Peter Uhrmeister

Contrast-Enhanced Subtraction MR Angiography in Occlusive Disease of the Pelvic and Lower Limb Arteries: Results of a Prospective Intraindividual Comparative Study with Digital Subtraction Angiography in 76 Patients

PURPOSE The purpose of this work was to evaluate the feasibility and clinical use of MR angiography (MRA) for examining the pelvic and lower limb arteries in patients with arterial occlusive disease. METHOD Seventy-six patients with clinical signs of peripheral arterial occlusive disease were included in the study. MRA was performed using a fast contrast-enhanced high-resolution 3D technique that covered the area from the distal abdominal aorta to the distal lower limbs in two examination steps. RESULTS In all patients, diagnostic images comparable with those of conventional intraarterial digital subtraction angiography (DSA) could be obtained. No false-negative findings were seen in the iliac, femoral, or popliteal arteries. Ten to 16% of the mild stenoses and 6-14% of the severe stenoses, mainly in the crural vessels, were overgraded compared with intraarterial DSA. Particularly in patients with proximal severe obstructions or occlusions, the crural segments could be depicted more clearly due to decreased arterial runoff in conventional angiography. CONCLUSION The consistency of the excellent depiction of the vascular territories of the distal aorta and the pelvic and lower limb arteries in a standardized setting suggests great potential for the use of MRA in the primary diagnosis of peripheral arterial occlusive disease.

Comparative diagnostic accuracy of magnetic resonance imaging and immunoscintigraphy for detection of bone marrow involvement in patients with malignant lymphoma.

PURPOSE To compare the diagnostic accuracy of magnetic resonance imaging (MRI) and immunoscintigraphy (IS) for detection of bone marrow infiltration in malignant lymphoma. PATIENTS AND METHODS In 32 patients with Hodgkins disease (HD) or non-Hodgkins lymphoma (NHL), MRI of the axial skeleton and whole-body IS using technetium-99m (99mTc)-labeled monoclonal antibodies were reviewed and compared with iliac crest biopsies. Criterion for marrow infiltration was a positive biopsy or concordant positive results of MRI and IS. RESULTS In 16 patients (50%), MRI, IS, and iliac crest biopsies were negative for marrow infiltration. Iliac crest biopsy showed infiltration in only four patients (13%). Infiltration was missed in two of 32 patients with IS and in one patient with MRI. In one additional patient, MRI was false-positive because of pelvic hematopoietic hyperplasia. A subset of nine patients (28%) with negative biopsies had bone marrow involvement according to MRI and IS with identical location and pattern of infiltration. In eight of these nine patients, diagnostic imaging indicated marrow involvement only in noncrest marrow. Subsequent biopsy confirmed infiltration in five patients. The clinical course suggested true-positive imaging results in the remaining four patients. Two patients (6%) remained equivocal. Overall concordance of MRI and IS for marrow infiltration was 88% (28 of 32 patients). CONCLUSION Diagnostic imaging is essential for optimal staging in malignant lymphoma, as blind biopsies appear to have low sensitivity for bone marrow infiltration because of frequent involvement in noncrest marrow. both imaging modalities show a high rate of detection of bone marrow infiltration.

Contrast enhanced MR angiography in the assessment of relevant stenoses in occlusive disease of the pelvic and lower limb arteries: diagnostic value of a two-step examination protocol in comparison to conventional DSA

INTRODUCTION/OBJECTIVES Contrast-enhanced MRA (ce-MRA) has been claimed by many authors as a replacement of conventional angiography evaluating peripheral arterial occlusive disease. However, reliable detection of relevant stenoses (>70%) has to be provided for planning vascular interventions. Only few data in the literature focuses on this crucial problem. The purpose of this study was to evaluate this topic using a two-step body-coil-based MRA protocol. METHODS AND PATIENTS Forty three patients presenting with 82 stenoses >/=50% and 61 stenoses >70% on conventional catheter angiogram received fast Gadolinium-DTPA-enhanced high resolution 3D MR angiography at 1.5 T covering the pelvic and peripheral vascular tree in two examination steps using the body-coil. The data were evaluated double-blinded by three readers distinguishing moderate (50-70%) from severe stenoses (>70%). RESULTS Overall sensitivity/specificity/accuracy was 84/60/70% evaluating 143 segments. Specificity was rather poor in the iliac (58%) and crural (50%) region and moderate in the femoral and popliteal level (73%). The negative predictive value ranged between 78 and 91%. The grade of stenosis tend to be overestimated rather than underestimated in all levels with positive predictive values between 55 and 78%. DISCUSSIONS AND CONCLUSIONS Body-coil-based contrast-enhanced MRA has limited potential in distinguishing moderate from severe stenoses in peripheral occlusive disease. Overestimations are more common than underestimations. Both occur mainly in small-sized crural arteries but also in larger iliac arteries where vessel course in partition direction may cause inadequacy between voxel size and lumen diameter in severe stenosis.

