Bone marrow necrosis in bone marrow transplantation: the role of MR imaging

We describe an ALL patient who developed extensive bone marrow necrosis at the time of relapse 2 months after allogeneic bone marrow transplantation from an HLA-identical sibling. The excruciating and diffuse bone pain, fever and precipitous drop in peripheral blood counts were characteristic. This case illustrates the importance of repeat bone marrow biopsies for the diagnosis of disease relapse and the potential application of MR imaging in the assessment of patients with bone marrow necrosis.     

Diffusion-weighted MR imaging of acute cerebral ischemia

Diffusion-weighted MR imaging has been used in studies on experimental animal models and on patients with acute cerebral ischemia. Compared with CT and conventional MR techniques, diffusion-weighted imaging can provide earlier and more precise detection of the location and the extent of an ischemic lesion during the critical first few hours after the onset of stroke. Quantitative apparent diffusion coefficient (ADC) mapping of the brain water can also be carried out by recording a series of diffusion-weighted images with different amplitudes of the displacement encoding gradients. ADC maps can provide important information about the extra- and intracellular water homeostasis. ADC reduction of the tissue water is one of the early signals of the pathophysiological cascade resulting from ischemic tissue injury. Diffusion MR imaging has become a valuable tool in stroke research. It may also prove a valuable tool in monitoring the efficiency of therapeutic effects in stroke patients. It is our intention to provide an overview of the recent development in this area with emphasis on the diffusion-weighted MR techniques, and to discuss the possible underlying biophysical mechanisms responsible for the contrast of diffusion-weighted imaging.     

MR imaging of edema accompanying benign and malignant bone tumors

To evaluate the incidence, quantity, and presentation of intra- and extraosseous edema accompanying benign and malignant primary bone lesions, the magnetic resonance (MR) studies of 63 consecutive patients with histologically proven primary bone tumors were reviewed. MR scans were assessed for the presence and quantity of marrow and soft tissue edema and correlated with peroperative findings, resected specimens and follow-up data. The signal intensity and enhancement of tumor and edema prior to and after intravenous administration (if any) of gadolinium-labeled diethylene triamine pentaacetate (Gd-DTPA) was analyzed. Marrow edema was encountered adjacent to 8 of 39 malignant tumors and 14 of 24 benign lesions. Soft tissue edema was found accompanying 28 of 39 malignancies and 10 of 24 benign disorders. On unenhanced T1-weighted MR images tumor and edema were difficult to differentiate. Tumor inhomogeneity made this differentiation easier on T2-weighted sequences. In 36 patients the contrast medium Gd-DTPA was used. Edema was present in 27 of these patients and the respective enhancement of tumor and edema could be compared. Edema always enhanced homogeneously, and in most cases it enhanced to a similar degree as or more than tumor. Marrow and, more specifically, soft tissue edema is a frequent finding adjacent to primary bone tumors. The mere presence and quantity of marrow and soft tissue edema are unreliable indicators of the biologic potential of a lesion. Unenhanced MR scans cannot always differentiate between tumor and edema, but the administration of Gd-DTPA is of assistance in differentiating tumor from edema.(ABSTRACT TRUNCATED AT 250 WORDS)     

Diffusion-weighted MR imaging in hypertensive encephalopathy: clues to pathogenesis

We investigated the effects of organic buffers on the NO-like biological activities of ONOO-. In HEPES buffer (50 mM), ONOO- (1 mM) induced a 20-fold increase in endothelial cGMP accumulation and the effect was comparable to that elicited by a maximally active concentration of the NO donor DEA/NO. ONOO- produced a 12-fold increase of cGMP in MOPS buffer (50 mM), but was virtually inactive in phosphate buffer (50 mM). Electrochemical detection of NO showed that the biological effects of ONOO- in HEPES or MOPS were due to accumulation of compounds that released NO in the presence of copper ions. CuCl2-induced formation of NO was completely blocked by the Cu(I) chelator neocuproine but unaffected by the Cu(II) chelator cuprizone, pointing to a Cu(I)-catalyzed decomposition pathway. Formation of NO from ONOO- was not detectable in phosphate buffer, in agreement with the lack of effect of ONOO- on cGMP accumulation in this buffer. These data demonstrate that certain buffer components present in cell culture media may yield artificial results in experiments with authentic ONOO-.     

