Effect of rheumatoid arthritis and age on metacarpal bone shaft geometry and density: A longitudinal pQCT study in postmenopausal women

OBJECTIVE

This study aimed to elucidate the effects of changes in the geometry and density of the metacarpal bone of patients with rheumatoid arthritis (RA).

METHODS

This prospective study included consecutive postmenopausal RA patients who met the American College of Rheumatology Criteria and healthy controls (HC). Peripheral quantitative computed tomography scans at 50% of the total metacarpal shaft (third metacarpal bone) were obtained at baseline and follow-ups. Use of bisphosphonates (BP), glucocorticoids (GC), biologics, and disease-modifying anti-rheumatic drugs (DMARD) was monitored (baseline to follow-up). Total cross-sectional area (CSA), cortical-transitional zone and compact zone CSA, cortical volumetric bone mineral density, and compact cortex porosity were measured. A linear mixed-effects model was used to determine significant differences in the rate of change in the RA and control groups and in RA patient subgroups.

RESULTS

Thirty-nine RA patients and 42 consecutive postmenopausal HC were followed for 63 months. RA and HC depicted a time-dependent increase of medullary CSA (+0.41 mm²/year, P < 0.0001), while total CSA remained stable (P = 0.2). RA status was associated with a loss of cortical bone mineral density (interaction: -3.08 mg/mm³; P = 0.014). In RA subgroup analysis, GC use ≥5 mg/day was positively correlated with a fourfold increase of medullary CSA (0.67 mm²/year P = 0.009), which resulted in a three- to fourfold loss of cortical density (-6.6 mg/mm³/year; P = 0.002) and cortical CSA (-0.57 mm²/year, P = 0.004). Patients with high disease activity and high GC dose at baseline demonstrated an increase in the total CSA (0.29 mm²/y; P = 0.049) and a loss of cortical BMD (-5.73 mg/mm³/y; P = 0.05) despite good clinical response.

CONCLUSION

Increase in medullary metacarpal CSA and thinning of the cortical CSA are physiological and time dependent. RA status is associated with loss in cortical density. Even upon biological therapy, low glucocorticoid dose affects metacarpal bone shaft geometry and density over time.

Mapping tibiofemoral gonarthrosis: an MRI analysis of non-traumatic knee cartilage defects

OBJECTIVE

Arthroscopy is "the gold standard" for the diagnosis of knee cartilage lesions. However, it is invasive and expensive, and displays all the potential complications of an open surgical procedure. Ultra-high-field MRI now offers good opportunities for the indirect assessment of the integrity and structural changes of joint cartilage of the knee. The goal of the present study is to determine the site of early cartilaginous lesions in adults with non-traumatic knee pain.

METHODS

3-T MRI examinations of 200 asymptomatic knees with standard and three-dimensional double-echo steady-state (3D-DESS) cartilage-specific sequences were prospectively studied for early degenerative lesions of the tibiofemoral joint. Lesions were classified and mapped using the modified Outerbridge and modified International Cartilage Repair Society classifications.

RESULTS

A total of 1437 lesions were detected: 56.1% grade I, 33.5% grade II, 7.2% grade III and 3.3% grade IV. Cartographically, grade I lesions were most common in the anteromedial tibial areas; grade II lesions in the anteromedial L5 femoral areas; and grade III in the centromedial M2 femoral areas.

CONCLUSION

3-T MRI with standard and 3D-DESS cartilage-specific sequences demonstrated that areas predisposed to early osteoarthritis are the central, lateral and ventromedial tibial plateau, as well as the central and medial femoral condyle.

ADVANCES IN KNOWLEDGE

In contrast with previous studies reporting early cartilaginous lesions in the medial tibial compartment and/or in the medial femoral condyle, this study demonstrates that, regardless of grade, lesions preferentially occur at the L5 and M4 tibial and L5 and L2 femoral areas of the knee joint.

