A stress MRI of the shoulder for evaluation of ligamentous stabilizers in acute and chronic acromioclavicular joint instabilities.

PURPOSE: To show the feasibility of a stress magnetic resonance imaging (MRI) as a new method for simultaneous evaluation of the morphology and the functional integrity of the acromioclavicular joint (ACJ) ligamentous stabilizers. MATERIALS AND METHODS: MRI of four volunteers, 10 patients with acute, and six with chronic ACJ injuries was performed using a 0.25 T open MRI scanner. A 2D-proton-density and a 3D-gradient-echo sequence at rest and under 6.5 kg shoulder traction were performed. Comparative measurements of the coracoclavicular and the acromioclavicular distance were performed. Additionally, the conoid and trapezoid ligament lengths were measured with multiplanar reconstructions. RESULTS: MRI at rest correctly identified tears of the coracoclavicular and the acromioclavicular ligaments in eight patients suffering acute ACJ injuries. Stress application helped to distinguish between partial and complete coracoclavicular ligament tears in two cases. Insufficiency of the ACJ ligaments was present in all acute and chronic ACJ injuries. Stress application in chronic ACJ ligaments revealed isolated insufficiency of the conoid ligament in three cases and of the trapezoid ligament in one case. Combined insufficiency was present in two cases. CONCLUSION: Stress MRI facilitates simultaneous acquisition of morphologic and functional information of the ACJ stabilizers. In acute ACJ injuries it helps to distinguish between partial and complete ligament tears. In chronic ACJ injuries it provides functional information of the ligament regrinds.

In vivo analysis of coracoclavicular ligament kinematics during shoulder abduction.

BACKGROUND: Anatomic reconstruction of the coracoclavicular ligaments for the treatment of acromioclavicular joint separations provides superior biomechanical stability compared with other procedures. Clavicular and coracoidal footprints of the conoid ligament (CL) and the trapezoid ligament (TL) are well described. So far, little is known about their kinematics and the changes of the coracoclavicular distance during shoulder abduction. HYPOTHESIS: The coracoclavicular distance along the coracoclavicular ligaments changes significantly with shoulder abduction and weightbearing. STUDY DESIGN: Descriptive laboratory study. METHODS: With use of an open magnetic resonance imaging scanner, the shoulders of 13 healthy volunteers were examined in supine and sitting positions. Three-dimensional magnetic resonance images of the shoulders were obtained in 30° increments of abduction (0°-120°). A manual segmentation of the scapula, the clavicle, and the coracoclavicular ligaments was performed. The insertion points of the coracoclavicular ligaments were identified, and automated measures along the ligamentous course were carried out. RESULTS: During transfer from the lying to sitting position, the coracoclavicular distance showed significant lengthening of 3 mm along the center of the CL, which significantly increased another 3 mm during shoulder abduction to a total lengthening of 6 mm. In the supine position, the coracoclavicular distance along the TL did not elongate significantly. In the sitting position, the distance along the medial portion of the TL shortened significantly, whereas the distance along the center portion did not elongate significantly during shoulder abduction. CONCLUSION: The distances between the coracoclavicular insertion points depend on both patient and shoulder positioning. To prevent overconstraining of the graft, the CL should be fixated during 90° to 120° of shoulder abduction in a sitting position. Isometric reconstruction of the TL can be achieved if precise fixation of the graft at the centers of the conoidal and clavicular footprints is performed.

Reducing the radiation dose for low-dose CT of the paranasal sinuses using iterative reconstruction: feasibility and image quality.

PURPOSE: To evaluate image quality of dose-reduced CT of the paranasal-sinus using an iterative reconstruction technique. METHODS: In this study 80 patients (mean age: 46.9±18 years) underwent CT of the paranasalsinus (Siemens Definition, Forchheim, Germany), with either standard settings (A: 120 kV, 60 mAs) reconstructed with conventional filtered back projection (FBP) or with tube current-time product lowering of 20%, 40% and 60% (B: 48 mAs, C: 36 mAs and D: 24 mAs) using iterative reconstruction (n=20 each). Subjective image quality was independently assessed by four blinded observers using a semiquantitative five-point grading scale (1=poor, 5=excellent). Effective dose was calculated from the dose-length product. Mann-Whitney-U-test was used for statistical analysis. RESULTS: Mean effective dose was 0.28±0.03 mSv(A), 0.23±0.02 mSv(B), 0.17±0.02 mSv(C) and 0.11±0.01 mSv(D) resulting in a maximum dose reduction of 60% with iterative reconstruction technique as compared to the standard low-dose CT. Best image quality was observed at 48 mAs (mean 4.8; p<0.05), whereas standard low-dose CT (A) and maximum dose reduced scans (D) showed no significant difference in subjective image quality (mean 4.37 (A) and 4.31 (B); p=0.72). Interobserver agreement was excellent (κ values 0.79-0.93). CONCLUSION: As compared to filtered back projection, the iterative reconstruction technique allows for significant dose reduction of up to 60% for paranasal-sinus CT without impairing the diagnostic image quality.