Pulmonary sequestration: demonstration of blood supply with 2D and 3D MR angiography

Pulmonary sequestration is a relatively rare but clinically significant congenital anomaly. This disease is a spectrum of disorders involving the pulmonary airways, the arterial supply to the lungs, the lung parenchyma and its venous drainage. Traditionally, the diagnosis of pulmonary sequestration has been made definitively with arterial angiography. It is imperative for the preoperative evaluation that the arterial supply and venous drainage of the sequestered segment is identified. Several cases of MR diagnosis and preoperative evaluation of pulmonary sequestration and blood supply have been reported. In this case, MR imaging was able to provide important information about systemic blood supply via intercostal arteries and regular venous drainage. Furthermore this imaging technique revealed a second pulmonary sequestration in the dorsal phrenicocostal sinus that was not diagnosed before.

Prospective evaluation of bone marrow signal changes on magnetic resonance tomography during high-dose chemotherapy and peripheral blood stem cell transplantation in patients with breast cancer.

RATIONALE AND OBJECTIVES The authors evaluate bone marrow signal changes on magnetic resonance (MR) imaging during high-dose chemotherapy and peripheral blood stem cell transplantation (PBSCT). METHODS Fourteen patients with breast cancer without bone metastases underwent four sagittal MR imaging studies with T1-weighted, T2-weighted turbo spin-echo and inversion recovery sequences with short inversion time (STIR) of the lumbar spine: (1) during initial staging, (2) prior to high-dose chemotherapy after two cycles of induction chemotherapy, (3) early after PBSCT with a leukocyte exceeding 2000/microL, and (4) 6 to 8 weeks after PBSCT. Signal intensity ratios of averaged lumbar bone marrow to nucleus pulposus were measured and homogeneity was evaluated visually using a semiquantitative score. RESULTS Compared with the initial finding (1): Signal intensity ratios were altered significantly at (2): T1-weighted: -22% +/- 14, P < 0.001; T2-weighted: -11% +/- 11, P < 0.01; STIR: +33% +/- 31, P < 0.01; Signal intensity ratios were altered significantly at (3): T2-weighted: -23% +/- 12, P < 0.001, STIR: -22% +/- 23, P < 0.01; and Signal intensity ratios were altered significantly at (4): only STIR: -16% +/- 19, P < 0.01. Homogeneity scores decreased at (3) for T1-weighted and STIR sequences (-1.6 +/- 0.5 to -2.0 +/- 0.7, P < 0.01 and -1.0 +/- 0.5 to -1.4 +/- 0.5, P < 0.01, respectively) and at (4) for the latter sequence (-1.0 +/- 0.5 versus -1.4 +/- 0.5, P < 0.01). At (4), T1-weighted images were less homogenous than initially in 3 of 14 (21%) patients. CONCLUSIONS Magnetic resonance imaging demonstrates significant alterations of bone marrow composition during PBSCT but allows differentiation of benign therapy-related changes from those known in metastatic disease after completion of PBSCT.

PELVIC IMAGING WITH A SELENIUM-BASED DETECTOR (THORAVISION) : COMPARISON WITH SCREEN-FILM RADIOGRAPHY IN 75 PATIENTS

OBJECTIVE To evaluate whether the selenium detector (Thoravision) provides sufficient diagnostic confidence in digital pelvic imaging compared with a conventional screen-film combination. METHODS In 75 patients, pelvic imaging with conventional screen-film and isodose selenium radiography using a dedicated postprocessing mode was compared independently by three radiologists. The depiction of cortical and cancellous bone was evaluated in the iliac wings, sacral and pubic bones, acetabulum, femoral head, and trochanter. Demarcation of soft tissue was assessed in the iliac and trochanteric region. RESULTS Visualization of cortical bone and soft tissue in the iliac area as well as soft tissue and cortical and cancellous bone in the trochanteric region was significantly superior with the selenium detector. However, conventional imaging was better in the trabecular bone of the sacral region, where results with the selenium system were particularly poor. CONCLUSIONS The selenium detector (Thoravision) is advantageous in imaging soft tissue adjacent to the iliac wings and the trochanter, but results for the cancellous sacral bone are poor. Further modifications of postprocessing modes may lead to improved depiction of this critical pelvic area.