Evaluation of articular cartilage in patients with femoroacetabular impingement (FAI) using T2* mapping at different time points at 3.0 Tesla MRI: a feasibility study

OBJECTIVES

To define the feasibility of utilizing T2* mapping for assessment of early cartilage degeneration prior to surgery in patients with symptomatic femoroacetabular impingement (FAI), we compared cartilage of the hip joint in patients with FAI and healthy volunteers using T2* mapping at 3.0 Tesla over time.

MATERIALS AND METHODS

Twenty-two patients (13 females and 9 males; mean age 28.1 years) with clinical signs of FAI and Tönnis grade ≤ 1 on anterior-posterior x-ray and 35 healthy age-matched volunteers were examined at a 3 T MRI using a flexible body coil. T2* maps were calculated from sagittal- and coronal-oriented gradient-multi-echo sequences using six echoes (TR 125, TE 4.41/8.49/12.57/16.65/20.73/24.81, scan time 4.02 min), both measured at beginning and end of the scan (45 min time span between measurements). Region of interest analysis was manually performed on four consecutive slices for superior and anterior cartilage. Mean T2* values were compared among patients and volunteers, as well as over time using analysis of variance and Student's t-test.

RESULTS

Whereas quantitative T2* values for the first measurement did not reveal significant differences between patients and volunteers, either for sagittal (p = 0.644) or coronal images (p = 0.987), at the first measurement, a highly significant difference (p ≤ 0.004) was found for both measurements with time after unloading of the joint. Over time we found decreasing mean T2* values for patients, in contrast to increasing mean T2* relaxation times in volunteers.

CONCLUSION

The study proved the feasibility of utilizing T2* mapping for assessment of early cartilage degeneration in the hip joint in FAI patients at 3 Tesla to predict possible success of joint-preserving surgery. However, we suggest the time point for measuring T2* as an MR biomarker for cartilage and the changes in T2* over time to be of crucial importance for designing an MR protocol in patients with FAI.

Prospective navigator-echo-based real-time triggering of fetal head movement for the reduction of artifacts

The purpose of this study was to evaluate the neuroimaging quality and accuracy of prospective real-time navigator-echo acquisition correction versus untriggered intrauterine magnetic resonance imaging (MRI) techniques. Twenty women in whom fetal motion artifacts compromised the neuroimaging quality of fetal MRI taken during the 28.7 +/- 4 week of pregnancy below diagnostic levels were additionally investigated using a navigator-triggered half-Fourier acquired single-shot turbo-spin echo (HASTE) sequence. Imaging quality was evaluated by two blinded readers applying a rating scale from 1 (not diagnostic) to 5 (excellent). Diagnostic criteria included depiction of the germinal matrix, grey and white matter, CSF, brain stem and cerebellum. Signal-difference-to-noise ratios (SDNRs) in the white matter and germinal zone were quantitatively evaluated. Imaging quality improved in 18/20 patients using the navigator echo technique (2.4 +/- 0.58 vs. 3.65 +/- 0.73 SD, p < 0.01 for all evaluation criteria). In 2/20 patients fetal movement severely impaired image quality in conventional and navigated HASTE. Navigator-echo imaging revealed additional structural brain abnormalities and confirmed diagnosis in 8/20 patients. The accuracy improved from 50% to 90%. Average SDNR increased from 0.7 +/- 7.27 to 19.83 +/- 15.71 (p < 0.01). Navigator-echo-based real-time triggering of fetal head movement is a reliable technique that can deliver diagnostic fetal MR image quality despite vigorous fetal movement.

[Uric acid, a neglected molecule--the value of imaging]

Imaging plays a key role in two longterm effects of hyperuricemia: those on the urinary tract and on the skeletal system. This overview concentrates on the diagnosis of urinary stones and of musculoskeletal gout. Urinary stones are negative on radiography, i.e., they cannot be differentiated from the surrounding tissues, and even at intravenous urography only non specific filling defects are shown that may be hard to differentiate from blood clots and papillary necrosis whereas computed tomography without a contrast agent is highly sensitive in detecting all types of stones whether negative or positive at radiography. Gout of the musculoskeletal system usually manifests as an acute gouty arthritis after a long-standing asymptomatic hyperuricemia. An intercritical phase may follow before new acute attacks and--in up to 50%--chronic gout develop. During acute gouty arthritis imaging is non-specific. The distribution pattern, the relation of soft tissue changes and osteolytic paraarticular changes, calcifications and the lack of osteoporosis are a typical, nearly pathognomonic constellation of chronic tophaceous gout. In selected cases CT or MRI may add critical local information.