Bilateral contrast-enhanced MR angiography of the hand: diagnostic image quality of accelerated MRI using echo sharing with interleaved stochastic trajectories (TWIST).

OBJECTIVES: To evaluate the image quality of time-resolved contrast-enhanced MRA (tr-MRA) employing echo-sharing with stochastic trajectories for the bilateral examination of the hands. METHODS: In this institutional review-board approved study, Tr-MRA was compared with multiphasic contrast-enhanced MRA (mp-MRA) featuring sub-systolic venous compression in 20 healthy volunteers at 3.0 T using the following settings: TR/TE: 2.8/1.2 ms, flip angle: 25°, acceleration factor: 4, effective voxel size: 0.9 × 0.8 × 0.9 cm, acquisition time 4.9 s per 3D volume. RESULTS: With tr-MRA the arterial first-pass contrast agent transit is clearly seen. On average the contrast agent arrived 34 s post-injection and reached the proper digital arteries after 44 s. The mean arterio-venous window was 13 s. Bilateral contrast enhancement was asynchronous in 56-62%. On a semiquantitative scale (0 = non-sufficient to 4 = excellent) tr-MRA (mp-MRA) yielded an average ranking of 2.8-3.6 (3.1-3.8) in the greater and intermediate sized segments and 1.3-2.0 (1.6-2.3) in the proper digital arteries. CONCLUSION: Compared with established multiphasic ce-MRA, time-resolved MRA allows a four times faster acquisition. It reflects the natural haemodynamics of the hand arteries with no need for sub-systolic venous compression and may be beneficial in the detection of hand circulation disorders. Image quality is comparable to mp-MRA. In both techniques depiction of the proper digital arteries is limited.

Thoracic aorta: prospective electrocardiographically triggered CT angiography with dual-source CT--feasibility, image quality, and dose reduction.

PURPOSE: To prospectively investigate the feasibility, image quality, and radiation dose for prospective electrocardiographically (ECG) triggered sequential dual-source computed tomographic (CT) angiography of the thoracic aorta in comparison to retrospective ECG-gated helical dual-source CT angiography. MATERIALS AND METHODS: This study was approved by the institutional review board; informed consent was obtained. One hundred thirty-nine patients referred for ECG-assisted dual-source CT angiography of the thoracic aorta were prospectively enrolled. Inclusion criteria were stable sinus rhythm and heart rate of 80 beats per minute or less. Tube voltage was adjusted to body mass index (< 25.0 kg/m(2), 100 kV, n = 58; > or = 25.0 kg/m(2), 120 kV, n = 81). In both cohorts, patients were randomly assigned to prospective or retrospective ECG-assisted data acquisition. In both groups, tube current (250 mAs per rotation) was centered at 70% of the R-R cycle. The presence of motion or stair-step artifacts of the thoracic aorta was independently assessed by two readers. Effective radiation dose was calculated from the dose-length product. RESULTS: Subjective scoring of motion and stair-step artifacts was equivalent for both techniques. Scan length was not significantly different (23.8 cm +/- 2.4 [standard deviation] vs 23.7 cm +/- 2.5 for prospective and retrospective ECG-triggered CT angiography, respectively; P = .54). Scanning time was significantly longer for prospective ECG-triggered CT angiography (18.8 seconds +/- 3.4 vs 16.4 seconds +/- 3.3, P < .001). Mean estimated effective dose was significantly lower for prospective data acquisition (100 kV, 1.9 mSv +/- 0.5 vs 4.1 mSv +/- 0.7, P < .001; 120 kV, 5.3 mSv +/- 1.1 vs 9.5 mSv +/- 3.0, P < .001). CONCLUSION: Prospective ECG-gated sequential dual-source CT angiography of the thoracic aorta is feasible, despite the slightly longer acquisition time. Thus, motion-free imaging of the thoracic aorta is possible at significantly lower radiation exposure than retrospective ECG-gated helical dual-source CT angiography in certain patients with a regular heart rate.

