Correlation between apparent diffusion coefficient and histopathology subtypes of osteosarcoma after neoadjuvant chemotherapy.

Background Neoadjuvant chemotherapy has made limb-salvage surgery possible for the patients with osteosarcoma. Diffusion-weighted magnetic resonance imaging (DWI) has been used to monitor chemotherapy response. Purpose To correlate the apparent diffusion coefficient (ADC) values with histopathology subtypes of osteosarcoma after neoadjuvant chemotherapy. Material and Methods Twelve patients with osteoblastic (n = 7), chondroblastic (n = 4), and fibroblastic (n = 1) osteosarcomas underwent post-chemotherapy DWI before limb-salvage surgery. ADCs corresponding to 127 histological tissue samples from the 12 resected specimens were compared to histological features. Results The mean ADC value of non-cartilaginous viable tumor (38/91, ADC = 1.22 ± 0.03 × 10-3 mm2/s) was significantly ( P < 0.001) lower than that of non-cartilaginous tumor cell necrosis without stroma disintegration (25/91, ADC =1.77 ± 0.03 × 10-3 mm2/s), cartilaginous viable tumor (14/91, ADC = 2.19 ± 0.04 × 10-3 mm2/s), and cystic areas including liquefied necrosis, blood space, and secondary aneurysmal bone cyst (14/91, ADC = 2.29 ± 0.05 × 10-3 mm2/s). The mean ADC value of non-cartilaginous tumor cell necrosis was also significantly ( P < 0.001) smaller than those of viable cartilaginous tumor and cystic/hemorrhagic necrosis whereas the mean ADC values were not significantly ( P > 0.05) different between viable cartilaginous tumor and cystic/hemorrhagic necrosis. Conclusion DWI allows assessment of tumor necrosis after neoadjuvant chemotherapy by ADC differences between viable tumor and necrosis in fibroblastic and osteoblastic osteosarcomas whereas viable chondroblastic osteosarcoma has high ADC and cannot be distinguished reliably from necrosis.

Comparison of Early Submucosal Enhancement and Tumor Stalk in Staging Bladder Urothelial Carcinoma.

OBJECTIVE: The purpose of this study was to compare the efficacy of submucosal enhancement on dynamic contrast-enhanced MRI (DCE-MRI) and detection of a stalk on DWI for differentiating stage T1 from stage T2 bladder urothelial carcinoma. SUBJECTS AND METHODS: Our prospective study was approved by the institutional medical ethics committee and informed consent was obtained from all patients. Fifty-nine patients (92 tumors in total) with urothelial bladder cancer underwent MRI within 2 weeks before surgery. Two image sets of T2-weighted MRI with DWI and T2-weighted with DCE-MRI were interpreted independently at 2-week intervals by two uroradiologists without any knowledge of the surgical or histologic findings. The tumor was categorized as stage T1 or lower when a stalk was evident at the tumor base on DWI or when continuous linear submucosal enhancement was detected in the early phase of DCE-MRI. Tumors without stalks or with discontinuous linear submucosal enhancement were categorized as stage T2. RESULTS: Of the 42 tumors with stalks on DWI, 41 showed continuous and one had discontinuous submucosal enhancement on DCE-MRI. In 50 carcinomas without stalks on DWI, submucosal enhancement was absent in 34, continuous in 12, and discontinuous in four. The staging accuracy of DWI (91.3%, 84/92) and DCE-MRI (91.3%, 84/92) was improved to 94.6% (87/92) by combining the interpretations of both DWI and DCE-MRI. CONCLUSION: Submucosal linear enhancement under the tumor base on DCE-MRI complements tumor stalk detection on DWI for differentiating stage T1 from stage T2 bladder urothelial carcinoma.

Multiparametric 3-T MRI for differentiating low-versus high-grade and category T1 versus T2 bladder urothelial carcinoma.

