[Inflammatory muscle diseases (myositis)]. / Entzündliche Muskelerkrankungen (Myositiden).

CLINICAL ISSUE: Inflammatory muscle diseases are quite heterogeneous and frequently a specific diagnosis is not easy. STANDARD RADIOLOGICAL METHODS: Magnetic resonance imaging (MRI) is best suited to demonstrate pattern and size of inflamed muscles. PERFORMANCE: Sensitivity of MRI in showing inflamed muscles is nearly 100%. Specificity, however, is much lower. PRACTICAL RECOMMENDATIONS: In cases of suspected bacterial myositis, sonography may be used to exclude abscess formation prior to MRI for more precise information about inflamed muscles.

[CT-guided steroid injection into disc herniation: a causative therapy for lower back pain due to disc herniation]. / CT-gesteuerte Prolaps-Steroidinjektion: Eine kausale Therapie des bandscheibenprolapsassoziierten Schmerzsyndroms.

PURPOSE: To evaluate the therapeutic benefit of CT-guided steroid injection into disc herniations. MATERIALS AND METHODS: In 64 patients, 2.5 mg Dexamethasone was injected into a symptomatic disc herniation under CT-guidance. Conservative treatment 3 to 12 months before injection was unsuccessful. Classified as "complete relief", "strong relief", "mild relief" and "no relief" of pain, the change of discomfort and pain was registered at 14 days, 3 months and 6 months after injection while the conservative regimen continued. RESULTS: At 14 days after injection, 36 patients (56 %) showed complete relief, 5 strong relief (8 %), 12 mild relief (19 %) and 11 no relief (17 %). At 6 months after injection, 25 patients showed complete relief (39 %), 16 strong relief (25 %), and 23 no relief (36 %). One complicating spondylodiscitis was observed. CONCLUSION: CT-guided steroid injection into symptomatic disc herniation represents a therapeutic alternative with good therapeutic results. It can be recommended as an alterative to other minimal invasive therapeutic regimens. The disc material acts as reservoir for the drug with good long term depot effect.

Site-matched calcaneal measurements of broad-band ultrasound attenuation and single X-ray absorptiometry: do they measure different skeletal properties?

Because of the differences in the interactions of ultrasound and x-ray waves with bone, quantitative ultrasound (QUS) techniques may yield information about skeletal status not accessible by regular bone densitometry (BD) techniques. However, relatively strong correlations have been reported between broad-band ultrasound attenuation (BUA) and several x-ray-based BD methods. We assessed the precision and association of single x-ray absorptiometry (SXA) and BUA of the calcaneus. We examined both BUA and SXA at the calcaneus using special software for matching the regions of interest. An algorithm was derived and applied to correct the observed correlation coefficients for the attenuation effect caused by the precision errors for BUA and SXA. In a group of 33 volunteers covering a wide range of age and calcaneal bone mineral densities, the site-matched and precision-adjusted correlation coefficient between BUA and SXA was r = 0.58, with a standard error of the estimate (SEE) of 14.41 dB/MHz, or 17.08%. For the subgroup of 25 women the correlation was stronger, with r = 0.72 and SEE = 11.53 dB/MHz, or 14.33%. SXA precision was 0.79% for the regular region of interest (ROI) and 1.22% for the site-matched ROI. BUA precision was 2.76% for the entire subject group and 1.63% for women of age 40 or older. The observed correlation coefficient between ultrasound and x-ray based techniques of the order of 0.7 is significant, but it leaves about 50% of the variability unexplained.(ABSTRACT TRUNCATED AT 250 WORDS)

Shoulder MRI: the subacromial/subdeltoid bursa fat stripe in healthy and pathologic conditions.

The MRI appearance of the subacromial/subdeltoid (SA-SD) bursa is described here in both healthy and pathological conditions. Based on one case of rotator cuff tear and intrabursal fluid outlined by two adjacent fat stripes we reviewed 20 shoulder MR examinations to define the normal and abnormal appearance of the peribursal fat. We found four pathological patterns: lateral displacement, tear-drop configuration, obliteration and double fat stripe.

Shoulder MRI after surgical treatment of instability.

