Optimal carotid artery coverage for carotid plaque CT-imaging in predicting ischemic stroke.

OBJECTIVE: To determine the optimal spatial coverage for CT-imaging of carotid atherosclerosis, allowing the most accurate prediction of the associated risk of ischemic stroke. METHODS: In a cross-sectional study, we retrospectively identified 136 consecutive patients admitted to our emergency department with suspected stroke who underwent a CT-angiogram (CTA) of the cervical and intracranial carotid arteries. CTA studies of the carotid arteries were processed using a custom, CT-based automated computer classifier algorithm that quantitatively assesses a battery of carotid CT features. We used this algorithm to individually analyze different lengths of the common and internal carotid arteries for carotid wall features previously shown to be significantly associated with the risk of stroke. Acute stroke patients were categorized into "acute carotid stroke patients" and "non-acute carotid stroke patients" independently of carotid wall CT features. Univariate and multivariate analyses were used to compare the different spatial coverages in terms of their ability to distinguish between the carotid stroke patients and the noncarotid stroke patients using a receiver-operating characteristic curve (ROC) approach. RESULTS: The carotid wall volume was excellent at distinguishing between carotid stroke patients and noncarotid stroke patients, especially for coverages 20mm or less. The number and location of lipid clusters had a good discrimination power, mainly for coverages 15mm or greater. Measurement of minimal fibrous cap thickness was most associated with carotid stroke when assessed using intermediate coverages. Typically, a 20mm coverage on each side of the carotid bifurcation offered the optimal compromise between the individual carotid features. CONCLUSION: We recommend assessment of 20mm of each side of the carotid bifurcation to best characterize carotid atherosclerotic disease and the associated risk of ischemic stroke.

Differentiation between malignant and benign pathologic fractures with F-18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography.

OBJECTIVE: To evaluate the efficacy of F-18-fluoro-2-deoxy-D: -glucose positron emission tomography/computed tomography (FDG PET/CT) in differentiating malignant from benign pathologic fractures. MATERIALS AND METHODS: F-18 FDG PET/CT was performed on 34 patients with pathologic fractures between May 2004 and June 2007. Fractures were located in tubular bones (26), in the pelvis (six), in the spine (one) and in a rib (one). The FDG uptake pattern at the fracture site was described, whether FDG uptake occurred in the marrow or cortex and soft tissue. Maximum standardized uptake values (SUVmax, the largest value at the region of interest) were measured at the fracture site, including cortical bone, bone marrow and soft tissue. As a reference standard, biopsy was used for 12 patients and clinical follow-up for 22 patients. Sensitivity, specificity and diagnostic accuracy of PET/CT were calculated. RESULTS: There were 19 malignant and 15 benign fractures. In the malignant fractures, PET/CT demonstrated high (mean SUVmax 12.0, range 4.3 to 45.7) F-18 FDG uptake in bone marrow in most cases (17 of 19). In benign fractures, there was low FDG uptake (mean SUVmax 2.9, range 0.6 to 5.5) within cortical bone or adjacent soft tissue around the fracture, rarely in the marrow. There were significant differences in the pattern of intramedullary FDG uptake (P < 0.001) and in the mean SUVmax (P < 0.01) between malignant and benign fractures. The sensitivity, specificity and diagnostic accuracy of F-18 FDG PET/CT were 89.5%, 86.7% and 88.2%, respectively, with a cut-off SUVmax set at 4.7. The time interval between fracture and PET/CT did not significantly influence FDG uptake at the fracture site. CONCLUSION: F-18 FDG PET/CT reliably differentiated between malignant and benign fractures based on the SUVmax and based on medullary uptake, which was characteristic for malignant fractures.

Non-traumatic peroneal nerve palsy: MRI findings.

