A therapeutic option in nutcracker syndrome and ovarian vein insufficiency.

OBJECTIVES: The nutcracker syndrome (NS) may lead to insufficient perirenal collaterals as well as incompetence of the left ovarian vein with consecutive ovarian vein insufficiency. METHODS: A female patient with NS and severe genital varicosis was treated with dilation of the renal vein and coiling of a left perirenal collateral vein feeding an insufficient left ovarian vein (LOV) with pelvic vein varicosity. RESULTS: In re-evaluation 18 month later with left renal vein (LRV) and LOV phlebography, a widely patent LRV was found. The embolized LRV to LOV collateral was occluded. However, left hypogastric phlebography showed incompetent branches of the left hypogastric vein feeding the genital varicose veins. These were successfully embolized with coils and the genital varicosity decreased on follow-up. CONCLUSIONS: In our patient a combined therapeutic approach with balloon dilation of the NS and embolization of the genital varicose veins by left hypogastric vein coil was performed.

Pitfalls in MR morphology of the sterno-costo-clavicular region using whole-body MRI.

AIM: To analyse the imaging findings at the sterno-costo-clavicular (SCC) joint region using whole-body (WB) magnetic resonance imaging (MRI) in healthy individuals to minimize misinterpretation as changes due to spondyloarthritis (SpA). MATERIALS AND METHODS: As part of a cross-sectional study of 122 SpA patients, 75 healthy individuals (42/33 males/females; median age 30.3 years; range 17.7-63.8 years) were scanned using sagittal and coronal WB short tau inversion recovery (STIR) and T1-weighted MRI sequences. The SCC region was analysed independently by seven readers for bone marrow oedema (BMO), erosions, subchondral fat signal intensity (FSI), and joint fluid accumulation. RESULTS: SCC changes simulating inflammation were reported by four or more of the seven readers in 15 (20%) healthy individuals (12 male/three female; median age 32.1 years; range 20.2-48 years). Thirteen individuals (17%) had changes at the manubriosternal joint (MSJ); five had BMO, one BMO + erosion, four erosion, two erosion + FSI, and one FSI only. Changes at the sternoclavicular joint occurred in three individuals (4%) encompassing erosion, erosion + FSI + BMO, and joint fluid accumulation, respectively. One patient had both MSJ and sternoclavicular joint changes. CONCLUSIONS: Findings mimicking inflammatory changes occurred in healthy individuals, particularly in the MSJ. Awareness of this is important in recognition of SCC inflammation in SpA.

[How to Read a Chest-X-ray?]. / Wie lese ich eine Thoraxaufnahme?

Only a standartized, systematic approach allows a complete review of a chest x-ray and the collection of all relevant informations. In detail, alterations of the following structures should be sought: soft tissue, bones, pleura, mediastinum, lung, heart, pulmonary circulation and hili. Technical factors and the position of the patient should also be considered.

Quantitative d-dimer levels and the extent of venous thromboembolism in CT angiography and lower limb ultrasonography.

BACKGROUND: We evaluated the diagnostic yield of multidetector-row CT angiography and determined the clot burden within pulmonary vasculature as a measure of pulmonary embolism (PE) severity at different d-dimer levels and pretest clinical probabilities. PATIENTS AND METHODS: 254 consecutive patients referred to CT pulmonary angiography for suspected PE after d-dimer testing were grouped into clinical probability classes using Wells' score, and the frequency of PE was determined. A score representing clot burden within pulmonary vasculature was calculated from the number of obstructed segmental arteries in CT scans in a partly differing group of 96 PE positive patients. RESULTS: The prevalence of PE increases with the d-dimer level (7% at d-dimer levels of 0.5-1 microg/ml, reaching 90% at d-dimer levels > 9 microg/ml; p < 0.001). D-dimer levels above 4 microg/ml are associated with a significantly higher clot burden in pulmonary arteries (median score 11 versus 5, and 53% versus 16% of patients in the subgroup with a score > 10 points; p < 0.001), and thrombus in a main pulmonary artery was detected more frequently (37% versus 9%, p = 0.003). Similar results were obtained for distal versus proximal deep venous thromboses, detected by ultrasonography of the lower limb in a separate group of 44 patients. CONCLUSIONS: High d-dimer levels are associated with an increased prevalence of CT radiographic findings indicating extended clinically severe PE or lower limb venous thrombosis.