Image analysis in time-resolved large field of view 3D MR-angiography at 3T.

PURPOSE: To qualitatively and quantitatively evaluate the image quality in accelerated time-resolved 3D contrast-enhanced MR angiography (tr-CE-MRA) at 3T. MATERIALS AND METHODS: In all, 113 MRA were performed in 107 patients on a 3T MR system after written informed consent and approval by the ethics committee. Twenty consecutive thoracic (n=87) or craniocervical (n=26) 3D data volumes were acquired. The timeframes with maximum arterial and venous contrast were determined and a total of 663 arterial and venous segments were analyzed by two blinded observers. Diagnostic image quality was graded by applying a 0 (low) to 3 (excellent) scale. Additionally, local signal-to-noise (SNR) and contrast-to-noise ratios (relative CNR) were evaluated. RESULTS: Tr-CE-MRA was successfully performed in all patients. Good to excellent image quality (2.42+/-0.31) was observed in all individuals with preserved discrimination of arteries (2.43+/-0.48) and veins (2.20+/-0.56). Minor image degradation due to artifacts (2.62+/-0.25) and constantly high vascular signal and contrast were detected. There was a significant superiority of coronal orientation during thoracic MRA (P<0.05). In 18 cases tr-CE-MRA provided additional information on vascular pathologies. CONCLUSION: Large field of view tr-CE-MRA enables constantly high-quality thoracic and craniocervical angiographies. In addition, the dynamics of tr-CE-MRA can offer additional information on vascular pathologies.

Bilateral ce-MR angiography of the hands at 3.0 T and 1.5 T: intraindividual comparison of quantitative and qualitative image parameters in healthy volunteers.

The purpose of this study was to determine the benefit of bilateral contrast-enhanced MR angiography (ce-MRA) of the hands at 3.0 Tesla (T) compared with an established 1.5-T technique in healthy volunteers. Intraindividual bilateral ce-MRA of the hands was performed at 1.5 T and 3.0 T in 14 healthy volunteers using a timed ultra-fast GRE sequence featuring parallel acquisition. The evaluation comprised measurement of the vessel signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), rating of the image quality and the assessment of artefacts and venous contamination. At 3.0 T, SNR improved up to 95% and CNR up to 129%. The image quality of the larger inflow arteries, the palm arches and common digital arteries was good or sufficient at either magnetic field strengths. However, 3.0-T MRA was clearly superior in the depiction of the digital arteries. Ce-MRA of the hand clearly profits from the use of 3.0 T. Compared with 1.5 T, a substantial increase of CNR is found resulting in a significantly better delineation of the small digital arteries. Saturation affects more the SNR of the perivascular tissue than the contrast-enhanced blood, and thus leads to a marked increase of CNR at 3.0.

Visualization of iliac and proximal femoral artery hemodynamics using time-resolved 3D phase contrast MRI at 3T.

PURPOSE: To demonstrate the feasibility of time-resolved 3D MR velocity mapping at 3 Tesla for the visualization of vascular hemodynamics in normal iliac and femoral arteries. MATERIALS AND METHODS: Electrocardiographically (ECG) synchronized three-dimensional (3D) CINE phase-contrast MRI with three-directional flow encoding was adapted to analyze flow in peripheral arteries at 3T. Visualization of peripheral arterial hemodynamics within the acquired data volume included 3D streamlines and time-resolved 3D particle traces within the major vessels and localized analysis of flow profiles using 2D-vector graphs. Data was visually compared to results from color-coded duplex ultrasound (US). RESULTS: Global and detailed local blood flow characteristics were successfully analyzed in all subjects. In agreement with US findings, normal laminar flow patterns without flow acceleration or disturbances were visualized in all healthy individuals. In an exemplary patient measurement multiple segmental flow accelerations could be demonstrated. MRI additionally revealed complex helical flow alterations distal to a moderate stenosis. CONCLUSION: Due to the full spatial and temporal coverage of the arteries of interest, 3D CINE phase contrast MRI at 3T is a promising tool for the evaluation of vascular hemodynamics in peripheral arteries. Future methodological improvements will be directed to improve spatial and temporal resolution as well as quantitative data analysis. Moreover, the technique will have to be evaluated in patients in comparison to standard diagnostic tools.