OBJECTIVE. The purpose of this study was to determine an optimal multiparametric MRI protocol for characterizing tumors of low versus high grade and differentiating tumors as T1 versus T2 for preoperative staging of bladder urothelial carcinoma. SUBJECTS AND METHODS. Thirty-nine patients underwent MRI within 1 week before surgery. Three image sets-T2-weighted plus diffusion-weighted MRI (DWI), T2-weighted plus dynamic contrast-enhanced MRI (DCE-MRI), and T2-weighted plus DCEMRI plus DWI-were independently interpreted by two readers at 2-week intervals. ROC curves were plotted for both readers to compare the diagnostic efficacy of the three sets for detrusor muscle invasion for each reader, and the areas under the ROC curve were compared by use of the Bonferroni test. The apparent diffusion coefficient (ADC) values were correlated with histopathologic grade. RESULTS. A total of 49 category T1 and T2 lesions were analyzed. The average ADC of 11 low-grade tumors (1.141 ± 0.164 × 10(-3) mm(2)/s) was significantly (p < 0.05) higher than that of 20 high-grade malignant tumors (0.766 ± 0.091 × 10(-3) mm(2)/s). Neither reader considered T1 tumors as probably having muscle invasion (category T2) in the T2-weighted plus DWI image sets or the T2-weighted plus DWI plus DCE-MRI image sets. Using the T2-weighted plus DCE-MRI sets, the two readers overstaged 13 and 15 of 36 tumors by misdiagnosing category T1 as T2. With the cutoff ADC value of 0.899 × 10-3 mm(2)/s, the sensitivity and specificity for differentiating high- and low-grade bladder urothelial carcinoma were 100% and 95%. CONCLUSION. Multiparametric MRI with T2-weighted plus DWI plus DCE technique is the optimal protocol for preoperative staging of organ-confined bladder urothelial carcinoma. The ADC of low-grade tumors is significantly higher than that of high-grade tumors with 100% sensitivity and 95% specificity at a cutoff ADC value of 0.899 mm(2)/s.

MR diffusion tensor imaging of normal kidneys.

PURPOSE: To assess the feasibility of diffusion tensor imaging (DTI) of normal kidneys and the influence of hydration state. MATERIALS AND METHODS: Ten healthy volunteers underwent renal DTI after fasting for 12 hours and 4 hours, without fasting, and following water diuresis. Medullary and cortical apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured and compared in the four different states of hydration. DTI was performed with a 3T magnetic resonance imaging (MRI) system using fat-saturated single-shot spin-echo echo planar imaging sequence. RESULTS: ADC of normal cortex (2.387 ± 0.081 × 10(-3) mm(2) /s) was significantly higher (t = 20.126, P = 0) than that of medulla (1.990 ± 0.063 × 10(-3) mm(2) /s). The FA value of normal cortex (0.282 ± 0.017) was significantly lower (t = -42.713, P = 0) than that of medulla (0.447 ± 0.022). The ADC and FA values of the left renal cortex (2.404 ± 0.082 × 10(-3) mm(2) /s, 0.282 ± 0.017) and medulla (2.002 ± 0.081 × 10(-3) mm(2) /s, 0.452 ± 0.024) were not significantly different (P > 0.05) from those of right renal cortex (2.369 ± 0.080 × 10(-3) mm(2) /s, 0.283 ± 0.018) and medulla (1.978 ± 0.039 × 10(-3) mm(2) /s, 0.443 ± 0.019). Values for ADC (×10(-3) mm(2) /s) and FA in the 12-hour fasting, 4-hour fasting, nonfasting, and water diuresis states were 2.372 ± 0.095 and 0.278 ± 0.018, 2.387 ± 0.081 and 0.282 ± 0.017, 2.416 ± 0.051 and 0.279 ± 0.023, 2.421 ± 0.068, and 0.270 ± 0.021, respectively, in cortex, 1.972 ± 0.084 and 0.438 ± 0.014, 1.990 ± 0.063 and 0.447 ± 0.022, 2.021 ± 0.081 and 0.450 ± 0.031, 2.016 ± 0.076 and 0.449 ± 0.028, respectively, in medulla. The ADC and FA values in different hydration states were not significantly different (P > 0.05). CONCLUSION: DTI of normal kidneys is feasible with reproducible ADC and FA values independent of hydration states.

Diffusion-weighted MRI in bladder carcinoma: the differentiation between tumor recurrence and benign changes after resection.