Hepatic fascioliasis: report of two cases.

Two cases of hepatic fascioliasis with characteristic features in US examinations and CT scans are presented. In both modalities they show tunnel-like branching and clustered areas of low echogenicity/density, which reach subcapsular regions. These cases are presented to recall the imaging features in hepatic fascioliasis especially outside endemic regions. Not only CT but also US is able to detect these characteristic lesions, which may help to make the diagnosis of hepatic fascioliasis in patients with clinical symptoms suggestive of parasitic disease.

Changes in cross-sectional measurements of the spinal canal and intervertebral foramina as a function of body position: in vivo studies on an open-configuration MR system.

OBJECTIVE: The purpose of this study was to evaluate physiologic changes of the cross-sectional area of the spinal canal and neural foramina in young asymptomatic volunteers. SUBJECTS AND METHODS: Twelve asymptomatic volunteers were examined in a 0.5-T open-configuration MR system. T2-weighted fast spin-echo sequences were obtained in upright neutral, upright flexed, upright extended, and supine extended positions. The cross-sectional area of the spinal canal and the thickness of the ligamentum flavum were measured on angled axial images at the L4-L5 level. The anteroposterior diameter of the spinal canal and cross-sectional areas of the neural foramina were measured on sagittal images from L1 to S1. RESULTS: At disk level, the cross-sectional area of the spinal canal varied significantly between body positions, most notably between the upright flexed (mean, 268 mm2) and the upright extended (mean, 224 mm2) positions (p < .0001). The maximum thickness of the ligamenta flava increased in the extended positions (p < .0001). The cross-sectional area of the neural foramina underwent position-dependent variations of as much as 44.4%. The smallest cross-sectional areas were found in the extended positions. CONCLUSION: In asymptomatic volunteers, MR imaging is able to show position-dependent changes in the cross-sectional areas of the spinal canal and the intervertebral foramina. The extended positions best reveal important findings.

MRI of the foot and ankle: diagnostic performance and patient acceptance of a dedicated low field MR scanner.

The objective of this study was to compare image quality and patient acceptance of a dedicated .2-T MR system and a 1.0-T whole body system. Forty-one consecutive patients referred for MRI of the foot or ankle were prospectively examined with a dedicated .2-T low field system and a 1.0-T whole body system. Images were evaluated qualitatively by two observers and quantitatively using signal-difference-to-noise ratios. The patients were interviewed with respect to positioning, examination time, noise, claustrophobia, confidence in the diagnosis, and willingness to repeat the examination, using a questionnaire. The qualitative score was significantly higher for the 1.0-T system (2.6 vs 2.2 for reader 1 [P = .008] and 2.6 vs 1.7 for reader 2 [P < .0001]), respectively). The signal-difference-to-noise ratios were also superior for the 1.0-T MR system (2.96 vs .88, P < .0001). However, 96% of the lesions visualized at 1.0 T were also detected with the low field system. Patient acceptance was significantly better for the 1.0-T MR scanner (48.6 vs 43.9, P = .007). Image quality of the dedicated low field system was inferior to the 1.0-T system using objective parameters, and patients did not prefer the low field system. Although only 4% of lesions were missed in this series, the low field MR system can only be recommended when funding is limited and the available space is limited.

Lumbar spine: quantitative and qualitative assessment of positional (upright flexion and extension) MR imaging and myelography.