Staging of rectal cancer: diagnostic potential of multiplanar reconstructions with MDCT

OBJECTIVE

The purpose of this study was to evaluate whether multiplanar reconstructions (MPRs) of MDCT could improve local staging of rectal cancer.

CONCLUSION

Adding MPRs, on the basis of the MDCT data sets, provides definite improvements in the accurate local staging of rectal cancer compared with standard axial reconstructions alone.

Linear spiradenoma with focal malignant transformation

Malignant spiradenoma is an exceedingly rare adnexal tumour clinically characterized by rapid enlargement of a pre-existing, long-standing benign spiradenoma. Microscopic examination typically reveals a continuum between benign spiradenoma and areas of malignant transformation. Biological behaviour is unpredictable and it should be regarded as a potentially lethal neoplasm. Treatment recommendations require radical surgical excision. The reported case of a 23-year-old female illustrates the malignant transformation of a 1.5 cm nodule within a large linear spiradenoma almost covering the frontal aspect of the lower leg. In reviewing the literature, malignant transformation seems to occur slightly more often in multiple than in solitary spiradenomas. It is unclear whether excision restricted to the malignant area is an advisable treatment option in comparison to total excision of all spiradenoma nodules. In the presented case, the transformed area was excised. The patient is free of recurrence after 2 years.

[Diagnostic value of different rectal contrast media in the detection of colorectal diseases by multi-slice CT]

PURPOSE

Assessment of 3 different rectal contrast agents (water, methylcellulose, ultrasound gel) for their suitability for colorectal imaging in multislice CT (MS-CT).

METHODS

115 patients with colorectal diseases underwent MS-CT with varying, rectal contrast agents in a prospective study. Images were assessed by 2 independent CT-experienced radiologists. 6 criterias were evaluated, using a 5-point scale.

RESULTS

Methylcellulose (MC) proved to be significantly superior to ultrasound gel (US). Especially, differentiation of healthy and diseased bowel and bowel wall and lumen were aided, which was proven by quantitative analysis of attenuation values. Rectal distension is greater using MC or US than for water. More proximal parts of the colon could be better distended with water. The interobserver correlation was good (kappa 0.76).

CONCLUSIONS

Rectal filling with MC significantly improves diagnostic confidence in colorectal examinations. Ease of administration and lack of problems suggest its use as a clinical routine tool.

Magnetic resonance imaging (MRI) controlled outcome of side effects caused by ionizing radiation, treated with 780 nm-diode laser -- preliminary results

BACKGROUND AND OBJECTIVE

Ionizing radiation therapy by way of various beams such as electron, photon and neutron is an established method in tumor treatment. The side effects caused by this treatment such as ulcer, painful mastitis and delay of wound healing are well known, too. Biomodulation by low level laser therapy (LLLT) has become popular as a therapeutic modality for the acceleration of wound healing and the treatment of inflammation. Evidence for this kind of application, however, is not fully understood yet. This study intends to demonstrate the response of biomodulative laser treatment on the side effects caused by ionizing radiation by means of magnetic resonance imaging (MRI).

STUDY DESIGN/PATIENTS AND METHODS

Six female patients suffering from painful mastitis after breast ionizing irradiation and one man suffering from radiogenic ulcer were treated with lambda=780 nm diode laser irradiation at a fluence rate of 5 J/cm2. LLLT was performed for a period of 4-6 weeks (mean sessions: 25 per patient, range 19-35). The tissue response was determined by means of MRI after laser treatment in comparison to MRI prior to the beginning of the LLLT.

