Role of MRI in the diagnosis of insufficiency fractures of the sacrum and acetabular roof

OBJECTIVE: To review the risk factors and the radiological appearance of insufficiency fractures of the sacrum and acetabular roof. DESIGN AND PATIENTS: Twenty patients with sacral and acetabular roof insufficiency fractures were reviewed retrospectively. There were 16 women (80%) and 4 males (age range 48-86 years, excluding an 8-year-old boy). Thirteen patients had a known tumour, and nine had received pelvic irradiation. All patients, except one who was asymptomatic, presented with low back or hip pain. In patients with a known tumor, metastases were suspected. Plain radiography (20), bone scintigrams (16), MR examinations (20), and bone densitometry (14) were performed. Nine patients also each had a CT scan. RESULTS AND CONCLUSIONS: In three cases the CT scan performed 10-25 days after onset of symptoms was interpreted as normal. MR examination performed a few days after the CT scan showed in each of these three patients a fracture line with a band of edema. Scintigraphy was very sensitive, but the H-shaped pattern of sacral uptake, specific for an insufficiency fracture, was detected in only three of 16 cases. The earliest MR sign was medullary edema, seen as early as 18 days after the onset of symptoms. On spin echo (SE) T1-weighted images (T1WI), the hypointense signal of edema could mask a fracture line. On SE T2WI the fracture line could be detected within the hyperintense edema (10 of 17 patients with examinations including SE T2WI). However, in four patients a fracture of the sacrum was not seen on T2WI, these having been obtained in the axial plane. For this reason, intravenous gadolinium was injected, revealing a fracture line in 12 of 14 examinations, or fat suppression sequences were performed, revealing a fracture line in five of five cases. The total number of fractures detected was 17 [15 fractures of the sacrum (bilateral in 10 cases) and two of the acetabular roof]. At a later stage, the edema resolved and the fracture was clearly seen. The two cases of fracture of the acetabular roof were easily recognized at MRI, particularly in the sagittal plane.     

Fetal intracranial hemorrhage. Imaging by ultrasound and magnetic resonance imaging

OBJECTIVE: To describe the magnetic resonance imaging (MRI) findings associated with fetal intracranial hemorrhage and to compare them with ultrasound findings. STUDY DESIGN: In four pregnancies complicated by fetal intracranial hemorrhage, fetal imaging was carried out using T2-weighted fast spin echo sequences and T1-weighted fast low angle shot imaging sequences and by transabdominal ultrasonography. RESULTS: An antepartum diagnosis of hemorrhage was made by ultrasound in one case and by MRI in two. Retrospectively, the hemorrhagic area could be identified from the MRI images in an additional two cases and from the ultrasound images in one case. In the cases of intraventricular hemorrhage, the MRI signal intensity in the T1-weighted images was increased in the hemorrhagic area as compared to the contralateral ventricle and brain parenchyma. In a case with subdural hemorrhage, T2-weighted MRI signals from the hemorrhagic area changed from low-to high-intensity signals during four weeks of follow-up. Better imaging of the intracranial anatomy was possible by MRI than by transabdominal ultrasonography. CONCLUSION: MRI can be used for imaging and dating fetal intracranial hemorrhages. Variable ultrasound and MRI findings are associated with this complication, depending on the age and location of the hemorrhage.     

Antimyosin scintigraphy compared with magnetic resonance imaging in inflammatory myopathies

OBJECTIVE: To compare indium In 111 altumomab pentetate-labeled antimyosin scintigraphy with magnetic resonance imaging (MRI) in the diagnosis and follow-up of patients with myositis. DESIGN AND METHODS: Sixteen patients with polymyositis and 1 patient with dermatomyositis, all verified with biopsy samples, were examined during diagnostic evaluation with antimyosin antibody scintigraphy and low-field MRI of the thighs and calves using T1- and T2-weighted sequences. Both examinations were repeated 6 to 22 months after therapeutic intervention with antiinflammatory drugs. The performance of the 2 methods for the assessment of the severity of muscle inflammation was evaluated using comparison with clinical examination and the serum creatine kinase level. RESULTS: At diagnosis all patients had increased uptake of antimyosin antibody in the thighs and/or calves. In T2-weighted MRI images, increased signal intensity changes reflecting intramuscular edema and inflammation were seen in all patients in at least 1 muscle group in the thighs or calves. After anti-inflammatory drug therapy, the mean uptake of antibody and the mean signal intensity changes in T2-weighted MRI had decreased. However, in T1-weighted MRI the signal intensity changes reflecting intramuscular fatty degeneration were more pronounced in the follow-up study. The level of serum creatine kinase had decreased markedly by the second examination except in 1 patient who also had more accumulation of antibody in the calves after than before treatment. The clinical condition improved in 8 patients and remained unchanged in 9 patients. CONCLUSIONS: Antimyosin scintigraphy and T2-weighted MRI are feasible tools for the detection and follow-up of lesions in patients with myositis. Scintigraphy findings correlate with serum creatine kinase activity and seem to reflect disease activity better than T2-weighted MRI changes, whereas secondary degenerative intramuscular lesions are only detectable using T1-weighted MRI.     