PURPOSE: To compare measurements of the sagittal diameter of the lumbar dural sac obtained at positional magnetic resonance (MR) imaging and at functional myelography and to assess the influence of various body positions on the dural sac and the intervertebral foramina. MATERIALS AND METHODS: Thirty consecutive patients referred for lumbar myelography were examined with an open 0.5-T MR imager, Sagittal T2-weighted fast spin-echo images were acquired with patients in the supine, upright flexion, and upright extension positions. The midsagittal diameter of the dural sac was measured at the level of the disks on MR images and myelograms. Foraminal sizes on the MR images were scored independently by two observers. RESULTS: Correlation between MR imaging and myelographic measurements was high (r = .81-.97). A small but statistically significant positional dependence of the dural sac diameter was found in the lower lumbar spine. Position-dependent differences in foraminal scores were uncommon. CONCLUSION: Quantitative assessment of sagittal dural sac diameters is comparable between lumbar myelography and positional MR imaging. In a selected patient population, only small changes in the sagittal diameter of the dural sac and foraminal size can be expected between various body positions, and the information gained in addition to that from standard MR imaging is limited [corrected].

Differentiation of necrotizing fasciitis and cellulitis using MR imaging.

OBJECTIVE: This study was performed to evaluate the diagnostic value of MR imaging in differentiating necrotizing fasciitis from cellulitis. MATERIALS AND METHODS: Spin-echo T1-weighted, T2-weighted, and contrast-enhanced T1-weighted spin-echo sequences were performed in 15 patients with clinically suspected necrotizing fasciitis. In two other patients, only unenhanced imaging was performed. The MR imaging results were correlated with the surgical findings in 11 cases, with autopsy in one case, and with the clinical outcome in five cases. RESULTS: Cellulitis was diagnosed when subcutaneous thickening with fluid collections was revealed on T2-weighted images and when subcutaneous tissue or superficial fascia or both showed contrast enhancement. For the diagnosis of necrotizing fasciitis, imaging revealed additional involvement of deep fasciae with fluid collections, thickening, and enhancement after contrast administration. According to these criteria, we found 11 cases of necrotizing fasciitis and six of cellulitis. MR imaging identified all 11 cases of necrotizing fasciitis correctly when compared with the surgical findings. One false-positive case of cellulitis was overstaged and was thought to be necrotizing fasciitis. Contrast-enhanced T1-weighted sequences delineated abscesses and areas of necrosis more clearly than T2-weighted sequences did, but showed no additional lesions. CONCLUSION: When no deep fascial involvement is revealed with MR imaging, necrotizing fasciitis can be excluded. However, because its sensitivity exceeds its specificity, MR imaging tends to overestimate the extent of deep fascial involvement. Therefore, the therapeutic regimen should be based on a combination of clinical findings and MR imaging.

Improved growth with bioabsorbable sutures in both high- and low-pressure zones.

BACKGROUND: Compromised growth after operation remains a significant problem in the cardiovascular field. Some benefit of absorbable suture materials has been demonstrated for arterial anastomoses. However, for the low-pressure zone, few data are available. METHODS: To assess growth in high- versus low-pressure zones we transected the abdominal aorta (high-pressure zone) as well as the inferior vena cava (low-pressure zone) in 10 young mongrel dogs using for reanastomosis 7-0 nonabsorbable versus absorbable running sutures in random order. RESULTS: All animals survived and were evaluated over 12 months including body weight (gain, 212% +/- 45% for nonabsorbable versus 218% +/- 8% for absorbable; not significant), angiography, and, after elective sacrifice, detailed studies of aorta and vena cava. Systematic complication of angiographic data at 12 months showed at the suture level an area of 13.8 mm2 for nonabsorbable versus 24.3 +/- 14.4 mm2 for absorbable sutures in the high-pressure zone as compared with 12.9 +/- 4.9 mm2 for nonabsorbable versus 25.3 +/- 15.4 mm2 for absorbable sutures in the low-pressure zone. Residual lumen, calculated as a function of the area above and below the suture, accounted for 35% +/- 10% for nonabsorbable versus 92% +/- 12% for absorbable sutures (p < 0.001) in the high-pressure zone as compared with 37% +/- 13% for nonabsorbable versus 75% +/- 15% for absorbable sutures (p < 0.003) in the low-pressure zone (high versus low, not significant). Poststenotic dilatation accounted for 199% +/- 22% for nonabsorbable versus 126% +/- 43% for absorbable sutures (p < 0.01) in the high-pressure zone. In the low-pressure zone, poststenotic dilatation remained below the inflow area, and the residual poststenotic lumen accounted for 52% +/- 14% for nonabsorbable versus 77% +/- 16% for absorbable sutures (p < 0.004). Macroscopic, light, and scanning electron microscopic studies confirmed different growth patterns in high- versus low-pressure zones. CONCLUSIONS: Aortic narrowing resulted in poststenotic dilatation and unrestricted outflow path (hourglass-type stenosis). Caval narrowing was followed by restriction of poststenotic outflow path (funnel-type stenosis). Absorbable suture material allows for superior growth in both high- and low-pressure zones.