Diffusion-weighted MR imaging in a case of dissociative amnesia

BACKGROUND: Management of thyroid cancer in pregnancy is controversial, as evidenced by disagreement in recommendations cited in leading obstetrics textbooks. Most thyroid carcinomas are well differentiated and pursue an indolent course. Many physicians recommend delay in surgical therapy until after delivery because of operative morbidity. CASE: A 27-year-old primigravida was found to have a solitary thyroid nodule at her initial obstetrics appointment. Fine needle aspiration was consistent with papillary carcinoma. Although detected at 8 weeks' estimated gestational age (EGA), the decision was made to defer surgical therapy until postpartum. The patient was referred to a tertiary care facility at 24 weeks' EGA secondary to rapid growth of the nodule. Surgery performed at that time revealed invasive disease. CONCLUSION: Review of the literature suggests that delay in definitive therapy stems from early reports of fetal loss related to surgery, but contemporary data suggest that the risk of fetal loss related to surgery is minimal.     

MR imaging of tibial plateau fractures

Magnetic resonance (MR) images of five patients with acute tibial plateau fractures are presented and correlated with both clinical examination and findings at surgical intervention. The role of MR imaging in the evaluation of both osseous and soft tissue deformity in acute trauma, specifically in patients with tibial plateau fractures is discussed. The value of MR imaging as an alternative to computed tomography and arthroscopic evaluation of these patients is emphasized.     

Deep benign fibrous histiocytoma of the knee: CT and MR features with pathologic correlation

Magnetic resonance imaging and pathologic findings in a 28-year-old patient with a giant deep benign fibrous histiocytoma in the popliteal fossa of the right knee are described. The MR imaging findings include a well-delineated oval mass with low signal intensity on T1-, and high signal intensity on T2-weighted, images, and marked peripheral contrast enhancement. To the best of our knowledge, this is the first report on the MR findings in this entity.     

Pulmonary complications after bone marrow transplantation: high-resolution CT and pathologic findings

The explosion of new knowledge about the complex mechanisms mediating high blood pressure is providing new targets for drug therapy of hypertension and other cardiovascular disorders. This article reviews the current status of several new approaches in the management of hypertension, including vasopressin antagonists, natriuretic peptide clearance inhibitors, endothelin antagonists, renin inhibitors, angiotensin receptor antagonists, and selective T-type calcium ion channel antagonists.     

Diffusion-weighted MR imaging with a single-shot echoplanar sequence: detection and characterization of focal hepatic lesions

BACKGROUND: The aim of this study was to establish the feasibility, safety, and diagnostic accuracy of the dipyridamole echocardiography test in patients with severe aortic valve stenosis for noninvasive detection of coexisting coronary artery disease. METHODS: The high-dose dipyridamole echocardiography test was performed in 52 patients with severe aortic stenosis; all patients also underwent coronary angiography, independent of test results, before cardiac operation. RESULTS: The dipyridamole echocardiography test was completed without major complications. One patient had transient atrial fibrillation that was reversed by aminophylline. Thirty-one patients (60%) had a negative test result; all had normal coronary arteries. Ten of the 21 patients (48%) with a positive test result had coexisting coronary artery disease. The positive predictive value of the dipyridamole echocardiography test for detection of coronary disease in patients with severe aortic stenosis was 48%. The negative predictive value was 100%. The sensitivity was 100% and the specificity was 74%. CONCLUSIONS: Dipyridamole echocardiography is a safe and feasible tool in patients with severe aortic stenosis eligible for a cardiac operation. A negative test result reliably rules out a significant stenosis, whereas a positive one is much less accurate in predicting coronary artery disease.     

Diffusion-weighted MR imaging: diagnostic accuracy in patients imaged within 6 hours of stroke symptom onset

We evaluated the agreement between wedged hepatic vein pressure (WHVP), portal vein pressure (PVP), and its relationship with portal hemodynamics in 21 patients with HCV-related cirrhosis with esophageal varices. Direct measurements of the portohepatic gradient (HVPG) were obtained by ultrasound-guided fine needle puncture of the right hepatic and the portal veins. In five cases PVP was 6.4-10.4 mm Hg higher than WHVP. In 12 cases measurements were similar (WHVP - PVP < or = 3 mm Hg). In the remaining four cases WHVP was 3.6-9.6 mm Hg higher than PVP. WHVP and PVP agreement was not related to HVPG mean value, Child-Pugh score, or grading of esophageal varices. By contrast, the difference between WHVP and PVP was inversely related to the portal flow velocity (P = 0.053) and directly related to the portal vascular resistance (P = 0.02). Whereas the portal branches were visualized in patients with WHVP lower or similar to PVP, a predominant left portosystemic collateral flow was observed in patients with WHVP > PVP. Our data point out that, in patients with cirrhosis due to hepatitis C virus infection, discrepant HVPG values reflect true hemodynamic differences.     