Diagnostic and surgical management of spinal dural arteriovenous fistulas

OBJECTIVE: A retrospective review was conducted to compare magnetic resonance (MR) and conventional spinal angiographic images and to investigate the outcome of our treatment protocol for patients with spinal dural arteriovenous fistulas (DAVFs). MATERIALS AND METHODS: Nine patients with a diagnosis of DAVF based on clinical myelopathy and preoperative MR imaging (MRI) and MR angiography (MRA) findings were treated at our institution by the senior author (BAG). All nine patients initially presented with progressive myelopathy. Preoperative MRI revealed T2-weighted signal abnormalities in all patients, and MRA was diagnostic in all patients. Each patient underwent a laminectomy and ligation of the arterialized draining vein. Selective spinal angiograms were used to confirm the level of fistula immediately before the surgical procedure was performed and to document complete obliteration after clip ligation of the medullary draining vein. Follow-up MRI and MRA were performed approximately 2 months postoperatively. RESULTS: MRI T2-weighted signal hyperintensity improved after surgery in all nine patients. Postoperatively, progression of motor weakness and gait difficulty was halted and some improvement was observed in all patients. No patient was neurologically normal, however. To date, there has been no clinical or MRA evidence of recurrence in any patient. CONCLUSION: Preoperative MRA and intraoperative spinal x-ray angiography present as an effective combination for diagnosing and intraoperatively confirming DAVF. Both T1-weighted enhancement and T2-weighted signal hyperintensity on MR images improved after the obliteration of the DAVFs and correlated with clinical improvement in all nine patients. MRA provides adequate visualization and localization of spinal DAVFs and may serve as a useful noninvasive tool for diagnosing and following patients with spinal DAVFs in the future.     

Injury of the posterior ligament complex in patients with acute spinal trauma: evaluation by MR imaging

OBJECTIVE: We undertook this study to use MR imaging to determine the frequency of injury to the posterior ligament complex of the thoracolumbar spine in patients who have undergone acute thoracolumbar trauma. SUBJECTS AND METHODS: Sixty-eight patients with varying severity of thoracolumbar trauma were examined prospectively. The majority of injuries were related to motor vehicle accidents. The second most common cause was falls. Patients were examined with plain radiography and MR imaging. In addition to conventional MR imaging sequences consisting of T1-weighted and fast spin-echo T2-weighted sagittal and axial images, a fat-suppressed T2-weighted sagittal sequence was performed. The findings were correlated with surgery in six cases and with follow-up clinical examination that included physical examination and conventional anteroposterior and lateral radiographs. RESULTS: Posterior ligament complex injury was detected in 53% (n = 36) of all patients. Such injury was most common in patients with flexion-distraction (n = 15) and patients with dislocation fracture (n = 4). Of the patients with dislocation fracture, all had posterior ligament complex injury. Of the 24 patients with burst fractures, posterior ligament complex tear occurred in 42% (n = 10). Of the 23 patients with compression fractures, 26% (n = 6) had posterior ligament complex tear. Injury to the interspinous ligaments occurred with decreasing frequency in patients with injury to the supraspinous ligament, flaval ligaments, posterior longitudinal ligament, and anterior longitudinal ligament. Surgical findings correlated with MR imaging in all six patients who underwent surgery. CONCLUSION: Injury to the posterior ligament complex, which is often encountered in patients with burst and compression fractures, can be reliably revealed by MR imaging.     

