, and the apparent diffusion coefficient may provide additional information concerning its evolution.