Carpal tunnel syndrome: staging of median nerve compression by MR imaging

The purpose of this prospective study was to determine the potential of MR imaging to depict morphologic alterations of the median nerve correlating with the stage of carpal tunnel syndrome (CTS). Eighteen wrists of normal subjects and 81 wrists of patients with CTS were examined. MR imaging was performed with proton-density- and T2-weighted spin-echo sequences. Staging of CTS was done on the basis of clinical and electrophysiological testing, including evaluation of the number of previous steroid infiltrations in conservative treatment. Median nerve flattening, cross-sectional area, and signal intensity were measured from the distal radius to the end of the carpal tunnel. Delineation and structure of the median nerve were recorded qualitatively by two experienced radiologists in consensus. Three major MR imaging criteria of early CTS were (a) isolated prestenotic and intracarpal swelling of the median nerve (P < .01), (b) the absence of significant flattening, and (c) a generalized increase in signal intensity retrograde to the distal radius (P < .01). The nerve showed sharply delineated contours and a homogeneous signal pattern. Advanced CTS was characterized by retrograde swelling of the median nerve to the distal radius (P < .01) and decreased signal intensity (P < .05). Demarcation of the nerve became poorer, and its signal pattern appeared fasciculated. After steroid infiltration, the median nerve was difficult to delineate, showed an inhomogeneous structure, and swelling was less pronounced than without steroid infiltration (P < .05). MR imaging yields typical morphologic findings that correlate with the duration and severity of median nerve compression. Hence, MR imaging allows staging of median nerve compression in CTS and thus may contribute to therapeutic decision-making.     

High-resolution MR imaging of stage I cervical neoplasia with a dedicated transvaginal coil: MR features and correlation of imaging and pathologic findings

OBJECTIVE: The purposes of this study were to assess the appearance of stage 1 neoplasia of the cervix by high-resolution MR imaging with an enveloping transvaginal receiver coil and to correlate the imaging findings with the pathologic findings. SUBJECTS AND METHODS: Fifteen patients (25-73 years old; mean, 40 years old) with clinical stage I disease were examined with a 37-mm-diameter ring-design solenoid receiver coil placed around the cervix. Axial 2.5-mm contiguous slices were obtained with a field of view of 10-15 cm on a 1.0-T HPQ Vista scanner with T1-weighted (660/20 msec [TR/TE]) and T2- weighted (2500/80 msec) spin-echo sequences and dynamic gradient-echo sequences during injection of gadopentetate dimeglumine (0.1 mmol/kg). Ten patients subsequently underwent Wertheim's hysterectomy, two underwent radiotherapy, two underwent extended cone biopsy for microinvasive disease, and one underwent a punch biopsy. For seven of 10 patients who had a hysterectomy, the widths of the tumor and the residual stroma were measured at eight radial points on the transverse images and at corresponding points on the histologic specimens at 5, 10, 15, 20, and 25 mm from the ectocervix. We then compared the widths of the tumor and the stroma on images and histologic specimens at each of these 40 points. Tumor volumes were calculated from the MR imaging and pathologic data and compared. For the other three patients, detailed MR imaging-pathology correlation was not possible because of multifocal tumor distribution (two patients) and insufficient detailed pathologic data (one patient). RESULTS: Three carcinoma types were recognized. Squamous carcinoma (nine cases) was seen as a centrally expanding intermediate-signal-intensity mass, whereas oat (small)-cell carcinoma (one case) and clear-cell carcinoma (one case) showed a multifocal distribution. For patients who had a radical hysterectomy, we noted good agreement between the widths of the tumor and the stroma determined by MR imaging and histology. Tumor volumes were determined to be 0-28.2 cm3 by MR imaging and 0-18.4 cm3 by pathology. We observed tumor extension into the immediate parametrium in four patients by MR imaging; one of these cases was not confirmed at surgery. Parametrial extension was not underestimated by MR imaging in any case. CONCLUSION: High-resolution imaging of the cervix with a transvaginal coil provides accurate assessment of the intra- and extracervical extents of tumors in clinical stage 1 cervical neoplasia.     