A multicenter, site-independent, blinded study to compare the diagnostic accuracy of contrast-enhanced magnetic resonance angiography using 1.0M gadobutrol (Gadovist) to intraarterial digital subtraction angiography in body arteries.

PURPOSE: Prospective evaluation of diagnostic accuracy of single field-of-view contrast-enhanced MR Angiography (ceMRA) with 1.0M gadobutrol compared to intraarterial DSA in body arteries. MATERIALS AND METHODS: In an European multicenter study 179 patients underwent ceMRA and DSA. For each indication five prospectively defined vessel segments were evaluated by local investigators onsite and by three site-independent blinded readers (BR) independently. RESULTS: The agreement between ceMRA and DSA diagnosis was statistically significant in the onsite (96.6%) and blinded reader (86.6-90.2%) evaluation. Sensitivity, specificity, accuracy, positive (PPV) and negative predictive values (NPV) for detection of relevant stenosis (>50%) were calculated for the right and left internal carotid arteries, and common and external iliac arteries: Sensitivity was 95-98% (onsite) and 76-96% (BR), specificity 94-96% (onsite) and 86-94% (BR), accuracy 96% (onsite) and 87-93% (BR), NPV 98-99% (onsite) and 84-98% (BR), and PPV 79-93% (onsite) and 44-91% (BR), respectively. CONCLUSION: CeMRA of body arteries using 1.0M gadobutrol provides diagnostic information comparable to intraarterial DSA.

Accelerated time-resolved 3D contrast-enhanced MR angiography at 3T: clinical experience in 31 patients.

PURPOSE: To evaluate whether time-resolved 3D MR-angiography at 3T with a net acceleration factor of eight is applicable in clinical routine and to evaluate whether good image quality and a low artifact level can be achieved with a temporal update rate that allows for additional information on pathologies. MATERIALS AND METHODS: Thirty-one consecutive patients underwent time-resolved 3D contrast-enhanced MR-angiography on a 3T system. Imaging consisted of accelerated 3D gradient echo sequences combining parallel imaging with an acceleration factor of four, partial Fourier acquisition along phase and slice encoding direction, and twofold temporal acceleration using view sharing. Data volumes representing the arterial and venous contrast phases were independently evaluated by two experienced radiologists by grading of image quality and artifact level on a 0-3 scale. RESULTS: Time-resolved MR-angiography was successfully performed in all subjects without the need for contrast agent bolus timing. Excellent arterial (average score = 2.65 +/- 0.32) and good venous (average score = 2.56 +/- 0.28) diagnostic image quality and little image degrading due to artifacts (average score = 2.20 +/- 0.16) were confirmed by both independent readers (agreement in 65.2% of all evaluations). In 14 patients vascular pathologies were identified in the arterial phases. In eight examinations temporal resolution and depiction of contrast agent dynamics provided additional information about pathology. DISCUSSION: Without the necessity for additional bolus timing, time-resolved 3D contrast-enhanced MR-angiography with imaging acceleration along both the spatial encoding direction and temporal domain revealed excellent diagnostic image quality in neurovascular and thoracic imaging. Despite the limited spatial resolution as compared to high-resolution imaging of the carotid artery bifurcation, the results demonstrate the applicability of contrast-enhanced MR-angiography in thoracic and abdominal MRA as well as cervical imaging with a temporal update rate allowing for additional information on pathologies. Future studies may include an evaluation of optimal trade-offs between spatial and temporal resolution, different acceleration factors and a comparison to the gold-standard for accuracy.

Comparison of the detectability of high- and low-contrast details on a TFT screen and a CRT screen designed for radiologic diagnosis.