OBJECTIVE: To analyze magnetic resonance imaging (MRI) findings of the shoulder after an instability operation. MATERIALS AND METHODS: Physical examinations, radiographs and MRI of 10 patients after anterior glenoid bone block insertion for ventral instability were compared. MRI included T1-weighted spin-echo (TR = 600, TE = 20 ms) and T2*-weighted gradient-echo sequences (TE = 600, TE = 18, Flip = 30 degrees) in the axial, oblique-coronal and oblique-sagittal planes. RESULTS: No patient suffered from recurrent subluxation. We found fusion of the bone block with the anterior glenoid in seven cases, dislocation of the bone block without contact to the glenoid in one case, and no visible bone block in two cases. On MRI, the bone block showed either signal intensity equivalent to fatty bone marrow (n = 4) or was devoid of signal consistent with cortical bone or bone sclerosis (n = 4). In all patients, a low signal intensity mass, 2-4 cm in diameter, was visible next to the glenoid insertion site. CONCLUSION: Insertion of a bone block onto the anterior glenoid induces formation of scar tissue, increasing the stability of the shoulder joint. This scar is well visible on MRI and forms independently of the behavior of the bone block itself. MRI is ideally suited for evaluating postoperative shoulder joints after bone-grafting procedures.

[Magnetization transfer contrast imaging (MTC): its fundamentals, technics and applications]. / Magnetisierungs-Transfer-Kontrast (MTC): Grundlagen, Techniken und Anwendungen.

Using magnetisation transfer (MTC), a new contrast could be achieved on magnetic resonance images (MRI). Two different techniques are available to produce MTC: on- and off-resonance technique. Basic physics of MTC and the two techniques are extensively described in this review article. Potential advantages in using MTC are imaging of cartilage, multiple sclerosis and MR angiography. Particularly the detection of contrast media enhancing brain lesions were improved using MTC. Early cartilage degeneration could be visualised with improved contrast on MTC images. This article gives an overview of potential and accepted applications.

[Magnetic Resonance Imaging (MRI) of the TMJ: Influence on therapy and inter-observer agreement of two radiologists]. / Magnetresonanztomographie (MRT) des Kiefergelenkes: Einfluss auf Therapieentscheidung und Ubereinstimmung zweier Auswerter.

AIM: To evaluate the influence of MRI of the temporomandibular joint on the therapeutic strategy in patients with craniomandibular disorders (internal derangement) and, furthermore, to analyze interobserver agreement for defined MRI criteria. MATERIALS AND METHODS: Fifty-one unilateral and bilateral MRI examinations of 32 patients were enrolled. Therapeutic strategies before and after performance of the MRI were compared. Retrospectively, two radiologists independently analyzed the MR images for position of the disk, position of the condyle, signal intensity of the disk and bilaminar zone, osseous changes and several additional findings, using a check list. Agreement was tested by kappa statistics. RESULTS: In 56% of the cases, changes of the therapeutic regimen were registered after MRI. Statistically significant agreement of the two observers was found for anterior position of the disk (kappa = 0.44), transverse position of the disk (kappa = 0.46) and position of the condyle (kappa = 0.45). No significant agreement was found for signal intensity of the disk (kappa = 0.14) or bilaminar zone (kappa = 0.24), osseous changes (kappa = 0.13) and the additional findings (kappa = 0.29). DISCUSSION: MRI has a measurable impact on the therapeutic approach to the internal derangement of the TMJ. The position of the disk and condyle can be reproducibly judged, while the signal intensity of the disk and bilaminar zone and the osseous changes are subject to wide observer variations.

[Turbo(fast) spin echo at 0.5 T: effect of echo distance and echo number on image contrast]. / Turbo(Fast)-Spinecho bei 0,5 T: Einfluss der Echodistanz und Echozahl auf den Bildkontrast.

Signal intensities, signal-to-noise ratios (S/N), and contrast-to-noise ratios (C/N) in dependence on the echo distance and echo number of the new turbo (fast) spin-echo technique are analysed by phantom, volunteer and patient measurements. With increasing echo number (3 to 15 echoes), signal intensities increase (25 to 50%), S/N varies between different tissues, and C/N of fat to water decreases (70%). A high echo number, although it shortens the imaging time, is thus not always the best choice since the fat/water contrast is lost. However, a high fat/water contrast is advantageous for several MR applications.