AIM: To present magnetic resonance imaging (MRI) findings of non-traumatic peroneal nerve palsy and to evaluate the usefulness of MRI in patients with non-traumatic peroneal nerve palsy. MATERIALS AND METHODS: In a retrospective study, 11 consecutive patients presenting with peroneal nerve palsy were included. MR images of the lower leg and electrophysiological examinations were also reviewed. The cause of peroneal nerve palsy was determined on the basis of MRI findings and was evaluated using electrophysiological data. Nine patients with causative lesions detected on MRI, underwent surgery. RESULTS: Clinical examination and electromyography (EMG) disclosed 11 peroneal lesions. MRI and EMG revealed three types of signal intensity change, i.e. deep peroneal nerve palsy type, common peroneal nerve palsy type, and superficial peroneal nerve palsy type. The MRI and EMG findings were in agreement in seven (65%) of the 11 study patients. In nine patients the causative lesions were identified using MRI, including ganglion cyst (n=6), osteochondroma (n=1), synovial cyst (n=1), and aneurysm (n=1). CONCLUSION: Ganglion cyst is the most common cause of non-traumatic peroneal nerve palsy. MRI offers a noninvasive method for obtaining useful information to assess, localize, and monitor peripheral peroneal nerve palsy.

Entrapment of the acetabular labrum following reduction of traumatic hip dislocation in a child.

In traumatic hip dislocation, concentric reduction can be prevented by various causes. Soft-tissue interposition, such as entrapment of the acetabular labrum, is a rare but important cause of failed reduction of a hip. Early diagnosis of incomplete reduction due to interposition of soft tissue is important, because delayed treatment is associated with a greater incidence of avascular necrosis of the femoral head and early onset of osteoarthritis. This report describes a case of acetabular labral entrapment following reduction of traumatic hip dislocation in a child. The importance of CT and MRI in arriving at an early diagnosis is emphasized.

Sonographic evaluation of gallbladder-wall thickening in hemorrhagic fever with renal syndrome: prediction of disease severity.

PURPOSE: Gallbladder-wall thickening (GBWT) frequently occurs in patients with hemorrhagic fever with renal syndrome (HFRS), an acute infectious disease caused by hantaviruses. HFRS is manifested by fever, hemorrhage, renal failure, and in many cases gastrointestinal symptoms, such as abdominal pain and tenderness. The clinical significance of GBWT in HFRS has not been reported. The purpose of this study was to investigate the incidence of GBWT and the relationship between GBWT and the severity of HFRS. METHODS: We retrospectively reviewed the medical records and sonograms of 68 patients with HFRS (47 males and 21 females, with an age range of 10-76 years) who underwent abdominal sonography in the acute stage of the disease. We measured the gallbladder-wall thickness on the sonograms and reviewed other sonographic and radiographic findings. Clinical factors that reflect the severity of HFRS were compared between the patients with GBWT (defined as thickness of 4 mm or more) and those without GBWT. RESULTS: Of the 68 patients, 29 (43%) had GBWT, which was even and diffuse in all cases. The patients with GBWT had a significantly lower mean platelet count and serum albumin level and significantly higher serum aspartate aminotransferase and serum lactate dehydrogenase levels than did the patients without GBWT. In addition, the incidence of renal failure requiring hemodialysis and the incidences of ascites and pleural effusion were higher in the patients with GBWT than in those without GBWT. Five patients died of HFRS; all 5 had GBWT (p = 0.011 for comparison with patients without GBWT). CONCLUSIONS: Our results suggest that the sonographic measurement of gallbladder-wall thickness during the acute stage of HFRS is useful for determining the severity of HFRS.

Access blood flow as a predictor of early failures of native arteriovenous fistulas in hemodialysis patients.

Blood flow imaging using color doppler has proven effective in predicting graft failures in hemodialysis patients, but its effect on native arteriovenous fistulas (AVF) is not well known. This study was performed to investigate whether measurements of the access blood flow can be used as predictors of an early failure of a native AVF in hemodialysis patients. Fifty-three consecutive patients who received native AVF operations were included in this study. Access blood flow was measured at 1 week after operations, and AVF function was followed for 4 months. During the follow-up, access failures developed in 10 patients at 9.8 +/- 3.5 weeks. AVF blood flow was significantly lower in the failure group (n = 10) than in the patent group (n = 43) (450 +/- 214 vs. 814 +/- 348 ml/min, p = 0.003). The incidence of access failures was higher in the patients with a flow <350 ml/min (n = 9) compared to the patients with a flow >350 ml/min (n = 44) (55.5 vs. 11.3%, p = 0.008). The diameters of veins were significantly smaller in the failure group than in the patent group (3.5 +/- 0.5 vs. 4.1 +/- 0.7 mm, p = 0.018). The incidence of diabetes mellitus was higher in the failure group than in the patent group (90 vs. 51%, p = 0.025). However, age, sex, duration from an operation to first cannulation, and different AVF sites did not make a significant difference between the two groups. Our data suggest that access blood flow measurements using color doppler ultrasound during early postoperative periods are useful parameters in predicting an early failure of a native AVF in hemodialysis patients.