PURPOSE: To investigate the efficacy of diffusion-weighted MRI (DWI) in differentiating recurrent tumor from chronic inflammation and fibrosis after cystectomy or transurethral resection of bladder cancer. METHODS: Eleven patients with suspected tumor recurrence underwent pelvic DWI and dynamic contrast-enhanced (DCE) MRI at 3 months to 7 years following bladder cancer resection. The diagnosis was histologically confirmed in all patients by transurethral or cystoscopic resection of 27 lesions within 2 weeks of MR examinations. RESULTS: The accuracies, sensitivities, specificities, and positive predict values of DWI (92.6%, 100%, 81.8%, and 88.9%) were higher than those of DCE MRI (59.3%, 81.3%, 27.3%, and 54.2%) for detecting recurrent tumors. Using receiver operating characteristic analysis, the accuracy of DWI was significantly higher than that of DCE MRI (P < 0.05). There was no significant difference between DWI diagnosis and histopathology (P > 0.05), whereas the difference between diagnosis of DCE MRI and histopathology was significant (P < 0.05). The normalized apparent diffusion coefficients of recurrent tumors (0.697 ± 0.219) were significantly (P < 0.05) lower than those of postoperative inflammation or fibrosis (1.019 ± 0.143). CONCLUSIONS: DWI is superior to DCE MRI for differentiating recurrent bladder tumors from postoperative inflammation or fibrosis. DWI can be included in the follow-up MRI protocol after bladder cancer surgery.

3T magnetic resonance diffusion tensor imaging in chronic kidney disease.

OBJECTIVE: To investigate the relationship of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values with renal function on 3T diffusion tensor imaging (DTI) in chronic kidney disease. MATERIALS AND METHODS: Twenty healthy volunteers and 29 patients with CKD underwent DTI. The relationship among ADC, FA, and renal function was analyzed. RESULTS: Cortical and medullary ADC and FA values of patients with chronic kidney disease were lower than those of healthy volunteers (P = 0.000). Both the renal ADC and FA values correlated inversely with serum creatinine and blood urea nitrogen (P < 0.05). CONCLUSION: DTI is a feasible and non-invasive means to reflect the severity of renal function damaged.

Diagnostic and post-treatment CT appearance of biopsy proven mixed Cryptococcus and Candida cholangitis.

Cryptococcus neoformans and Candida are common opportunistic pathogens of human. There is very limited literature on Cryptococcus neoformans cholangitis or Candida cholangitis in immunocompetent patient while mixed Cryptococcus neoformans and Candida cholangitis has not been reported in the literature ever before. We hereby report the imaging findings of a case of mixed Cryptococcus neoformans and Candida cholangitis in an immunocompetent boy. The CT features included nodules in the cystic duct and common bile duct, dilatation of the intra- and extrahepatic bile ducts with mural thickening, irregular hypodense mass-like lesion extending along the bile ducts from the liver hilum to the periphery which was confirmed by the presence of enlarged and confluent lymph nodes. CT characteristics can contribute to timely diagnosis and treatment of this disease.

Sixty-four-slice computed tomography angiography of perigastric veins with image fusion.

OBJECTIVE: The objective of this study was to assess the efficacy and clinical value of 64-slice computed tomography angiography (CTA) with image fusion for demonstrating the perigastric venous anatomy. METHODS: Twenty-six patients with gastric cancer underwent abdominal CTA examinations. Computed tomography angiography of stomach and perigastric veins and arteries were reconstructed and fused using volume-rendering technique. The inflow and courses of perigastric veins as well as the spatial relationship among the perigastric veins, arteries, and stomach were compared with surgery. RESULTS: Compared with surgical findings, the visualization rate of the 7 perigastric veins on CTA was 90.9% to 100%. There was a statistically significant decrease in number of short gastric veins identified on CTA compared with surgery (P = 0.004). There was no statistically significant difference between the 2 modalities in detecting other perigastric veins including the left gastric vein, right gastric vein, right gastroepiploic vein, left gastroepiploic vein, posterior gastric vein, and gastrocolic trunk (P = 0.317, P = 0.157, P = 1, P = 1, P = 0.317, P = 1, respectively). CONCLUSIONS: Sixty-four-slice CTA with image fusion clearly depicts most of perigastric veins and their relationship with the stomach and perigastric arteries. It can facilitate gastrectomy.