MR relaxation times in human brain: measurement at 4 T.

PURPOSE: To determine the values for relaxation times in human brain for magnetic resonance (MR) imaging at 4 T. MATERIALS AND METHODS: T1 measurements were made with a progressive saturation sequence, an implementation of the Look-Locker sequence, and an inversion-recovery (IR) interleaved echo-planar imaging (IEPI) sequence. T2 measurements were made with a standard spin-echo (SE) sequence and an SE IEPI sequence. RESULTS: The T1 measurements yielded values of 1,724 msec +/- 51 for gray matter, 1,043 msec +/- 27 for white matter, and 4,550 msec +/- 800 msec for cerebrospinal fluid. The deep gray matter regions had T1 values of 1,458 +/- 38 (caudate nucleus) and 1,372 +/- 60 (putamen). The T2 measurements yielded results of 63 msec +/- 6.2 for gray matter and 49.8 msec +/- 2.2 for white matter. CONCLUSION: The T1 values measured at 4 T show a higher value than predicted from extrapolation at lower field strengths. The T2 measurements showed a slight decrease in values over those measured at lower-field strength. The gain in signal-to-noise ratio from the higher field strength may be substantially offset by these altered relaxation time values to a degree that is sequence dependent.

MR imaging contrast in human brain tissue: assessment and optimization at 4 T.

PURPOSE: To evaluate multiple magnetic resonance (MR) imaging sequences for their ability to provide T1 and T2-weighted images at a field strength of 4 T, and to validate previously obtained relaxation time measurements. MATERIALS AND METHODS: Different spin-echo, inversion-recovery (IR), gradient-recalled acquisition in the steady state (GRASS), and magnetization transfer contrast-enhanced GRASS sequences were evaluated in a single section, each in at least four volunteers. Also, interleaved echo-planar imaging (IEPI) and interleaved gradient-recalled echo (IGRE) sequences were analyzed and compared with standard sequences. RESULTS: Predicted contrast behavior, according to MR relaxation time measurements, was found to agree well with that of the validation experiments. Fair T1 contrast can be achieved on MR images at 4 T, contrary to early predictions. Under other conditions, however, such as partially spin-density-weighted parameters, lower contrast is observed at the high field strength when compared with conventional field strengths. CONCLUSION: The longer T1 values at higher field strengths have a substantial effect on image contrast. Depending on the sequence and parameters chosen, good image contrast can be realized at 4 T. IEPI and hybrid IR IGRE sequences are useful in shortening the prolonged examination times owing to the longer T1 values at higher field strengths.

Evaluation of methemoglobin as an autologous intravascular MRI contrast agent.

Methemoglobin (MetHb) was evaluated as an intravascular paramagnetic contrast agent. Methemoglobin formation was induced by 4-dimethylaminophenol (4-DMAP), causing a reduction in blood T2* in vitro. The 4-DMAP generated metHb with a time constant of 62 s. A 4-DMAP bolus did not decrease measurably the signal intensity in the in vivo rabbit kidney in the first pass. At steady state, a MetHb concentration of 24.8 +/- 2.3% resulted in a signal decrease of 9.2 +/- 2.6% in the kidney. Methemoglobin is an effective vascular T2* relaxation agent, but the formation of MetHb by 4-DMAP is too slow for first-pass imaging. A more effective conversion agent resulting in a bolus of at least 25% MetHb within 5 s would result in a detectable first-pass signal and a viable contrast technique.

