Contrast-enhanced Material-enhanced Magnetic Resonance Imaging Research Articles

Contrast-enhanced MR imaging in acute lumbar radiculopathy: a pilot study of the natural history.

To prospectively study clinical findings and contrast material-enhanced magnetic resonance (MR) images over time in patients with acute lumbar radiculopathy. Twenty-five patients underwent physical examination and MR imaging at presentation, 6 weeks, and 6 months. Initial symptoms and clinical course were correlated with type, size, location, and enhancement of disk herniations. Eighteen patients had a herniated nucleus pulposus (HNP) at one or more levels, two had synovial cysts and stenosis, and five had normal findings. Patients with an HNP had marginally more severe neurologic symptoms than did patients without an HNP (P = .07) at presentation. Twenty-two patients completed the 6-week examinations and 14 patients the 6-month examinations; three patients were eliminated from the study after surgical treatment. Among HNPs larger than 6 mm, substantial reduction in size was noted in 36% at 6 weeks and in more than 60% at 6 months after presentation. Agreement between clinical and MR findings for level and side of HNP and radicular symptoms was excellent. There was no correlation of pain and disability with disk size, behavior, or type.

Adnexal masses: accuracy of characterization with transvaginal US and precontrast and postcontrast MR imaging.

To determine the accuracy of transvaginal ultrasound (TVUS) and of precontrast and contrast material-enhanced magnetic resonance (MR) imaging in the differentiation of adnexal masses. Five blinded readers analyzed images of 80 masses in 72 patients. MR and TVUS images were interpreted in separate sessions. Findings were confirmed at surgery or laparoscopy. Higher diagnostic accuracy was attained with MR imaging in mature cystic teratomas and endometriomas. However, better accuracy was achieved with contrast-enhanced MR imaging and TVUS in simple cysts, cystadenomas, and malignant tumors because internal details could be visualized. Receiver operating characteristic study indicated that observer confidence was significantly higher with contrast-enhanced MR imaging than with precontrast MR imaging (P = .011) or TVUS (P = .002) in the differentiation of benign and malignant masses. Contrast-enhanced MR imaging is superior to precontrast MR and TVUS imaging in the characterization and differentiation of adnexal masses.

Enlarged mediastinal lymph nodes in bronchogenic carcinoma: assessment with dynamic contrast-enhanced MR imaging. Work in progress.

To determine whether dynamic contrast material-enhanced magnetic resonance (MR) imaging can help differentiate between malignant and benign mediastinal lymph nodes (MLNs) in bronchogenic carcinoma. Nine patients with biopsy-proved lung carcinoma underwent dynamic contrast-enhanced MR imaging before undergoing thoracic surgery. MR studies included spin-echo, electrocardiographically gated axial and coronal sequences and transaxial gradient-echo breath-hold sequences, which were performed after administration of a bolus of gadoterate meglumine. The enhancement curves were established on the basis of mean signal intensities from regions of interest at the level of tumor and the enlarged MLN. MR images were compared with pathologic specimens obtained at surgical resection. Metastatic MLNs exhibited their peak enhancement at 60-80 seconds, with a slow decrease until 6 minutes. Granulomatous and anthracotic lymph nodes displayed a slight enhancement, with no peak within 6 minutes (P < .01). Dynamic contrast-enhanced MR images may provide informative data about the nature of enlarged MLNs in the preoperative assessment of lung carcinoma. Further studies are needed to investigate its usefulness in clinical practice.

Diagnosis of osteomyelitis: utility of fat-suppressed contrast-enhanced MR imaging.

To assess the value of fat-suppressed contrast material-enhanced magnetic resonance (MR) imaging in the diagnosis of osteomyelitis. T1- and T2-weighted MR imaging was performed in 51 cases of suspected osteomyelitis. Nonenhanced and contrast-enhanced T1-weighted fat-suppressed MR images were also obtained. Three-phase bone scan results were available for 30 cases. Complicating clinical factors, including chronic osteomyelitis (n = 26), postoperative state (n = 17), and neuropathic disease of the foot (n = 5), were identified in 73% of cases. In the diagnosis of osteomyelitis, scintigraphy demonstrated a sensitivity of 61% and specificity of 33%. For nonenhanced MR imaging, sensitivity was 79% and specificity was 53%. For fat-suppressed contrast-enhanced imaging, sensitivity was 88% and specificity was 93%. In diagnosing osteomyelitis in patients with complicating clinical factors, fat-suppressed contrast-enhanced MR imaging was significantly more sensitive than scintigraphy (P = .04) and significantly more specific than nonenhanced MR imaging (P = .02) or scintigraphy (P = .008).

MR imaging of avascular necrosis and transient marrow edema of the femoral head.

The value of high spatial resolution and contrast material-enhanced magnetic resonance (MR) imaging was assessed in 69 patients with either femoral head avascular necrosis (AVN) or transient bone marrow edema lesions. An AVN lesion was typically a well-demarcated epiphyseal area of variable signal intensity. A transient bone marrow edema lesion appeared as an ill-delimited low-signal-intensity epiphyseal area on T1-weighted images that converted to a high-signal-intensity area on T2-weighted images. T1- and T2-weighted spin-echo images helped distinguish from AVN lesions some transient lesions apt to simulate the segmental pattern of AVN lesions. T2-weighted images also helped detect necrotic tissue in some unusual AVN lesions that mostly showed ill-delimited edemalike marrow changes. In some cases, contrast-enhanced MR images may increase diagnostic confidence by showing homogeneous hypervascularization in bone marrow edema lesions and by depicting hypovascular marrow areas in AVN lesions. The authors believe sequential MR imaging is valuable in the assessment of equivocal femoral head lesions.

Evaluation of myocardial perfusion abnormalities with gadolinium-enhanced snapshot MR imaging in humans. Work in progress.

To determine whether myocardial perfusion abnormalities could be detected in patients with coronary artery disease by means of contrast material-enhanced magnetic resonance (MR) images, a snapshot imaging technique was used in six patients with coronary artery disease and four healthy subjects in conjunction with pharmacologic stress (dipyridamole infusion) and bolus injection of gadopentetate dimeglumine. MR images from all patients and healthy subjects were quantitatively analyzed to define spatial changes in signal intensity after administration of dipyridamole and gadopentetate dimeglumine. The resultant findings were compared with findings on thallium-201 scintigrams obtained after administration of dipyridamole and on coronary arteriograms in all patients. Nine myocardial regions supplied by stenosed arteries showed diminished levels of signal intensity after infusion of the contrast agent compared with those of normally perfused regions. These findings were in agreement with those obtained with T1-201 scintigraphy (in eight of nine regions) and arteriography. Thus, contrast-enhanced high-speed MR imaging with use of dipyridamole enabled detection of regional perfusion abnormalities in humans.