Alendronate once weekly for the prevention and treatment of bone loss in Canadian adult cystic fibrosis patients (CFOS trial).

BACKGROUND: Patients with cystic fibrosis (CF) are at risk for early bone loss, and demonstrate increased risks for vertebral fractures and kyphosis. A multicenter, randomized, controlled trial was conducted to assess the efficacy, tolerability, and safety of therapy with oral alendronate (FOSAMAX; Merck; Whitehouse Station, NJ) in adults with CF and low bone mass. METHODS: Participants received placebo or alendronate, 70 mg once weekly, for 12 months. All participants received 800 IU of vitamin D and 1,000 mg of calcium daily. Adults with confirmed CF with a bone mineral density (BMD) T score of < - 1.0 were eligible for inclusion. Participants who had undergone organ transplantation or had other reported contraindications were excluded from the study. The primary outcome measure was the mean (+/- SD) percentage change in lumbar spine BMD after 12 months. Secondary measures included the percentage change in total hip BMD, the number of new vertebral fractures (grade 1 or 2), and changes in quality of life. RESULTS: A total of 56 participants were enrolled in the study (mean age, 29.1 +/- 8.78 years; 61% male). The absolute percentage changes in lumbar spine and total hip BMDs at follow-up were significantly higher in the alendronate therapy group (5.20 +/- 3.67% and 2.14 +/- 3.32%, respectively) than those in the control group (- 0.08 +/- 3.93% and - 1.3 +/- 2.70%, respectively; p < 0.001). At follow-up, two participants (both in the control group) had a new vertebral fracture (not significant), and there were no differences in quality of life or the number of adverse events (including serious and GI-related events). CONCLUSION: Alendronate therapy was well tolerated and produced a significantly greater increase in BMD over 12 months compared with placebo.

99mTc-MIBI imaging of AIDS-related Kaposi's sarcoma in the lungs.

OBJECTIVE: Pulmonary Kaposi's sarcoma (KS) occurs in more than 10% of patients with acquired immunodeficiency syndrome (AIDS) and has a high mortality rate. Prompt detection, diagnosis, and treatment reduce patient morbidity and mortality. The objective of this study was to determine the efficacy of 99mTc-hexakis-2-methoxy isobutyl isonitrile (99mTc-MIBI) imaging in detecting pulmonary AIDS-related KS. METHODS: 99mTc-MIBI imaging was performed on 72 human immunodeficiency virus-seropositive patients with bronchoscopic diagnosis of pulmonary KS (36 patients), pneumonia (22), normal tracheo-bronchial tree (11), lymphoma (2), and bronchogenic carcinoma (1). Lung uptake and lymph node detection in KS were compared on planar and single photon emission computed tomography (SPECT) scans. RESULTS: The lung/myocardium ratios on the 1-h planar images were significantly higher in KS and normal lungs than opportunistic infection. Using the lung/myocardium ratio of 1 as cutoff, the sensitivity, specificity, and accuracy of the 1-h planar images for detecting pulmonary KS were 75, 57.58, and 66.67%, respectively. Abnormal lymph node uptake, pleural/pericardial effusions, and ascites were detected more readily on SPECT. CONCLUSION: Planar 99mTc-MIBI imaging has moderate sensitivity, specificity, and accuracy for detecting pulmonary KS. SPECT is more effective in detecting abnormal lymph nodes, pleural/pericardial effusions, and ascites. 99mTc-MIBI SPECT followed by planar imaging at 40-60 min can be useful in assessing pulmonary KS.

Longitudinal analysis of vertebral fracture and BMD in a Canadian cohort of adult cystic fibrosis patients.