The evaluation of dielectric resonators containing H2O or D2O as RF coils for high-field MR imaging and spectroscopy.

Electromagnetic resonators consisting of low-loss dielectric material and/or metallic boundaries are widely used in microwave technologies. These dielectric resonators usually have high Q factors and well-defined field distributions. Magnetic resonance imaging was shown as a way of visualizing the magnetic field distribution of the resonant modes of these resonators, if the dielectric body contains NMR sensitive nuclei. Dielectric resonators have also been proposed as RF coils for magnetic resonance experiments. The feasibility of this idea in high-field MR is discussed here. Specifically, the dielectric resonances of cylindrical water columns were characterized at 170.7 MHz (4 T 1H Larmor frequency), and evaluated as NMR transmit and receive coils. The dielectric resonance of a cylindrical volume of D2O was used to image a hand at 170.7 MHz. This study demonstrated that MRI is an effective way of visualizing the magnetic field in dielectric structures such as a water cylinder, and can potentially be generalized to solid-state dielectric devices. The possible applications of dielectric resonators other than simple cylindrical volumes in MRI and MR solution spectroscopy at high field strengths are also discussed.

Radiofrequency shielding of surface coils at 4.0 T.

Because radiation loss associated with a radiofrequency (RF) coil increases as roughly the fourth power of the frequency, this loss mechanism may become important in high-field studies above 2.0 T. In this study, the contribution of radiation losses at 4.0 T were determined in a rectangular surface coil using an RF shield to modify the radiation losses. The effect of this shield was determined on coil Q, B1 distribution, and signal to noise as a function of distance between the coil and the shield. Phantoms and human tissue were evaluated to characterize the loss mechanisms. The results demonstrate a large radiation loss in the unshielded surface coil. However, the radiation losses in vivo were not dominant owing to a large inductive loss occurring from dielectric currents in the body at 170 MHz.

[Rare association of a coronary fistula with a fusiform aneurysm of the superior vena cava: diagnosis via transesophageal echocardiography and MRI]. / Seltene Assoziation einer Koronarfistel mit einem fusiformen Aneurysma der Vena cava superior: Diagnose mittels transösophagealer Echokardiographie und MRI.

A congenital fistula of the left circumflex coronary artery with large aneurysmal sacculations and drainage into the vena cava superior is reported in an asymptomatic black adult female. An indicator dilution curve excluded a significant left-to-right shunt. In addition, the patient had a large fusiform aneurysm of the superior vena cava with maximal extension in the anterior upper mediastinum. Transesophageal Doppler echocardiography and magnetic resonance imaging were complementary diagnostic tools, the first for clearly visualizing coronary anatomy and shunt, the second for accurate imaging of the aneurysmal vena cava superior in the upper mediastinum.

Musculoskeletal MR imaging at 4 T and at 1.5 T: comparison of relaxation times and image contrast.

PURPOSE: To evaluate the relaxation time-based contrast between the main tissues of the musculoskeletal system as measured in the human knee with magnetic resonance imaging at 4 T and 1.5 T. MATERIALS AND METHODS: Five volunteers underwent 4-T and 1.5-T imaging. Inversion-recovery series were used to measure T1 values, and T2 values were measured with a spin-echo sequence. RESULTS: T1 values increased in all tissues with 4-T imaging. Values increased in muscle from 1 to 1.8 seconds, in fat from 0.3 to 0.4 seconds, and in cartilage from 0.8 to 1.5 seconds. T2 values were 10%-20% shorter in all tissues at 4 T. CONCLUSION: Advantages of 4-T imaging compared with 1.5-T imaging include a higher signal-to-noise ratio and an improved signal difference-to-noise ratio. However, any improvement in signal-to-noise ratio at high field strengths can partially be reduced by the increase in the T1 value. The slightly shorter T2 values at 4 T do not affect image contrast.