RATIONALE AND OBJECTIVES: To evaluate the detection rate of fine details of a new thin-film transistor (TFT) grayscale monitor designed for radiologic diagnosis, compared with a type of cathode ray tube (CRT) screen used routinely for diagnostic radiology. METHODS: Fifteen radiographs of a statistical phantom presenting low- and high-contrast details were obtained and read out with an Agfa ADC compact storage phosphor system. Each radiograph presented 60 high-density (high-contrast) and 60 low-density (low-contrast) test bodies. Approximately half the test bodies contained holes with different diameters. Observers were asked to detect the presence or absence of a hole in the test body on a 5-point confidence range. The total of 1800 test bodies was reviewed by 5 radiologists on the TFT monitor (20.8 inches; 1536 x 2048 pixels; maximum luminance, 650 cd/m2; contrast, 600:1) and the CRT monitor (21 inches; P45 Phosphor; 2048 x 2560 pixels operated at 1728 x 2304 pixels; maximum luminance, 600 cd/m2; contrast, 300:1). The data were analyzed by receiver-operator characteristic analysis. RESULTS: For high-contrast details, the mean area under the curve rated 0.9336 for the TFT monitor and 0.9312 for the CRT monitor. For low-contrast details, the mean area under the curve rated 0.9189 for the TFT monitor and 0.9224 for the CRT monitor. At P

Computed tomography in gastrointestinal stromal tumors.

The aim of this study was to define the imaging characteristics of primary and recurrent gastrointestinal stromal tumors (GIST) in computed tomography with respect to the tumor size. Computed tomography was performed in 35 patients with histologically confirmed gastrointestinal stromal tumors and analyzed retrospectively by two experienced and independent radiologist. The following morphologic tumor characteristics of primary ( n=20) and ( n=16) recurrent tumors were evaluated according to tumor size, shape, homogeneity, density compared with liver, contrast enhancement, presence of calcifications, ulcerations, fistula or distant metastases and the anatomical relationship to the intestinal wall, and the infiltration of adjacent visceral organs. Small GIST (<5 cm) showed a sharp tumor margin with homogeneous density and structure on unenhanced and contrast-enhanced images, and were characterized by an intraluminal tumor growth. Intermediate sized GIST (>5-10 cm) demonstrated an irregular shape, inhomogeneous density on unenhanced and contrast-enhanced images, a combined intra- and extraluminal tumor growth with aggressive findings, and infiltration of adjacent organs in 9 primary diagnosed and 2 recurrent tumors. Large GIST (>10 cm), which were observed in 8 primary tumors and 11 recurrent tumors, showed an irregular margin with inhomogeneous density and aggressive findings, and were characterized by signs of malignancy such as distant and peritoneal metastases. Small recurrent tumors had a similar appearance as compared with large primary tumors. Computed tomography gives additional information with respect to the relationship of gastrointestinal stromal tumor to the gastrointestinal wall and surrounding organs, and it detects distant metastasis. Primary and recurrent GIST demonstrate characteristic CT imaging features which are related to tumor size. Aggressive findings and signs of malignancy are found in larger tumors and in recurrent disease. Computed tomography is useful in detection and characterization of primary and recurrent tumors with regard to tumor growth pattern, tumor size, and varied appearances of gastrointestinal stromal tumors, and indirectly gives hints regarding dignity and therefore prognostic outcome.

Evaluation of Lossy data compression of chest X-rays: a receiver operating characteristic study.

RATIONALE AND OBJECTIVES: To evaluate the quality of chest radiographs after 32:1 compression/decompression with different image compression algorithms. METHODS: Ten digital (Thoravison) radiographs of an anthropomorphic chest phantom with superimposed simulated nodular lesions (NL) and linear reticular lesions (LL) were obtained. Each radiograph was subdivided into 15 fields; they contained the lesions with a probability of 0.5. The radiographs were compressed and decompressed by using JPEG, fractal and wavelet algorithms at a compression rate of 32:1. Five radiologists evaluated the images. Data were analyzed with the receiver operating characteristic (ROC) method (comparison of area under curve). RESULTS: At 32:1 JPEG or wavelet compression, no statistically significant difference was observed for both NL and LL when compared with the original images. The fractal algorithm performed significantly lower for both NL and LL when compared with the original radiographs. CONCLUSION: The JPEG and wavelet image compression does not result in loss of relevant information for chest x-rays at a compression rate of 32:1.

Pancreatico-mediastinal fistula with a mediastinal mass lesion demonstrated by MR imaging.