BACKGROUND: Vertebral fractures in patients with cystic fibrosis (CF) may contribute to an accelerated decline in lung function and can be a contraindication to lung transplantation. In this study, we examined longitudinal change in bone mineral density (BMD) and the prevalence of vertebral fractures in adult CF patients, without lung-transplant, attending a Canadian specialty clinic. METHODS: Retrospective chart review of all patients attending an Adult Cystic Fibrosis Clinic at Hamilton Health Sciences in Hamilton, Canada. Forty-nine of 56 adults met inclusion criteria. Chest radiographs were graded by consensus approach using Genant's semi-quantitative method to identify and grade fractured vertebrae. Dual x-ray absorptiometry (DXA) scans were also reviewed. RESULTS: The mean age of the cohort was 25.2 years (SD 9.4), 43% were male. The mean body mass index (BMI) was 19.8 (2.8) for males and 21.7 (5.1) for females. At baseline, the rate of at least one vertebral fracture was 16.3%; rising to 21.3% (prevalent and incident) after a 3-year follow-up. The mean BMD T-or Z-scores at baseline were -0.80 (SD 1.1) at the lumbar spine, -0.57 (SD 0.97) at the proximal femur, and -0.71 (SD 1.1) at the whole body. Over approximately 4-years, the mean percent change in BMD was -1.93% at the proximal femur and -0.73% at the lumbar spine. CONCLUSION: Approximately one in five CF patients demonstrated at least one or more vertebral fractures. Moderate declines in BMD were observed. Given the high rate of vertebral fractures noted in this cohort of adult CF patients, and the negative impact they have on compromised lung functioning, regular screening for vertebral fractures should be considered on routine chest radiographs.

Minimum joint space width and tibial cartilage morphology in the knees of healthy individuals: a cross-sectional study.

BACKGROUND: The clinical use of minimum joint space width (mJSW) and cartilage volume and thickness has been limited to the longitudinal measurement of disease progression (i.e. change over time) rather than the diagnosis of OA in which values are compared to a standard. This is primarily due to lack of establishment of normative values of joint space width and cartilage morphometry as has been done with bone density values in diagnosing osteoporosis. Thus, the purpose of this pilot study is to estimate reference values of medial joint space width and cartilage morphometry in healthy individuals of all ages using standard radiography and peripheral magnetic resonance imaging. DESIGN: For this cross-sectional study, healthy volunteers underwent a fixed-flexion knee X-ray and a peripheral MR (pMR) scan of the same knee using a 1T machine (ONI OrthOne, Wilmington, MA). Radiographs were digitized and analyzed for medial mJSW using an automated algorithm. Only knees scoring 0.05) in either sex. Females had a mean (SD) medial mJSW of 4.8 (0.7) mm compared to males with corresponding larger value of 5.7 (0.8) mm. Cartilage morphometry results showed similar trends with mean (SD) tibial cartilage volume and thickness in females of 1.50 (0.19) microL/mm2 and 1.45 (0.19) mm, respectively, and 1.77 (0.24) microL/mm2 and 1.71 (0.24) mm, respectively, in males. CONCLUSION: These data suggest that medial mJSW values do not decrease with aging in healthy individuals but remain fairly constant throughout the lifespan with "healthy" values of 4.8 mm for females and 5.7 mm for males. Similar trends were seen for cartilage morphology. Results suggest there may be no need to differentiate a t-score and a z-score in OA diagnosis because cartilage thickness and JSW remain constant throughout life in the absence of OA.

Diffusion-weighted magnetic resonance imaging of spinal infection and malignancy.

BACKGROUND AND PURPOSE: Pyogenic and tuberculous spondylitis can mimic malignancy. The purpose of this study was to deter mine the efficacy of diffusion-weighted magnetic resonance imaging in differentiating spinal infection and malignancy. METHODS: Fifty-one consecutive patients with suspected spinal infection or malignancy were enrolled in the study. Apparent diffusion coefficients (ADCs) of paraspinal soft tissue mass and normal and abnormal vertebral bone marrow were determined on the diffusion-weighted magnetic resonance images of the spine. The mean ADCs of normal and abnormal vertebral bodies in patients with confirmed infection or malignancy were compared using nonparametric tests. RESULTS: ADCs of 69 tuberculous, 9 pyogenic, and 50 malignant vertebral marrow lesions were significantly higher than ADCs of normal marrow. ADCs of malignant bone marrow and 5 paraspinal soft tissue lesions were significantly lower than tuberculosis and pyogenic infection. There was no significant difference between the ADCs of 44 adult and 25 pediatric tuberculous bone lesions or between tuberculosis and pyogenic infection. Using the cutoff ADC of 1.02x10(-3)mm2/s for bone marrow, the sensitivity, specificity, and accuracy were 60.26%, 66.00%, and 62.50%, respectively, for distinguishing infection from malignancy. The sensitivity, specificity, and accuracy increased to 94.12%, 82.35%, and 90.20%, respectively, when the ADCs of associated soft tissue lesions were higher than 1.17x10(-3)mm2/s. CONCLUSIONS: Diffusion-weighted magnetic resonance imaging has limited usefulness for differentiating spinal infection and malignancy.