The normal and pathologic ischiorectal fossa at CT and MR imaging

A wide spectrum of disease processes involve the ischiorectal fossa, including congenital and developmental lesions; inflammatory, traumatic, and hemorrhagic conditions; primary tumors; and pathologic processes outside the ischiorectal fossa with secondary involvement. Both computed tomography (CT) and magnetic resonance (MR) imaging are useful in the definitive diagnosis of these pathologic conditions, with MR imaging being the modality of choice because of its superior contrast resolution and multiplanar capability. In Gartner duct cyst, both CT and MR imaging demonstrate a well-defined, round mass; in tailgut cyst, CT demonstrates a well-defined retrorectal mass with a solid or cystic appearance. MR imaging in particular plays a major role in the assessment of fistula in ano, infection, and hematoma. Lipoma and pelvic plexiform neurofibroma typically have low attenuation and high signal intensity at CT and MR imaging, respectively. Recurrent rectal tumor appears at both modalities as an irregular soft-tissue mass with or without central necrosis in the presacral space, perineum, or pelvic sidewall. Familiarity with the imaging features and differential diagnoses of various ischiorectal pathologic processes will facilitate prompt, accurate diagnosis and treatment.     

Cranial bone flap fixation clamps: compatibility at MR imaging

To evaluate the compatibility of a commercially pure titanium aneurysm clip associated with magnetic resonance (MR) imaging at 1.5 T. Artifacts of the Spetzler titanium aneurysm clip were compared with those produced by six different nonferromagnetic aneurysm clips. With the titanium clip, no magnetic attraction was present, heating was minor, and the artifacts involved a small signal void. With the six other aneurysm clips, artifacts were larger. The presence of Spetzler titanium aneurysm clips is safe at MR imaging at 1.5 T or less.     

Tuberculous tenosynovitis of the flexor tendons of the wrist: MR imaging with pathologic correlation

A 3-year-old child with a patent arterial duct underwent percutaneous transcatheter occlusion using Rashkind's "double umbrella" technique. The procedure, using a 17 mm device, was uncomplicated. An echocardiogram done 6 hr later showed a mobile 5 x 3 mm thrombus on the pulmonary aspect of the device. The thrombus resolved after 24 hr of intravenous heparin.     

MR appearance at different ages of osteoporotic compression fractures of the vertebrae

PURPOSE: To assess whether the expression of estrogen-induced protease, cathepsin D, might facilitate biological subgrouping of patients with breast carcinomas, and accordingly, its potential applicability in clinical oncology. PATIENTS AND METHODS: This study includes 70 patients with histologically confirmed breast carcinoma. Pathological findings were classified according to tumor size (T) and the presence or absence of metastases in regional lymph nodes (N). Steroid hormone receptor (SR) density as well as cathepsin D concentrations were assayed in the cytosol of breast carcinomas in accordance with the recommendation of the EORTC. RESULTS AND DISCUSSION: Statistically significant direct correlations were observed between cathepsin D expression and axillary node status as well as SR status. However, it is important to point out that in spite of these statistically significant findings, there were no biologically significant associations due to a wide range of individual cathepsin D values. Baseline levels of cathepsin D expression were found in patients with SR-negative status and node-negative tumors as well as in patients with SR-negative status and tumors of 相似文献   

Detection of neuroblastoma in the bone marrow: biopsy versus aspiration

OBJECTIVES: To determine the clinical effects of a change from postural drainage (PD) to positive expiratory pressure chest physiotherapy (PEP) in children with cystic fibrosis (CF) and symptoms of gastro-oesophageal reflux (GOR). To measure the effects of PD on GOR in children with CF. METHODS: Study 1: Six adolescents with CF and symptoms of GOR during PD were changed to upright PEP physiotherapy. The effects on lung function, reflux symptom scores and annual hospital days were measured. Study 2: Twenty-four children with CF (mean age 11 years) and symptoms suggestive of GOR underwent 24-h pH monitoring, including periods of chest physiotherapy. RESULTS: Study 1: All six patients reported a reduction in reflux symptoms during PEP therapy (P < 0.001). Lung function parameters improved during the first 6 months of PEP (P < 0.001). This improvement was sustained for a further 18 months. Annual hospital days decreased significantly (P < 0.0005). Study 2: Nine of 24 patients (37.5%) had pathological GOR. Reflux episodes were significantly increased during PD (P < 0.0001), as was fractional reflux time (P < 0.01). CONCLUSIONS: Upright PEP physiotherapy may be more appropriate than PD in selected patients with CF and symptomatic GOR. The role of GOR as a cofactor in the progression of pulmonary disease in CF needs further evaluation.     