Single-shot versus interleaved echo-planar MR imaging: application to visualization of cardiac valve leaflets.

Visualization of the cardiac valves with standard magnetic resonance (MR) imaging is not adequate because of long acquisition times. Echo-planar imaging (EPI) can, however, be performed with a temporal resolution (30-50 msec) comparable to that of echocardiography. The authors evaluated the feasibility of real-time imaging of cardiac valve motion with ultrafast MR techniques. Eight healthy volunteers and three patients with mitral stenosis and regurgitation were studied with a 1.5-T whole-body imager. Two different EPI sequences were assessed: a standard single-shot gradient-echo EPI (GEPI) sequence and a fast imaging technique based on multiple-shot EPI with interleaved k-space acquisition (IGEPI). Fat-suppressed images with an in-plane resolution of 3.7 x 3.7 mm were obtained equally spaced through the cardiac cycle. Half-k-space acquisition was used. Morphologic evaluation was superior with IGEPI, owing to the better intracavitary signal homogeneity (P < .01), and the mitral valve leaflets were easier to identify on systolic images. IGEPI provided adequate valve visibility in all three patients.

Differences in biodistribution of the anti-(carcinoembryonic antigen) murine monoclonal antibody CE-25, its F(ab')2 fragment and its intact mainly human chimeric form CE 4-8-13. Dependence on tumour size and amount of antibody injected.

The effect of the size of the tumour and the amount of antibody injected on the biodistribution of a family of radioiodinated antibodies was studied. The intact mouse anti-(carcinoembryonic antigen) (anti-CEA) monoclonal antibody CE-25, its F(ab')2 fragment and the intact human-mouse chimeric from CE 4-8-13 were evaluated in a model system using the human CEA-producing colon xenograft T 380 grown in nude mice. The relative retention (the percentage of the injected dose per gram of tissue), of mouse mAb and F(ab')2 in tumour and most normal tissues 1 day after injection was independent of the antibody dose; after 4 days the mAb values increased with increasing antibody dose. The relative retention of chimeric mAb increased with increasing antibody dose 1 day after injection and also slightly after 4 days. The relative retention in tumour tissue was lower in bigger xenografts for all antibodies. The relative retention of mouse mAb in small tumours increased from day 1 to day 4; for chimeric mAb this value decreased. In normal tissues the relative retention of mouse mAb decreased from day 1 to day 4, but the relative retention of chimeric mAb in normal tissue dropped rapidly and changed little afterwards. Thus the biokinetics of antibodies is "species"-dependent: foreign, mainly human, chimeric antibody clears faster from normal mouse tissue than mouse antibody and reaches lower concentrations.

Normal heart: evaluation with echo-planar MR imaging.

PURPOSE: To evaluate the appearance of the heart on spin-echo (SE) and gradient-echo (GRE) echo-planar magnetic resonance (MR) images. MATERIALS AND METHODS: Nine healthy volunteers were examined with an MR imager with transaxial echo-planar imaging (EPI) capabilities. SE EPI and GRE EPI sequences were used. Full k-space signal was obtained with readout time of 40 msec per image, and total image acquisition time was 72 and 52 msec, respectively, for SE EPI and GRE EPI. RESULTS: Delineation of cardiac structures was superior with SE EPI, reflective of significantly higher contrast between myocardial and intraluminal signal intensity (SI) (P < .001). The higher (P < .01) and more homogeneous (P < .001) intraluminal SI with GRE EPI allowed better assessment of intracardiac flow. Septal SI was significantly higher for GRE EPI (P < .01), but signal homogeneity was similar for both sequences (P > .2). CONCLUSION: Diagnostic images of the heart were obtained with both SE EPI and GRE EPI. GRE EPI is more suitable for flow studies because of the higher and more homogeneous intravascular SI.