Diffusion and magnetization transfer MRI of brain infarct, infection, and tumor in children.

The purpose of this study was to determine the efficacy of diffusion-weighted imaging (DWI) and magnetization transfer imaging (MTI) in the differential diagnosis of brain infarct, infection, hamartoma, and tumor in 106 children. The apparent diffusion coefficients (ADCs) and magnetization transfer ratios (MTRs) of the lesions were compared using nonparametric tests. There was an inverse relationship between ADC and MTR in subacute/chronic infarct, infection, hamartoma, arachnoid cyst, and tumor relative to normal brain parenchyma. Both ADC and MTR were reduced in acute infarct. DWI and MTI had a complementary role in the differential diagnosis of acute infarct from infection with lower MTR, from hamartoma with higher ADC, and from low-grade gliomas and benign tumors that had higher ADCs and lower MTRs. ADCs increased and MTRs decreased with the duration of infarct and lower tumor grade.

Assessment of Activity of Crohn Disease by Diffusion-Weighted Magnetic Resonance Imaging.

To assess the diagnostic efficacy of diffusion-weighted MR imaging (DWI) for evaluating inflammatory activity in patients with Crohn's disease (CD). A total of 47 CD patients underwent MR enterography (MRE) and DWI using 3 b values of 50, 400, and 800 s/mm. Apparent diffusion coefficients (ADCs) of inflamed and normal bowel wall were calculated. The conventional MRE findings and DWI signal intensities were qualitatively scored from 0 to 3. The correlation between Crohn disease activity index (CDAI) and both ADCs and magnetic resonance imaging scores was analyzed. Receiver-operating characteristic curve analysis was used to determine the diagnostic accuracy of CD activity. Of the 47 patients, 25 were active CD (CDAI≥150) and 22 were inactive (CDAI<150). Diffusion-weighted MR imaging and MRE + DWI scores of active CD were significantly higher than that of inactive CD (both P < 0.001). Apparent diffusion coefficients in inflamed segments of active CD were lower than that of inactive CD (P < 0.001). The DWI scores (r = 0.74, P < 0.001), ADCs (r = -0.71, P < 0.001), MRE scores (r = 0.54, P < 0.001), and MRE + DWI scores (r = 0.66, P < 0.001) were all correlated with CDAI. The areas under the receiver-operating characteristics curves for ADCs, DWI scores, MRE scores, and MRE + DWI scores ranged from 0.83 to 0.98. The threshold ADC value of 1.17 × 10 mm/s allowed differentiation of active from inactive CD with 100% sensitivity and 88% specificity. Diffusion-weighted MR imaging and ADC correlated with CD activity, and had excellent diagnostic accuracy for differentiating active from inactive CD.

Brain CT and MRI findings in 100 consecutive patients with intracranial tuberculoma.