Renal cell carcinoma: preoperative assessment for enucleative surgery with angiography, CT, and MRI

PURPOSE: Our purpose was to assess various imaging methods in detecting a pseudocapsule of renal cell carcinoma (RCC), which is critical for successful tumor enucleation. METHOD: In 42 patients with histopathologically proven RCC, images obtained at angiography (n = 42), CT (n = 30), and MRI (n = 19) were investigated retrospectively. All patients underwent treatment (enucleation: n = 15; nephrectomy: n = 27). The imaging criteria for the presence of a pseudocapsule were as follows: a surrounding radiolucent rim on angiography, a low or high density rim on CT, and a low intensity rim on MRI. All images were retrospectively reviewed by three radiologists without knowledge of the clinical and histological findings. RESULTS: Thirty-three of 42 RCCs showed a pseudocapsule on the surgical specimen. A pseudocapsule was detected in 67% of tumors (22/33) on angiography, 26% (6/23) on CT, 27% (4/15) on T1-weighted MRI, 93% (14/15) on T2-weighted MRI, 67% (8/12) on dynamic enhanced T1-weighted MRI, and 15% (2/13) on delayed enhanced T1-weighted MRI. CONCLUSION: T2-weighted MR images are superior for visualizing a pseudocapsule of RCC and for providing reliable selection criteria for tumor enucleation.     

Stromal invasion by carcinoma of the cervix: assessment with dynamic MR imaging

OBJECTIVE: The purpose of this study was to evaluate dynamic MR imaging in assessing the depth of stromal invasion by carcinoma of the cervix and to compare dynamic MR imaging with T2-weighted and contrast-enhanced T1-weighted MR imaging. SUBJECTS AND METHODS: Forty-one patients with carcinoma that was clinically considered to be confined to the cervix were examined with T2-weighted, dynamic, and contrast-enhanced T1-weighted MR imaging before surgery. We evaluated enhancement patterns of the cervix and tumor and assessed the degree of stromal invasion with MR imaging. The degree of stromal invasion was divided into two groups: superficial disease (no stromal invasion or invasion of < or = 3 mm) and deep invasion (> 3 mm of stromal invasion). Then we compared these MR findings with histologic results for the depth of stromal invasion. RESULTS: With dynamic MR imaging, cervical carcinoma with deep invasion was seen as a focal enhanced area in the early dynamic phase. The cervical epithelium and stroma enhanced less vividly. In distinguishing deep invasion from superficial disease, we found the accuracy of T2-weighted MR images, dynamic MR images, and contrast-enhanced T1-weighted MR images to be 76%, 98%, and 63%, respectively. In particular, the detectability of 3.1-5.0 mm of stromal invasion with dynamic MR images was significantly higher than that with the other techniques: with T2-weighted MR images, we saw 3.1-5.0 mm of stromal invasion in 23% of patients; with dynamic MR images, in 92%; and with contrast-enhanced T1-weighted MR images, in none. Superficial disease was not revealed with any of the three MR techniques. CONCLUSION: We believe that dynamic MR imaging is superior to T2-weighted MR imaging and contrast-enhanced T1-weighted MR imaging when assessing the depth of invasion of cervical carcinoma.     

Low-field magnetic resonance imaging (0.2 T) of tendons with sonographic and histologic correlation. Cadaveric study

RATIONALE AND OBJECTIVES: The authors evaluate the role of low-field strength magnetic resonance imaging (MRI) compared with sonography in the evaluation of degenerative changes of tendons, with histologic correlation, based on investigations of horse cadavers. METHODS: Low-field MRI and sonography was performed in 42 hours specimens for the evaluation of tendons and ligaments. Magnetic resonance imaging included sagittal and axial T1-weighted, T2-weighted, and gradient echo images. Sonography and MR images were evaluated for degenerative changes or tears and the findings were correlated with the histologic results. RESULTS: Using histologic findings as a gold standard, the accuracy for the sonographic evaluation was 65.9%, sensitivity was 16.7%, and specificity was 100%. The corresponding data for low-field MR imaging were 70.5% accuracy, 44.4% sensitivity, and 88.5% specificity. CONCLUSIONS: Low-field MRI investigation allows more accurate staging of tendinous changes than sonography. It is more reproducible and potentially includes the advantages of the combined evaluation of bones, ligaments, and soft tissue.     