In-phase and out-of-phase MR imaging of bone marrow: prediction of neoplasia based on the detection of coexistent fat and water

OBJECTIVE: The purpose of this study was to determine if gradient-echo MR imaging with TEs selected with fat and water in phase and out of phase can help predict the likelihood of neoplastic or nonneoplastic lesions in bone marrow. SUBJECTS AND METHODS: Thirty consecutive patients with 31 suspected bone marrow lesions underwent MR imaging, including two spoiled gradient-echo sequences identical in all parameters except TE, which was chosen such that fat and water were either in phase or out of phase. Relative ratios of the abnormal bone marrow signal intensity and a control site on the in-phase and out-of-phase images were expressed. The images were also assessed independently by two reviewers who were unaware of the patients' identities and clinical histories. Reviewers assessed decreased marrow signal intensity relative to control sites on the out-of-phase and in-phase images. Pathologic confirmation was obtained in 16 patients (17 lesions); the remainder of patients had either established diagnoses or determination of benignity based on stability of findings at 1 year. Relative ratios were compared with the Student's t test and receiver operating characteristic (ROC) curve analysis, and the reviewers' scores were evaluated with ROC curve analysis. RESULTS: The relative signal-intensity ratios were 1.03 +/- 0.13 for the neoplastic group and 0.62 +/- 0.13 for the nonneoplastic group (p < .0001). ROC curve analysis of the signal-intensity ratios showed a z-score of .99. A ratio cutoff value of 0.81 resulted in a 95% sensitivity and a 95% specificity for detection of neoplasm. Both reviewers achieved 100% sensitivity and 94-100% specificity for detection of neoplasms. CONCLUSION: In-phase and out-of-phase gradient-echo MR imaging of bone marrow signal-intensity abnormalities can help predict the likelihood of neoplastic or nonneoplastic lesions.     

Thoracic aortic dissection: diagnosis with transesophageal echocardiography versus MR imaging

PURPOSE: To compare transesophageal echocardiography (TEE) and magnetic resonance (MR) imaging in the diagnosis of dissection of the thoracic aorta. MATERIALS AND METHODS: Thirty-one consecutive patients with clinically suspected aortic dissection and 10 postoperative patients underwent transesophageal color Doppler echocardiography and MR imaging. Imaging results were compared at independent double-blind readings. Final diagnosis was obtained from consensual review of all corroborative studies. RESULTS: MR imaging depicted the intimal flap in 95% of aortic dissections; TEE, in 86% (P < .05). In surgical patients, the sensitivity of MR in detection of residual dissection was 100% versus 86% with TEE (P < .05). The inferior extent of the dissected lumen was seen only with MR imaging. False-positive results occurred in two cases with TEE and in one with MR imaging. CONCLUSION: MR imaging is superior to TEE in the evaluation and follow-up of dissection of the thoracic aorta. Because the availability of MR is limited, however, TEE should remain the standard modality for diagnosis.     

Evaluation of tibial plateau fractures: efficacy of MR imaging compared with CT

OBJECTIVE: CT is often used after plain films to evaluate fractures of the tibial plateau. Because MR imaging can show associated soft-tissue injuries as well as fractures, we hypothesize that MR is superior to CT for imaging these injuries. Accordingly, we compared the efficacy of MR imaging and CT in 22 patients with tibial plateau fractures. SUBJECTS AND METHODS: CT with two-dimensional reconstruction and MR examinations were performed in 22 patients with tibial plateau fractures. The images were interpreted by four radiologists and two orthopedic surgeons. Findings on CT scans and plain films were used to determine the configuration of the fractures and to classify them according to the Schatzker system. This was done with findings on MR images and plain films at a separate session. The MR images were also evaluated for ligamentous and meniscal injuries. A qualitative side-by-side comparison of two-dimensional CT scans and MR images for depiction of fracture configuration was done. Imaging results were correlated with observations from physical examinations in all patients and with surgical findings in 12 patients. RESULTS: All of the six types of fractures of the Schatzker classification were observed in this series. Comparison of two-dimensional CT reconstructions and MR images for depiction of fracture configuration revealed that the two techniques were equal in 14 patients, MR imaging was superior to CT in five patients, and CT was superior to MR imaging in three patients (who had very complex and comminuted fractures). In addition, MR imaging showed 12 complete ligamentous tears and 15 partial ligamentous tears in 15 (68%) of the 22 patients. MR showed meniscal injuries in 12 (55%) of the 22 patients. CONCLUSION: MR imaging was equivalent or superior to two-dimensional CT reconstruction for depiction of fracture configuration in most patients. In addition, MR showed significant soft-tissue injuries. We believe that MR imaging is the preferable imaging technique for most patients with fractures of the tibial plateau.