[Humeroradial plica: frequency and visualization on MRI]. / Plica humeroradialis: Inzidenz und MR-tomographische Darstellbarkeit.

PURPOSE: To determine frequency and size of a humeroradial plica and correlate it with degenerative changes, and to determine frequency of the visualization of a synovial fold on MR-Images (T1-weighted spin-echo and STIR sequences) and correlate it with degenerative changes. MATERIALS AND METHODS: Forty-two elbow specimens were dissected and studied for humeroradial synovial folds (small, medium, large) and degenerative changes (absent, medium, strong), and 88 elbow MR-images were analyzed for a synovial fold (not visible, small, large) and degenerative changes (absent, medium, strong). Comparison was performed using the chi (2) test. RESULTS: Dissections revealed a synovial fold in all cases. The sizes were small in n = 13 (31 %), medium in n = 24 (57 %), and large in n = 5 (12 %). Degenerative changes were absent in n = 9 (21.4 %), medium in n = 29 (69 %), and strong in n = 4 (9.6 %). On MRI the synovial fold was not visible in n = 67 (76 %), small in n = 12 (14 %), and large in n = 9 (10 %). Degenerative changes on MRI were absent in n = 65 (74 %), medium in n = 15 (17 %), and strong in n = 8 (9 %). The size of the fold correlated positively with degenerative changes in the specimen but not with degenerative changes on MRI. The T1-SE sequence was superior to the STIR sequence in revealing the synovial fold. DISCUSSION: A humeroradial plica is a regular finding, but visualized by MRI in only approximately 20 %, probably due to its variable size. Its visualization succeeds best with T1-spin-echo sequences.

[Magnetization transfer contrast (MTC)--which is the most MTC-sensitive MRI sequence?]. / Magnetization Transfer Contrast (MTC)--Welches ist die MTC-sensitivste MRT-Sequenz?

PURPOSE: This study aimed at evaluating MTC-sensitivity of frequently used MR-sequences. MATERIAL AND METHODS: 7 sequences (T1-, T2-, PD-weighted SE, four gradient-echo sequences) were combined with a 4 element on-resonance MT-Pulse at 0.5 Tesla (T5, Philips medical systems). The measurements were performed at a knee joint and MT-ratios of cartilage, muscle, fat and a copper sulfate phantom were calculated. RESULTS: Proton density weighted gradient and to a lesser degree spin-echo sequences were superior to T1- and T2-weighted sequences in visualising the MT effects. CONCLUSION: It is important to choose an appropriate MR-sequence for MTC experiments. Proton-density gradient echo sequences are recommended for that purpose. T1- and T2-weighted SE sequences should be avoided.

[The quantification of the magnetization transfer contrast (MTC) effect by calculating MT quotients: does it yield additional information for the differentiation of benign and malignant diseases of the locomotor apparatus?]. / Quantifizierung des Magnetization Transfer Contrast (MTC) Effektes durch Berechnung von MT-Quotienten: ergeben sich Zusatzinformationen für die Differenzierung benigner und maligner Erkrankungen des Bewegungsapparates?

PURPOSE: To investigate the potential information of the amount of magnetization-transfer effect in musculoskeletal lesions and to compare MT ratios from benign and malignant musculoskeletal lesions. MATERIAL AND METHOD: 49 patients with malignant tumors (3 osteosarcoma, 3 malignant fibrous histiocytoma, 4 chondrosarcoma, 2 Ewing sarcomas) and benign lesions (8 chondroma, 2 fibrous dysplasia, 3 osteoid-osteoma, 6 ganglion cyst, 3 cyst, 3 osteomyelitis, 4 tendinitis, 3 rotator cuff tear, 5 scar tissue) were scanned using routine MRI protocols including T1- and T2-weighted spin echo as well as T2*-weighted gradient echo (FFE) sequences at 1.5 Tesla (ACS II, Philips Medical). Additionally MTC images were generated by combining the FFE sequence and the off-resonance MT technique (-1500 Hz off-resonance frequency, 1770 degrees flip angle and 50 ms pulse duration). MT ratios were calculated as Slo-Slm/Slo. RESULTS: The MT ratio of benign lesions was 26 +/- 15%, that of malignant lesions was 22 +/- 6%. The difference was statistically not significant. As expected muscle showed a high MT ratio of 50 +/- 8%. Scar tissue demonstrated an MT ratio of 39 +/- 16% which was significantly higher than the tumor MT ratios. CONCLUSION: MTC (MT ratios) failed to show significant differences between benign and malignant lesions as was expected due to basic differences in cellularity, rate of mitosis and chromatin content. MTC might however gain more importance in separating scar tissue from recurrent tumor in the future.

