Stefan Duewell

Is Impingement the Cause of Jumper’s Knee? Dynamic and Static Magnetic Resonance Imaging of Patellar Tendinitis in an Open-Configuration System

Background Chronic overload is considered the main cause of patellar tendinitis, but it has been postulated that impingement of the inferior patellar pole against the patellar tendon during knee flexion could be responsible. Hypothesis The role of the patellar pole in patellar tendinitis can be determined by dynamic magnetic resonance imaging. Study Design Case-control study. Methods We compared 19 knees with patellar tendinitis and 32 asymptomatic knees of age-matched subjects using an open-configuration magnetic resonance imaging system. Dynamic sagittal images were obtained from full extension to 100° of flexion with and without activation of the quadriceps muscle. The following measurements were made from the images: tendon-patella angle, anteroposterior diameter of the tendon, signal difference-to-noise ratio, the shape of the inferior patellar pole, and the location of the patellar tendon insertion. Results The tendon-patella angle was not significantly different between groups at any flexion angle, with or without quadriceps muscle activation. The insertion site of the patellar tendon differed significantly but not the shape of the inferior pole of the patella. The volume and the signal difference-to-noise ratio of zones of increased intratendinous signal as well as the anteroposterior diameter of the proximal patellar tendon were increased in symptomatic knees. Conclusions The relationship between the patella and the patellar tendon was identical in both groups; therefore, chronic overload seems to be a major cause of patellar tendinitis.

A pharmacokinetic and MRI study of unilamellar gadolinium-, manganese-, and iron-DTPA-stearate liposomes as organ-specific contrast agents

Small unilamellar liposomes that contain the lipophilic chelate DTPA-stearate (DTPASA) were used as carriers for the paramagnetic metal ions gadolinium, manganese, and iron. The iron liposomes were unstable in vitro and thus not studied further. The natural targeting properties of these liposomes to the reticuloendothelial system was used in rats and dogs for the imaging of liver and spleen. In vitro incubations with human plasma, followed by high-pressure liquid chromatography (HPLC) separation of the Gd-DTPASA and Mn-DTPASA liposomes showed that after an incubation period of 24 hours, only 4% of the gadolinium was bound to the plasma proteins, whereas, with the Mn-DTPASA liposomes, a transfer of 40% manganese was seen. These results indicate that the Mn-DTPASA complex is not stable. On T1-weighted images, both liposome preparations gave a strong signal enhancement of the organs of the mononuclear phagocyte system (MPS). Gadolinium liposomes accumulated in the liver of rats at a peak concentration 4 hours after application and at a higher concentration compared with the manganese liposomes. Gd-DTPASA liposomes had an elimination half-time from the liver of 61 hours. Manganese liposomes produced stronger contrast at lower concentrations and had faster elimination kinetics from the liver, with a major elimination half-time of 10 hours. Both chelate complexes were eliminated predominantly by the hepatobiliary route. Thus, liposomal Gd-DTPASA appears to be a stable, efficient, and specific magnetic resonance imaging (MRI) contrast agent for the upper abdomen.

Anterior chest wall inflammation by whole-body magnetic resonance imaging in patients with spondyloarthritis: lack of association between clinical and imaging findings in a cross-sectional study

IntroductionInflammatory involvement of the anterior chest wall (ACW) affects the quality of life of patients with spondyloarthritis (SpA), although involvement of the ACW is often neglected on clinical and imaging evaluation. Whole-body (WB) MRI is an imaging method used to assess the ACW in addition to the sacroiliac joints and spine without inconvenience for patients. Our goals in this study were to describe the distribution of ACW inflammation by WB MRI in both early and established SpA and associations between clinical and imaging findings indicative of inflammation.MethodsThe ACWs of 122 consecutive SpA patients (95 with ankylosing spondylitis (AS) and 27 with nonradiographic SpA (nrSpA)) and 75 healthy controls were scanned by sagittal and coronal WB MRI. The MRI scans were scored independently in random order by seven readers blinded to patient identifiers. Active and structural inflammatory lesions of the ACW were recorded on a web-based data entry form. ACW pain by patient self-report, ACW tenderness on physical examination according to the Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) and lesions detected by MRI were analyzed descriptively. κ statistics served to assess the agreement between clinical and imaging findings.ResultsACW pain or tenderness was present in 26% of patients, with little difference between AS and nrSpA patients. Bone marrow edema (BME), erosion and fat infiltration were recorded in 44.3%, 34.4% and 27.0% of SpA patients and in 9.3%, 12.0% and 5.3% of controls, respectively. Lesions found by MRI occurred more frequently in AS patients (BME, erosion and fat infiltration in 49.5%, 36.8% and 33.7%, respectively) than in nrSpA patients (25.9%, 25.9% and 3.7%, respectively). The joint most frequently affected by lesions found on MRI scans was the manubriosternal joint. The κ values between clinical assessments and MRI inflammation ranged from -0.10 to only 0.33 for both AS and nrSpA patients.ConclusionsAmong SpA patients, 26% had clinical involvement of the ACW. WB MRI signs of ACW inflammation were found in a substantial proportion of patients with AS (49.5%) and nrSpA (25.9%). There was no association between clinical assessments of ACW, including the MASES, and MRI features.