Comparison of Tc-99m sestamibi and TI-201 uptake in multiple myeloma.

The authors report abnormal Tc-99m sestamibi (MIBI) and TI-201 uptake in a 62-year-old patient with histologically and biochemically proved myeloma. TI-201 imaging was undertaken for tumor evaluation, and 3 days later a Tc-99m MIBI study showed diffuse and focal marrow uptake with focal skull lesions, whereas TI-201 did not show skull lesions. After treatment, follow-up Tc-99m MIBI whole-body imaging was performed and the marrow uptake was decreased.

MR findings in ovarian granulocytic sarcoma.

Granulocytic sarcoma (chloroma) is a mass of malignant myeloid precursor cells in an extramedullary location. The female genital tract, including the ovary, may be the first site for clinical manifestation of granulocytic sarcoma. The MR findings are reported in a case of ovarian granulocytic sarcoma which preceded acute myelogenous leukaemia. Granulocytic sarcoma shows a mixed cystic and solid adnexal mass with intermediate signal intensity on T1 weighted images and hypointensity on T2 weighted images.

CT features of systemic lupus erythematosus in patients with acute abdominal pain: emphasis on ischemic bowel disease.

PURPOSE: To evaluate the computed tomographic (CT) features of systemic lupus erythematosus (SLE) in patients with acute abdominal pain. Special emphasis was placed on the analysis of ischemic bowel disease. MATERIALS AND METHODS: The authors retrospectively reviewed the images from 39 abdominal CT examinations performed in 33 patients with SLE and acute abdominal pain. Images were evaluated for bowel wall changes, mesenteric changes, fluid collection, retroperitoneal lymphadenopathy, peritoneal enhancement, and hepatomegaly as well as for changes in other abdominal organs. Ischemic bowel disease was diagnosed if at least three of the following signs were seen: bowel wall thickening, target sign, dilatation of intestinal segments, engorgement of mesenteric vessels, and increased attenuation of mesenteric fat. RESULTS: Thirty-one (79%) of the 39 examinations had CT findings diagnostic of ischemic bowel disease, including symmetric bowel wall thickening (n = 29), target sign (n = 26), and mesenteric vascular engorgement and haziness (n = 31). In 24 cases, bowel wall thickening was multifocal, with variable length, and did not appear to be confined to a single vascular territory. CONCLUSION: The most common CT finding in patients with SLE and acute abdominal pain is ischemic bowel disease. CT is useful for detecting the primary cause of gastrointestinal symptoms, planning treatment, and monitoring for infarction or perforation.

Intramedullary fat necrosis of multiple bones associated with pancreatitis.

We describe findings of intramedullary fat necrosis on five imaging studies in a patient with alcoholic pancreatitis. Radiography and CT of extremities showed multiple osteolytic lesions that were initially considered to be metastases. However, a 99mTc-methylene diphosphonate whole-body bone scan revealed abnormal areas of increased uptake in only the bones of extremities without involvement of the axial skeleton, a distribution quite unusual for metastatic disease. Furthermore, 99mTc-sestamibi scintigraphy was essentially normal. MRI revealed findings compatible with the diagnosis of fat necrosis/infarct. Findings from bone biopsy demonstrated necrotic bone marrow without malignant cells. It may not be necessary to perform all the imaging studies described in this report when clinical features suggesting metastatic fat necrosis are present. Appearance and distribution of abnormalities on the whole-body bone scan and MR images show that necrosis/infarct of the marrow may obviate bone biopsy, which is often needed to confirm the diagnosis of intramedullary fat necrosis and to exclude neoplastic processes.

Gastrointestinal leiomyoma and leiomyosarcoma: CT differentiation.