Internal pancreatic fistulas are uncommon but well-recognized complications of inflammatory pancreatic disease. A case of a pancreatico-mediastinal fistula with a mediastinal mass lesion in a patient with a documented history of chronic alcohol consumption and previous episodes of acute pancreatitis is described. Since the clinical symptomatology was dominated by pulmonary complaints, magnetic resonance (MR) imaging using a breathhold coronal T2-weighted sequence with spectral fat saturation was essential in clarifying this difficult and rare pathology. Furthermore, the depiction of a fistulous tract between a mediastinal mass lesion and the retroperitoneum posterior to the pancreas, i.e., a pancreatico-mediastinal fistula by MR imaging has not been previously reported, to the best of our knowledge.

Assessment of pulmonary perfusion with ultrafast projection magnetic resonance angiography in comparison with lung perfusion scintigraphy in patients with malignant stenosis.

RATIONALE AND OBJECTIVE: The aim of this study was to demonstrate and measure perfusion deficits caused by central bronchogenic carcinoma and to compare magnetic resonance angiography (MRA) perfusion data with data of perfusion scintigraphy. The diagnostic value of 2D MRA in detection of malignant pulmonary artery stenosis in comparison with conventional DSA was investigated. MATERIALS AND METHODS: Eighteen patients were included in the study. MRA, conventional pulmonary angiograms, and pulmonary perfusion scintigrams were performed. MRA and DSA were compared and MR pulmonary perfusion data were assessed and compared with scintigraphical data. RESULTS: Perfusion defect could be demonstrated and localized in all patients. A quantitative perfusion deficit and a side dependent perfusion ratio could be evaluated. There was statistically significant correlation between MR perfusion and scintigraphically acquired data. 2D MRA showed a high correlation for detection and grading of stenosis compared with angiograms. CONCLUSIONS: Pulmonary perfusion could be demonstrated by using an ultrafast 2D projection MR DSA sequence. This technique allows measurement and quantification of pulmonary perfusion abnormalities in patients with malignant stenosis with statistically significant correlation to perfusion scintigraphy. The diagnostic potency in the evaluation of malignant pulmonary artery stenosis compared with conventional DSA could be shown.

Magnetic resonance imaging for supraspinatus muscle atrophy after cuff repair.

Between 1998 to 2000, the shoulders of 17 patients with rotator cuff tears were examined using magnetic resonance imaging preoperatively, and 6 and 12 months after open surgical repair. To assess the course of the supraspinatus muscle atrophy, the easily reproducible magnetic resonance imaging parameters occupation ratio and tangent sign in the Y-shaped view of the supraspinous fossa were evaluated and compared with the clinical examination. Occupation ratio is a quantitative parameter that reflects the area ratio, expressed as a percentage of the supraspinatus muscle belly to the supraspinous fossa. The tangent sign is a qualitative parameter that represents a line connecting the coracoid process and the apex of the scapular spine. Occupation ratio and tangent sign are reliable diagnostic tools in magnetic resonance imaging assessment of supraspinatus muscle atrophy. The sensitivity of the magnetic resonance imaging parameter occupation ratio is 75% and the specificity is 85%. The imaging parameter tangent sign has a sensitivity of 100% and a specificity of 85%. There is a significant relationship between occupation ratio, tangent sign, and improvement of strength and mobility registered in the score of Constant and Murley 12 months after surgery.

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.

Comparative diagnostic value and therapeutic relevance of magnetic resonance imaging and bone marrow scintigraphy in patients with metastatic solid tumors of the axial skeleton.

PURPOSE: To evaluate the comparative impact of magnetic resonance imaging (MRI) and bone marrow scintigraphy (BMS) in bone marrow metastases of solid tumors. METHODS: In 20 patients with solid tumors MRI of the axial skeleton and whole-body BMS were retrospectively reviewed. Detectability of metastases, extent of disease and therapeutic implications were assessed. RESULTS: In 15/20 (75%) patients MRI and BMS concordantly revealed bone marrow metastases of the axial skeleton. In nine of these 15 patients (60%) MRI showed more metastases. Local radiotherapy or surgery was performed in seven of these cases (78%). BMS detected additional metastases of the appendicular skeleton in 8/15 (53%) patients. In 4/20 cases (20%) the imaging findings were discordant. In three patients with degenerative changes (n=2) or lipoma (n=1) BMS was false positive. In another patient BMS failed to detect metastases proven by MRI and clinical follow-up resulting in subsequent radiation therapy. One patient had normal bone marrow. CONCLUSION: MRI appears to be more sensitive and specific in the detection of bone marrow metastases in the axial skeleton and is of clinical importance for subsequent local therapy.

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.