Role of magnetic resonance imaging in renal transplant recipients with acquired cystic kidney disease

OBJECTIVES: To evaluate the impact of magnetic resonance imaging (MRI) in renal transplant recipients whose ultrasound (US) examinations of the native kidneys have met the criteria of acquired cystic kidney disease (ACKD). METHODS: The US scans of 840 renal allograft recipients were prospectively studied. In addition, 46 of 169 patients diagnosed with ACKD by US scans underwent MR examination. MRI protocols included (a) T1 and T2-weighted fast spin echo imaging, (b) T2-weighted gradient echo imaging, and (c) gadolinium-enhanced T1-weighted imaging in 7 patients with evidence of complex cysts. In the case of complex lesions, both US and MRI follow-up examinations were performed between 6 and 12 months after the prior examination. RESULTS: US examination showed ACKD in 169 of 840 patients. In addition, US revealed 8 patients with renal cell carcinomas (RCC). Of these 8 patients, 7 had evidence of ACKD. The median number of cysts depicted on US examination in native kidneys of renal transplant recipients was 3 (range 0 to 10) on both sides. MRI revealed significantly more and smaller cysts compared to US. The median number of cysts was seven on the left and nine on the right native kidneys, respectively. MRI revealed 18 complex lesions in 7 patients. Thirteen of 18 complex lesions were undetected by US. CONCLUSIONS: MRI is superior to US in depiction of simple and complex lesions of native kidneys in renal allograft recipients. MRI exhibits no overestimation of the prevalence of ACKD on the basis of the US criteria already mentioned. Advantages of MRI do not justify routine screening tests by this imaging modality. However, MRI should be used for further evaluation of complex lesions detected by US.     

Projections of the ventral tegmental area of the midbrain, the substantia nigra, and the amygdaloid body in different parts of the putamen in the dog

INTRODUCTION: We investigated the accuracy of endorectal coil Magnetic Resonance Imaging (MRI) and Fast Spin Echo (FSE) technique in staging prostate cancer. MATERIAL AND METHODS: MRI was performed in 70 patients with biopsy proved prostatic cancer. A total of 33 patients subsequently underwent radical prostatectomy. T2-weighted FSE sequences (TR 3400-4100, TE 120, Echo train length 13) were acquired in all patients. Axial, sagittal and coronal 4-5 mm images were obtained with 13-14 cm field of view and 256 x 256 matrix. Additional T1-weighted spin echo images were acquired in 9 patients. Lesion staging on MR images was performed according to the American Urological System. MR data were compared with the pathologic findings of whole-mount sections of the surgical specimens. RESULTS: Overall accuracy for endorectal coil MR imaging was 60%; ten cases were underestimated and 3 cases were overestimated. The sensitivity and the specificity of endorectal coil MRI in diagnosing capsular penetration were 77% and 81%, respectively. Seminal vesicle invasion was detected with 87% sensitivity and 96% specificity. CONCLUSIONS: Endorectal coil MRI provides a more accurate preoperative local staging.     

Only visual impressions are almost always present in long-term memories, and reported completeness, accuracy, and verbalizability of recollections increase with age

PURPOSE: To stage advanced cervical carcinoma with conventional or pharmacokinetic magnetic resonance (MR) imaging by correlating imaging findings with whole-mount specimens and histopathologic findings. MATERIALS AND METHODS: Twenty-six adult patients with primary cervical cancer (stages IIB-IVA) underwent T2-weighted turbo spin-echo (SE) MR imaging; gadolinium-enhanced, T1-weighted SE MR imaging; and gadolinium-enhanced, saturation-recovery, turbo fast low-angle shot MR imaging. All imaging findings were correlated with the whole-mount specimens and histopathologic findings. Signal intensity changes versus time were analyzed by using a pharmacokinetic model and parameter values displayed as a color-coded overlay. RESULTS: Histopathologic stages were IIB (n = 9), IIIB (n = 1), and IVA (n = 16). The overall accuracy for tumor staging was 73% for T2-weighted, 81% for T1-weighted, and 92% for pharmacokinetic MR imaging. Pharmacokinetic MR imaging was accurate (90%) in the diagnosis of tumor extension into the bladder and/or rectal wall but inaccurate (69%) in that of parametrial invasion. T2-weighted images were most accurate (86%) in the assessment of parametrial tumor extension but less accurate (69%) in that of bladder or rectal invasion. CONCLUSION: T2-weighted turbo SE images are still superior to contract medium-enhanced T1-weighted SE or pharmacokinetic MR images in the diagnosis of parametrial infiltration by uterine cervical carcinoma. However, pharmacokinetic MR imaging is a promising method for demonstrating and staging IVA disease.     