Small unilamellar liposomes as magnetic resonance contrast agents loaded with paramagnetic Mn-, Gd-, and Fe-DTPA—stearate complexes

Summary Small unilamellar liposomes were used as carriers for paramagnetic ions to enhance proton relaxation times for magnetic resonance imaging (MRI). The metal ions Fe 3 +, Gd 3 ÷ and Mn 2 ÷ were complexed to liposomes containing various amounts (20-60 mol%) of the lipophilic chelator diethylenetriamine pentaacetic acid (DTPA)-stearate (DTPA-SA). The Mn- and Gd-DTPA-SA liposomes were stable for more than two months and had a mean diameter of 26-36 nm, whereas for the Fe-DTPA-SA liposomes, vesicle sizes up to 2 #m were obtained. Due to their large size the Fe-DTPA-SA liposomes were not further studied. The efficiency of metal complexing averaged at 53 + 16%, suggesting that the binding of the metal ions is restricted to the outer liposome surface. The complexing capacity was 3.5-11 #mol, corresponding to 0.2-0.6 mg manganese or 0.55-1.7 mg gadolinium per ml liposomes. In vitro release of metal ions was very low, namely 0.4% for gadolinium, 1.8% for manganese and 5% for iron, determined 5 days after complex formation. Pharmacokinetics and organ distribution of radioactive 54Mn and 153Gd-DTPA-SA liposomes (0.03 mM/kg b.wt.) in rats revealed that approximately 35% of the Mn-liposomes were present in the liver after 30-60 minutes with more than 80% eliminated after 24 h. Mn-DTPA-SA was eliminated from the liver by biphasic kinetics with tl/2(1 ) = 20 min and ta/2(2 ) = 10 h. Different results were obtained with Gd-DTPA-SA liposomes with a slower liver absorption over 2-4 h (35-60%) and a slow elimination with tl/2(2 ) = 80 h. Eight days after injection, 17% of the Gd-DTPA-SA could still be detected in the liver. Both complexes are predominantly eliminated through the hepato-biliary route. The very low metal concentrations found in the kidneys suggest that the metal complexes remain stable. Imaging experiments in rats showed that Mn-DTPA-SA liposomes at 0.03 mM/kg b.wt. gave a signal enhancement on T1 weighted images making the liver as bright as fat tissue. Images taken with Gd-DTPA-SA liposomes at the corresponding concentration gave a smaller, but still significant liver signal intensity increase. The DTPA-SA liposomes used as ligands for paramagnetic metals proved to be very efficient signal enhancers of the reticuloendothelial system (RES), mainly for the liver. The Mn-DTPA-SA liposomes in particular, produce a very strong signal enhancement and due to their fast elimination they might represent a viable contrast agent for MR-imaging of the upper abdomen.