[Magnetic resonance tomography using the fast STIR technique: optimization and a comparison with other sequences in a 0.5-Tesla system]. / Magnetresonanztomographie mit schneller STIR-Technik: Optimierung und Vergleich mit anderen Sequenzen an einem 0.5-Tesla-System.

One disadvantage of the STIR sequence in MRI is its long acquisition time. A TR shortening for acceleration requires shortening of the inversion time depending upon the field strength. We optimized this "fast-STIR" technique at 0.5 T using calculations, phantom, volunteer, and patient measurements. This optimization procedure is transferable to other field strengths. The resulting sequence takes 4.5 minutes, fat is visualised signal-free. In the second part of our study we compared quantitatively and qualitatively the signal intensities, contrast, and sensitivity towards artifacts of this sequence with that of conventional SE and GRE sequences in 21 patients with neoplastic, inflammatory and traumatic disorders of the musculoskeletal system. The fast-STIR sequence showed similar or better lesion contrast as SE in 100% and as GRE in 88%. Decreased spatial resolution and higher sensitivity towards pulsatile artifacts of the fast-STIR sequence were only minor drawbacks.

[Magnetic resonance imaging (MRI) of the bursa around the knee joint]. / Magnetresonanztomographie (MRT) der Bursae um das Kniegelenk.

INTRODUCTION: Since fluid filled bursae lead to visible structures on MR images it is important to establish criteria to recognize them and to differentiate them from tumorous fluid-like structures. With this study the bursae around the knee joint were analyzed for potential differential diagnostic criteria such as localisation, size and shape. MATERIAL AND METHODS: In a retrospective study of 133 MR exams the frequency, localization and morphology were registered. The frequency of occurrence was correlated with the frequency of an effusion by means of the chi 2 test. RESULTS: The most frequently recognized bursae were bursa subtendinea musculi gastrocnemii medialis (54.9%), bursa musculi semimembranosi (21%), and bursa infrapatellaris profunda (18.8%). 8 different bursae were identified in complete. Size roanged from 2 to 18 mm. The shape was round and ovoid. The bursa subtendinea musculi gastrocnemii medialis and bursa musculi semimembranosi correlated with the occureance of an effusion. CONCLUSION: Bursae around the knee are frequently visualized as asymptomatic fluid like structures. Knowledge of the typical localization, size and contour is important for identification and differentiation diagnosis against ganglia, cysts or joint recesses.

[Osteoporosis diagnosis by broad-band ultrasound attenuation (BUA): its correlation with established measurement procedures of bone densitometry]. / Osteoporosediagnostik mittels Breitband-Ultraschallabschwächung (BUA): Korrelation zu etablierten Messverfahren der Knochendensitometrie.

Broadband ultrasound attenuation (BUA) measurements of the os calcis of 54 women were correlated to single-energy x-ray absorptiometry (SXA) of the os calcis, dual-energy x-ray absorptiometry (DXA) of the lumbar spine, age and weight. The reproducibility of the BUA measurements was 2.1%. BUA was significantly correlated with SXA (r = 0.7), DXA (r = 0.5) and age (r = 0.6). BUA values ranged from 42 to 117 dB/MHz. Our results confirm BUA's potential as a simple, inexpensive, radiation free, and precise alternative technique for osteoporosis diagnostics of the os calcis. However, the correlation observed with bone mineral density of the spine is too weak to use BUA for predicting the lumbar density status. The ability of BUA to predict the risk of osteoporotic fractures has to be determined directly by assessing the association of BUA and the prevalence or preferably the incidence of fractures.

[Distribution of hematopoietic and fatty bone marrow in the proximal humerus and scapula: magnetic resonance tomography and macroscopic anatomy]. / Verteilung von hämatopoetischem und fettreichem Knochenmark im proximalen Humerus und in der Skapula: Magnetresonanztomographie und makroskopische Anatomie.