Hepatocellular carcinoma: CT and MR features after transcatheter arterial embolization and percutaneous ethanol injection

PURPOSE: To investigate the reliability of computed tomography (CT) and magnetic resonance (MR) imaging in the evaluation of the response of hepatocellular carcinoma (HCC) to transcatheter arterial embolization (TAE) followed by percutaneous ethanol injection (PEI). MATERIAL AND METHODS: Between January 1991 and November 1992, 20 patients (15 men and five women, aged 53-73 years [mean, 64.6 years]) with 31 HCC lesions underwent CT and MR imaging before and after treatment with combined TAE and PEI. RESULTS: Twenty-seven tumors, which were hypointense on post-treatment T2-weighted images and on gadolinium-enhanced T1-weighted images, were seen to be necrotic at biopsy. In four cases of incomplete necrosis, viable tumor was hyperintense on T2-weighted images and was enhanced after administration of contrast material. CT provided a larger spectrum of imaging features as a result of the presence of both hyperattenuating areas (caused by retention of iodized oil) and hypoattenuating areas (due to ethanol-induced necrosis). CONCLUSION: CT and MR imaging findings proved useful in the evaluation of the response of HCC to combined TAE and PEI.     

Preoperative staging of endometrial carcinoma: diagnostic effect of T2-weighted fast spin-echo MR imaging

PURPOSE: To evaluate the usefulness of T2-weighted fast spin-echo magnetic resonance (MR) imaging with a 512 x 256 matrix for assessment of the preoperative stage of endometrial carcinoma. MATERIALS AND METHODS: Twenty-eight women with histopathologically proved endometrial carcinoma underwent preoperative T2-weighted fast spin-echo, dynamic T1-weighted fast spin-echo, and postcontrast T1-weighted spin-echo MR imaging with a phased-array surface coil. The uterine long-axis planes in each sequence were reviewed at separate sessions by three radiologists blinded to the histopathologic data. RESULTS: For the diagnosis of myometrial invasion, no statistically significant differences were found among T2-weighted imaging, dynamic imaging, and postcontrast T1-weighted imaging. For the diagnosis of deep myometrial invasion, T2-weighted and dynamic images showed higher specificity than postcontrast T1-weighted images (T2-weighted, 89%; dynamic, 88%; and postcontrast T1-weighted, 80%). For cervical invasion, T2-weighted and dynamic images showed larger areas under receiver operating characteristic curves than did postcontrast T1-weighted images (T2-weighted, 0.78; dynamic, 0.71; and postcontrast T1-weighted, 0.67). CONCLUSION: T2-weighted imaging is useful for identifying the stage of endometrial carcinoma.     

Gadolinium-enhanced MR imaging of temporomandibular disorders: improved lesion detection of the posterior disk attachment on T1-weighted images obtained with fat suppression

OBJECTIVE: The purpose of this study was to assess the potential for improved lesion detection in the posterior disk attachment and its surrounding tissue in temporomandibular disorders when gadolinium-enhanced MR imaging performed with fat suppression is used. MATERIALS AND METHODS: Forty-five patients underwent MR imaging with conventional T1- and T2-weighted, gadolinium-enhanced T1-weighted, and gadolinium-enhanced fat-suppressed spin-echo imaging sequences. Qualitative and quantitative assessments of the contrast enhancement of each type of imaging were also performed. RESULTS: The contrast-enhanced fat-suppressed T1-weighted imaging sequence had several advantages over the other imaging techniques in detecting abnormalities of the posterior disk attachment and in detecting bone marrow lesions in the mandibular condyle. The most significant advantage was better enhancement of lesion conspicuity. The diagnostic accuracy of contrast-enhanced fat-suppressed imaging was 77% versus 70% for conventional contrast-enhanced imaging. The kappa value for interobserver agreement was .95 for contrast-enhanced fat-suppressed imaging and .72 for conventional contrast-enhanced imaging. CONCLUSION: Contrast-enhanced fat-suppressed T1-weighted spin-echo MR imaging is a valuable technique for visualizing the extent and degree of lesions in the posterior disk attachment and bone marrow lesions in the mandibular condyle.     

MR tomography of acute pancreatitis: initial results

Magnetic resonance imaging (MRI) was evaluated for its potential in assessment of acute pancreatitis compared to computed tomography (CT). 15 patients with acute pancreatitis were examined using a routine protocol including T1- and T2-weighted sequences and a fat-suppressed T1-weighted spin-echo sequence. Gadopentant-Dimeglumin (Gd-DTPA) was given. For comparison, plain and contrast-enhanced CT was performed prior to MRI. MRI proved to be superior to CT in detection of bleeding, duodenitis and ascites. MRI failed to detect concrements. These first results show that, considering the latest development in technology, MRI is not inferior to CT in diagnostic imaging of acute pancreatitis.     