Semiautomated ROI analysis in dynamic MR studies. Part II: Application to renal function examination

Fast MR techniques and the application of water-soluble contrast agents allow the simultaneous examination of renal morphology and the functional aspects of glomerular filtration using bolus injections of Gd-DTPA. Spatial resolution is sufficient to resolve individual renal pyramids, but the quantitative examination of regions of interest (ROIs) is severely impeded by organ movements due to variations of the end-inspiratory position. A new image-processing scheme has been used and tested in 23 normal volunteers and patients. This scheme replaces a tedious frame-by-frame ROI analysis by positional correction of renal regions of all frames of the sequence such that the definition of the regions has to be performed only once. The signal intensities (SIs) of the local regions in each frame are used to compute statistics and to generate curves representing local temporal SI changes due to contrast agent excretion. The success rate of the procedure depends largely on the image quality and on the adherence to a proved acquisition protocol. The present article shows that the combination of MR and robust and reliable image-processing methods can be important for the highly automated analysis of a large number of images acquired as dynamic studies.

Uptake of a monoclonal antibody against CEA (Tumak 431/31) in a human colon tumor (Co-112) xenografted in the nude mouse

SummaryA monoclonal antibody (Tumak) against carcinoembryonic antigen (CEA) was injected into nude mice bearing a human colon carcinoma (Co-112). The tumor uptake was found to be dependent on the size of the tumors: relative uptake (percentage of the injected dose/gram tumor (% i. d./g) decreased for tumors with weights up to ∼1 g, although the absolute uptake (% i. d./tumor) still increased over the same weight range. In the constant region (≥1 g) mean relative tumor uptake was ∼4% i. d./g.The same tumor size dependence was found for the relative Tumak uptake in the other mouse organs studied (e.g., blood, liver, spleen and muscle). Consequently tumor/organ ratios were found to be independent of tumor size.Tumor uptake was also studied for various doses of Tumak (0.07–120 μg) in tumors of ∼1 g. Evidence was found for a threshold dose of 0.1 μg under which no serious tumor uptake appeared. From 1 to 120 μg no further dependence of Tumak distribution on applied dose was found: the relative uptake of all organs remained the same but the absolute uptake increased with dose.

Fast spin echo MRI and bone scintigraphy in the detection of skeletal metastases

Standard Spin Echo (SE) magnetic resonance imaging (MRI) is known to be a very sensitive method for the detection of bone metastases and in comparison to skeletal scintigraphy, MRI detects more lesions when field of view includes the area of suspicion. However, only with the introduction of new fast SE sequences, have MRI protocols, for the detection of metastases, become rapid enough to make it a potential screening procedure for metastatic disease. Twenty-one patients with a suspicion of carcinomatous bone metastases were evaluated with both conventional T1 weighted (T1w), T2 weighted (T2w) and fast T2w SE (FSE) sequences (thoraco-lumbar spine and pelvis) and whole body bone scintigraphy. Conventional and fast T2w SE sequences detected the same number of lesions while bone scintigraphy detected only 70% of the lesions seen on MRI. However, more importantly, in 11 of the 21 patients bone scintigraphy detected lesions outside the MR field of view, lying in the ribs, skull, scapulae and extremities and in 4 of them, MRI was negative. Our results suggest first that fast SE MRI can replace conventional SE MRI when looking for carcinomatous bone metastases in the axial skeleton, with the advantage of a four to six times reduced acquisition time for fast T2w sequences. However, the limited field of view still limits the usefulness of MRI and whole body bone scintigraphy remains the screening modality for bone metastases. Fast MRI plays an important complementary role.

MRI, CT, sonography and thallium-technetium subtraction scintigraphy for the detection of parathyroid disease: a four-year experience

Sonography, subtraction scintigraphy, computed tomography and MRI were compared in 100 patients who had surgery 105 times for hyperparathyroidism (HPT). Surgical and pathological data were available for all operations. A total of 105 MR, 77 CT, 84 sonograms and 70 subtraction scintigrams were performed. The ability of the imaging modalities, individually and in combination, to detect HPT, histology, size, concomitant thyroid disease and location of the diseased glands has been evaluated. For primary HPT, sensitivity ranged from 68% for MRI to 40% for scintigraphy but was much lower for tertiary HPT with all modalities. The ability to identify diseased glands was strongly size dependent for all methods. If patients had had previous neck surgery, the most sensitive methods were MRI and scintigraphy and this also held true for patients with concomitant thyroid disease and ectopically located glands.The findings presented suggest that while sonography may be the only imaging examiantion warranted in newly diagnosed parathyroid disease, recurrent disease should be examined pre-operatively with MRI and possibly subtraction scintigraphy.

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.

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

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.