PURPOSE: To establish the distribution pattern of haematopoietic and fatty bone marrow on MRI of the proximal humerus and the scapula in correlation with age, gender and nutritive factors. MATERIAL AND METHODS: 32 shoulder MR examinations (T1-weighted spin-echo and opposed-phase gradient-echo sequences) from 24 patients and 8 volunteers were analysed retrospectively. The amount of haematopoietic bone marrow within the proximal humerus and scapula was classified into four groups and was correlated with age (H-test), gender (chi 2-Test), and thickness of subcutaneous fat (H-test). The marrow distribution within 10 scapulae of cadavers over 60 years of age at death was studied. RESULTS: With increasing age, the amount of haematopoietic bone marrow in the proximal humeral metaphysis tends to decrease from lateral towards medial (H-test, p = 0.3). Diaphysis and epiphysis did not show haematopoietic marrow. The amount of haematopoietic bone marrow within the paraglenoid region of the scapula also revealed a decrease with increasing age (H-test, p = 0.003). Females had higher amounts of haematopoietic marrow than males (chi 2-test, p = 0.03). The thickness of subcutaneous fat was independent of the marrow distribution. CONCLUSION: The amount of haematopoietic bone-marrow of the shoulder girdle decreases with increasing age. The knowledge of marrow distribution patterns based upon these changes is important for shoulder MRI interpretation to prevent confusion with infiltrative disease.

[Turbo-spin-echo (TSE) sequences with selective fat suppression (SPIR) compared with chemical shift sequences in MRI for differentiation of adrenal tumors. Spectral Presaturation by Inversion Recovery]. / Turbo-Spin-Echo(TSE)-Sequenzen mit selektiver Fettunterdrückung (SPIR) gegenüber Chemical-Shift-Sequenzen in der MRT zur Differenzierung von Nebennierentumoren.

AIM: The value of chemical-shift-gradient-echo sequences and turbo-spin-echo sequences with selective fat suppression (SPIR = Spectral Presaturation by Inversion Recovery) in the differentiation of benign and malignant adrenal tumours was investigated. METHODS: Both techniques were performed at 1.5 T in 22 patients with 24 tumours. The loss of signal intensity of the tumour or of the signal intensity ratio between tumour and liver or muscle on the opposed phase Fast-Field-Echo (FFE) sequence in comparison to the in phase FFE sequence or on the TSE-SPIR sequence compared to the TSE sequence was the criterion for intratumoral lipid, suggesting a benign mass. RESULTS: The sensitivity and specificity of the chemical shift technique was 62-77 and 100%, respectively. In adrenal tumours larger than 1.5 cm sensitivity of the chemical-shift technique was 89%. On the contrary sensitivity of the TSE-SPIR sequence was only 11-78%. Both techniques had a specificity of 100%. CONCLUSION: The chemical shift technique is more accurate in the differentiation of adrenal masses than the TSE-SPIR sequence.

[Fat-suppressing STIR sequences with and without contrast media in the MRT of ENT tumors]. / Fettunterdrückende STIR-Sequenzen mit und ohne Kontrastmittel bei der MRT von HNO-Tumoren.

Fat-suppressed STIR (short TI inversion recovery) sequences were compared to plain and contrast-enhanced T1-weighted SE sequences of head and neck tumors. 19 patients underwent MR imaging on a 0.5 Telsa system (T5-II, Philips). STIR imaging parameters: TR/TE = 1000/20 ms, inversion pulse 100 ms. All films were read by four radiologists. The image quality was graded: score from 0 to 5, by means that grade 5 = optimal quality. Sensitivity was 89% in STIR, 96% in SE sequences. Tumor delineation was graded good in the enhanced T1-weighted and enhanced fat suppression images. The unenhanced imaging was superior in STIR (STIR/T1 = 2.8/2.43). The tumor contrast was best in contrast enhanced and plain STIR sequences (STIR contrast = 3.41), and in the contrast enhanced T1-weighted SE (3.33). STIR almost equaled T1 post-contrast in respect of tumour conspicuity, but the sensitivity was lower. STIR can be a supplement to SE, but cannot substitute T1 postcontrast. The combined use is expected to have the highest assessment value.