Cerebral amyloid angiopathy: prospects for clinical diagnosis and treatment

The MRI features of small renal cell carcinomas (RCCs) were retrospectively reviewed and correlated with histology in 24 patients. MRI features on both T1- and T2-weighted images were classified into hypointensity, isointensity, and hyperintensity. Each tumor was pathologically classified into four types: alveolar, papillary, tubular, and cystic. These findings were correlated with MR signal intensities. Alveolar tumors showed hypointensity to isointensity on T1-weighted image and isointensity to hyperintensity on T2-weighted image. In contrast, all papillary tumors showed hypointensity on T2-weighted image. Four of six tumors with hypointensity on T2-weighted image were caused by hemosiderin deposition, hemorrhage, and necrosis. However, there were two papillary RCCs that showed hypointensity on T2-weighted image despite no hemosiderin deposition and no hemorrhage. We conclude that papillary RCC is associated with T2-hypointense appearance as well as hemosiderin deposition, hemorrhage, and necrosis.     

Detection of hepatic tumors: arterial-phase MR imaging versus spiral CT arteriography

BACKGROUND: Distinction between uncomplicated infective fasciitis and early necrotizing fasciitis can be extremely difficult without operation, yet the management and prognosis of both conditions depend greatly on early recognition and assessment of the extent of involvement. STUDY DESIGN: This was a prospective review of the utility of magnetic resonance imaging (MRI) in nine patients with suspected infective or necrotizing fasciitis treated at an academic medical center or a Veterans Administration hospital. RESULTS: Magnetic resonance imaging documented fascial inflammation, characterized by low intensity on T1-weighted images and high intensity on T2-weighted images, in all nine patients. Absence of gadolinium contrast enhancement on T1-weighted images reliably detected fascial necrosis in all six patients who required operative debridement. Magnetic resonance imaging was extremely useful in defining the extent of fasciitis and was more accurate in predicting necrosis or pyomyositis than was myoglobinuria or elevation of serum creatine kinase or lactate dehydrogenase. Operation was avoided in two patients without evidence of necrosis on MRI. One patient without evidence of necrosis, explored because of contradictory clinical findings, was confirmed at operation to have cellulitis without necrosis. CONCLUSIONS: Magnetic resonance imaging with gadolinium contrast accurately determines the presence of necrosis and the need for operation in patients with fasciitis of the lower extremity. Preoperative determination of the extent of involvement facilitates operative planning.     

High signal intensity of globus pallidus on T1-weighted MRI in liver cirrhosis patients: clinical and pathological study

In some patients with liver cirrhosis, the globus pallidus shows high signal intensity on T1-weighted MRI. The relationship was examined between high signal intensity on T1-weighted images and pathological conditions such as liver function, portal venous pressure and metal concentrations in brain. The signal of the globus pallidus on T1-weighted imaging became highly enhanced in accordance with prolongation of prothrombin time, deterioration of ICG R15, or decrease in choline esterase and the Fisher ratio. Furthermore, the high signal intensity was also seen in patients with high portal pressure and large varices. In histopathological study, remarkable atrophy and loss of nerve cells were observed in globus pallidus with high signal intensity on T1-weighted imaging, changes that were similar to those in with patients with manganese poisoning. The manganese concentration in autopsied globus pallidus with high signal intensity on T1-weighted imaging showed a 9.5-fold increase compared with that with normal intensity. In conclusion, the deposition of manganese in the globus pallidus, which is accompanied with the nerve cell deciduation, brings about the high signal intensity of the globus pallidus on T1-weighted MRI in patients with liver cirrhosis.     

Red degeneration of uterine leiomyoma: MR appearance

OBJECTIVE: Red degeneration (hemorrhagic infarction) of uterine leiomyoma can cause acute abdominal pain. This study was undertaken to identify MR features useful in diagnosing this rare complication of uterine leiomyoma. MATERIALS AND METHODS: Magnetic resonance imaging from five patients symptomatic for 7 to 20 days with pathologic confirmation of red degeneration was retrospectively evaluated and correlated with histopathologic findings. RESULTS: The lesions had a common MRI appearance: hyperintense rim on T1-weighted imaging (WI) and hypointense rim on T2-WI. These findings corresponded with numerous dilated vessels filled with red blood cells at the periphery of the lesion. The signal characteristics of the rim are best explained as an effect of abundant intracellular methemoglobin in these vessels. CONCLUSION: Recognition of these characteristics may help radiologists differentiate symptomatic red degeneration from other clinical conditions that need surgical interventions.