PURPOSE: Our goal was to evaluate CT efficacy in differentiating gastrointestinal leiomyoma and leiomyosarcoma. METHOD: We retrospectively reviewed CT scans of 45 patients (21 men, 24 women, mean age 55 years) with surgically proven gastrointestinal leiomyomas (n = 21) and leiomyosarcomas (n = 24) with respect to size, contour, enhancing pattern, mesenteric fat infiltration, calcification, ulceration, regional lymphadenopathy, direct invasion, distant metastasis, and growth pattern after visual inspection by two radiologists in agreement. On the basis of these CT features, subjective diagnosis was also categorized into three groups (Group I: probably benign, Group II: probably malignant, Group III: diagnostic malignant). The results were compared with the final histopathologic diagnosis. RESULTS: In addition to the features of direct invasion and distant metastasis suggesting diagnostic malignancy, the CT features favoring malignancy with statistical significance included larger size (> 5 cm), lobulated contour, heterogeneous enhancement, mesenteric fat infiltration, ulceration, regional lymphadenopathy, and exophytic growth pattern (p < 0.005). However, calcification was not significant in differentiating the two entities (p = 0.25163). A subjective analysis revealed 89% sensitivity, 85% specificity, and 87% accuracy for diagnosis of leiomyosarcoma. CONCLUSION: CT features are useful in differentiating leiomyoma and leiomyosarcoma in gastrointestinal tract.

Sarcomatous transformation of neurofibromas. Comparative imaging with Ga-67, Tl-201, Tc-99m pentavalent DMSA and Tc-99m MIBI.

A 29-year-old man, with a history of von Recklinghausen's disease, presented with progressive dyspnea associated with a rapidly growing mass on the right chest wall. Plain radiograph and CT of the chest revealed a huge soft-tissue mass with central low-density area involving the right upper lung and chest wall. SPECT imaging with Ga-67 citrate, Tl-201 chloride, Tc-99m pentavalent DMSA (V-DMSA), and Tc-99m MIBI were performed to characterize the mass. The tumor concentrated Ga-67, Tl-201, and Tc-99m (V) DMSA, but not Tc-99m MIBI. Punch biopsy of the lesion revealed malignant transformation of a thoracic neuroma (neurofibrosarcoma). Subsequently, findings compatible with the presence of a multidrug resistance-1 (MDR1) gene in the tumor was documented, which may explain the poor uptake of Tc-99m MIBI. The patient did not respond to intensive chemotherapeutic regimens, and died 3 months later. This case demonstrates the potential use of combined radionuclide imaging for the detection of malignant transformation of neurofibroma, as well as for predicting tumor response to chemotherapy.

Xanthogranulomatous cholecystitis: CT features with emphasis on differentiation from gallbladder carcinoma.

PURPOSE: To evaluate the computed tomographic (CT) features of xanthogranulomatous cholecystitis (XGC) and to distinguish it from gallbladder carcinoma. MATERIALS AND METHODS: Retrospective analysis was performed in 11 patients with XGC and 17 patients with gallbladder carcinoma in which the wall was thickened. The following CT features were analyzed: maximum wall thickness, intramural hypoattenuated nodules, mucosal line, patterns of wall thickening and enhancement, and the presence of stones. The changes outside the gallbladder were also compared. RESULTS: The mean thickness of the gallbladder wall was 1.8 cm in patients with XGC and 2.1 cm in patients with gallbladder carcinoma. Intramural hypoattenuated nodules were seen in all patients with XGC but in only seven patients with gallbladder carcinoma (P = .008). The mucosal line was observed in nine patients with XGC and in six with gallbladder carcinoma (P = .02). The gallbladder wall was more diffusely thickened in patients with XGC (10 of 11 patients) than in patients with gallbladder carcinoma (seven of 17 patients) (P = .01). The occurrence of changes outside the gallbladder did not differ statistically significantly. CONCLUSION: Because of a statistically significant overlap of CT features, only when intramural hypoattenuated nodules occupy a large area of the thickened gallbladder wall can the diagnosis of XGC be highly suggestive. The diagnosis of XGC at CT may indicate a less aggressive surgical approach.