[Residual and reconverted hematopoietic bone marrow in the distal femur. Spin-echo and opposed-phase gradient-echo MRT]. / Residuales und rekonvertiertes hämatopoetisches Knochenmark im distalen Femur. Spinecho und gegenphasierte Gradientenecho-MRT.

The distal femur contains usually only fatty marrow in the adult. We investigated the incidence of areas of residual and reconverted hematopoietic marrow in the distal femur in a series of 50 adult patients using conventional spin-echo and opposed-phase gradient-echo MR images. Zones with intermediate to low signal intensity in both sequences representing hematopoietic marrow within high signal intensity fatty marrow were observed in 17 of the 50 patients. Opposed-phase gradient-echo sequences demonstrated significantly greater red-yellow marrow contrast than conventional spin-echo sequences. Residual red marrow may represent a biologic variation of the normal adult pattern of red-yellow marrow distribution in women of menstruating age. Reconverted red marrow appears to be related to increased erythrocyte demand. It should not be mistaken for bone marrow malignancy. Absence of epiphyseal involvement, cortical destruction and soft-tissue mass in residual and reconverted hematopoietic marrow are helpful differential criteria.

[Indirect MR arthrography in the diagnosis of lesions of the labrum glenoidale]. / Indirekte MR-Arthrographie in der Diagnostik von Läsionen des Labrum glenoidale.

PURPOSE: It has been shown that intravenous administration of contrast media produces an MR arthrographic effect without the need for intraarticular injection. This is the first study evaluating this new technique of indirect MR arthrography in the diagnosis of glenoid labrum tears. METHODS: 28 patients with clinically suspected labral injuries were prospectively investigated (1.5 Tesla, flexible surface coil). A plain MR examination of the shoulder (transverse and oblique-coronal orientation, T1-weighted spin- [TE/TR 15/675], proton density- and T2*-weighted gradient echo [TE/TR/Flip 14,32/600/30 degrees] sequences) and indirect MR arthrography (transverse and oblique-coronal orientation, fat-suppressed T1-weighted spin-echo sequences [TE/TR 15/675], intravenous injection of gadopentetate dimeglumine [0.1 mmol/kg], followed by 10-15 min of joint movement) were performed. Results were confirmed by arthroscopy and/or open surgery. RESULTS: Indirect MR arthrography significantly improved delineation of the glenoid labrum and hyaline cartilage (p < 0.05). Sensitivity and specificity of indirect MR arthrography in the diagnosis of labral injuries were 90% and 89%, compared to 79% and 67% of the native MR examination. CONCLUSION: Indirect MR arthrography is a promising non-invasive technique in the evaluation of the glenoid labrum.

[Spontaneous osteonecrosis of the knee joint: MRT compared to CT, scintigraphy and histology]. / Spontane Osteonekrose des Kniegelenkes: MRT im Vergleich zur CT, Szintigraphie und Histologie.

PURPOSE: We compared MR imaging with scintigraphy and CT in eight patients with spontaneous osteonecrosis of the knee. The histological changes accounting for the MR signal abnormalities were evaluated. METHODS: Eight patients with spontaneous osteonecrosis of the knee joint underwent MR imaging before and after i.v. administration of Gd-DTPA. Nuclear scintigraphy was performed in all 8 patients, three patients also had CT scans of the knee area. Histologic correlation was available in three patients. RESULTS: Increased radionuclide uptake was observed in all patients. In one patient, however, scintigraphy showed increased radionuclide uptake consistent with osteonecrosis only in the medial femoral condyle, while MR imaging demonstrated osteonecrosis both in the medial as well as the lateral femoral condyles. MR demonstrated areas of low signal intensity on precontrast T1-weighted images in the femoral condyle in all patients. All these areas showed high signal intensity on T2-weighted images. On postcontrast T1-weighted images, signal intensity increase was either homogeneous throughout the lesion or it was seen at the periphery of the lesion in a band-like pattern. Histologically, the areas of high signal intensity on T2-weighted and on postcontrast T1-weighted images corresponded to granulation tissue. CONCLUSION: MR imaging detects granulation tissue adjacent to the necrotic zone. Using morphological and signal intensity criteria, MR imaging can be utilised to differentiate spontaneous osteonecrosis of the knee from osteochondritis dissecans, degenerative osteoarthritis, and other conditions affecting the knee joint.