OBJECTIVE: The characteristics of intracranial tuberculoma on computed tomography (CT) and magnetic resonance imaging (MRI) are not well known. The authors reviewed the features of tuberculoma on CT scans and MRI. The authors also correlated the MRI characteristics on various pulse sequences with neuropathological findings. METHODS: The charts of patients with intracranial tuberculoma were consecutively reviewed during the period from 1988 to 1999. The diagnosis of tuberculoma was based on pathology (n = 19), clinical or neuroimaging response to tuberculous chemotherapy (n = 57), or evidence of systemic tuberculosis (n = 24). Neuropathological specimens of tuberculoma were graded for the amount of fibrosis, gliosis, necrosis, and cell types (lymphocytes, macrophages, plasma cells). RESULTS: One hundred patients (43 men) were identified. The age range was 1 to 75 years (mean = 30 y). The number of lesions ranged from 1 to > 100 (mean = 4.5 lesions/patient). Thirty-one patients had solitary lesions, whereas 69 had multiple lesions. Thirty-seven patients had hydrocephalus. After contrast administration, > 450 lesions were seen on CT and MRI images in all 100 scans. The diameter of these enhancing lesions ranged from 1 mm to 5 cm. Lesions > 1 cm showed varied enhancement, including irregular shapes, ringlike shapes, open rings, and lobular patterns. Targetlike lesions were seen in only 2 patients. Other features included cortical and subcortical infarcts (12 patients), calcification (10% of lesions), edema (33 patients), meningeal enhancement (12 patients), mass effect, and/or midline shift (18 patients). A hypointense core with a hyperintense rim was the most common signal characteristic on T2-weighted MRI. The central hypointensity on T2-weighted and fluid-attenuated inversion recovery (FLAIR) images reflected extensive necrosis and hypercellularity. CONCLUSION: Multiple tuberculomas and infratentorial locations were more common in the authors' patient population than in previous reports. The MRI signal characteristics of intracranial tuberculoma are extremely diverse. An isointense or hypointense core with a hyperintense rim on T2-weighted and FLAIR images is the most common presentation. Core hypointensity of lesions on these images is related to necrosis and the large number of cells.

Cerebral MR venography.

This paper illustrates the technique and clinical use of cerebral MR venography (MRV). Dural sinus thrombosis is detected by both two-dimensional time-of-flight (TOF) and three-dimensional phase-contrast (PC) techniques. Venous angiomas are demonstrated by the three-dimensional PC method. The arterial feeders, nidus and draining veins of cerebral arteriovenous malformation (AVM) can be visualized on contrast-enhanced TOF three-dimensional MR angiogram. The high-flow draining veins of cerebral and dural AVMs, vein of Galen malformation and carotid cavernous fistula are better seen on contrast-enhanced three-dimensional gradient-echo MRV.

Gadolinium-enhanced MR angiography of spinal arteriovenous malformation.

Patients with spinal arteriovenous malformation (AVM) have progressive or fluctuating neurological dysfunction because of hemorrhage, venous hypertension, vascular steal phenomenon, or mass effect from venous varicosity. Spinal AVM is classified into four types based on angiographic and operative findings. Conventional diagnostic methods include magnetic resonance imaging (MRI), supine myelogram, and angiogram. MRI can localize the vascular nidus in the cord, but it may sometimes be normal. Spinal angiogram is the definitive diagnostic modality. It is technically demanding and time consuming, requiring catheterization of all spinal vascular pedicles. MR angiography is fast and multiplanar, and it may shorten the duration of catheter angiography by demonstrating the level of feeders. Images of MRI, magnetic resonance angiography (MRA), and catheter angiogram are presented to illustrate the correlation and diagnosis of spinal AVM.

Fatty tissue breast lesions.

Hamartoma, lipoma and fat necrosis are benign fatty tissue lesions that may present as breast lumps. The mammographic appearance may be distinctive allowing imaging diagnosis without biopsy. The characteristic feature of hamartoma is that of a compressible mass containing radiolucent fat interchanged with dense fibrous connective tissue surrounded by a thin radioopaque pseudocapsule. Lipomas are radiolucent with well-defined thin smooth capsule. Twenty-seven percent of fat necrosis appears as discrete round or oval radiolucent oil cyst with thin capsule and egg-shell calcification.

MRI of gynecological neoplasm.

MRI is multiplanar, has large field of view, superior contrast resolution and no known adverse effect on the reproductive potential of ovaries. It is useful for characterizing solid, cystic or necrotic tissue, blood and fat. Contrast-enhanced MRI is also a comprehensive examination of the entire pelvis including lymph nodes, peritoneum, pelvic sidewalls, bone and muscles. It provides information about areas difficult to assess surgically, can refine staging classification, assists in planning surgery or radiotherapy and may be more cost-effective by limiting use of surgery. This is a pictorial essay of MRI assessment of female pelvic neoplasm.