RESULTS

All patients showed complete clinical remission. The time-dependent contrast enhancement curve obtained by the evaluation of MR images demonstrated a significant decrease of enhancement features typical for inflammation in the affected area.

CONCLUSION

Biomodulation by LLLT seems to be a promising treatment modality for side effects induced by ionizing radiation.

[MRI-based 3-D analysis of the glenohumeral translation in patients with shoulder instability]

AIM

Until now, pathological translation of the glenohumeral joint could not be assessed three-dimensionally and in functionally important arm positions in the living. The objektive of this study was therefore to develop an MR-based technique for determining the three-dimensional glenohumeral translation in functionally relevant positions in vivo.

METHOD

In an open MR scanner both shoulder joints of 5 volunteers with an unilateral traumatic instability were examined in different positions of abduction and rotation. After semiautomatic segmentation, 3D reconstruction of the bony structures of the shoulder girdle was performed and the center of mass of the glenoid cavity was determined and used as reference point. In a virtual reality, the midpoint of the humeral head was assessed and its position relative to the center of mass of the glenoid cavity was calculated.

RESULTS

At 30 degrees of abduction, in both shoulders, the humeral head was positioned inferior and posterior relative to the glenoid cavity (healthy: 0.42 +/- 1.1 inf., 0.75 +/- 1.0 mm post.; unstable: 1.31 +/- 0.87 mm inf., 0.51 +/- 1.28 mm post.) The maximal translation (to anterior and inferior) was observed both on the healthy side (mean 1.0 mm, max. 1.8 mm) and in the unstable shoulders (mean 2.5 mm, max. 4.6 mm) with the arm in 90 degrees of abduction and external rotation, thus being 1.7 to 2.5 times higher in the pathological shoulders.

CONCLUSIONS

With this technique the glenohumeral translation can be quantified three-dimensionally in functionally important positions and without projectional artefacts. In the future, this method can be applied to patients with different entities of shoulder instability.

Glenohumeral translation during active and passive elevation of the shoulder - a 3D open-MRI study

Despite its importance for the understanding of joint mechanics in healthy subjects and patients, there has been no three-dimensional (3D) in vivo data on the translation of the humeral head relative to the glenoid during abduction under controlled mechanical loading. The objective was therefore to analyze humeral head translation during passive and active elevation by applying an open MR technique and 3D digital postprocessing methods. Fifteen healthy volunteers were examined with an open MR system at different abduction positions under muscular relaxation (30-150 degrees of abduction) and during activity of shoulder muscles (60-120 degrees ). After segmentation and 3D reconstruction, the center of mass of the glenoid and the midpoint of the humeral head were determined and their relative position calculated. During passive elevation, the humeral head translated inferiorly from +1.58mm at 30 degrees to +0. 36mm at 150 degrees of abduction, and posteriorly from +1.55mm at 30 degrees to -0.07mm at 150 degrees of abduction. Muscular activity brought about significant changes in glenohumeral translation, the humeral head being in a more inferior position and more centered, particularly at 90 and 120 degrees of abduction (p<0.01). In anterior/posterior direction the humeral head was more centered at 60 and 90 degrees of abduction during muscle activity. The data demonstrate the importance of neuromuscular control in providing joint stability. The technique developed can also be used for investigating the effect of muscle dysfunction and their relevance on the mechanics of the shoulder joint.

[Magnetic resonance imaging of the wrist--comparison of high resolution pulse sequences and different fat signal suppression techniques in cadavers]

PURPOSE

To evaluate high resolution sequences with and without fat-suppression techniques for MR imaging of the wrist.

MATERIALS AND METHODS

10 cadaver wrist specimens were imaged with 12 MR sequences (SE: 400 ms/20 ms, TSE: 3000 ms/119 ms/17 ms, fatsat (FS) TSE: 3000 ms/17 ms and 3000 ms/45 ms, STIR: 2619 ms/29 ms/160 ms, DESS 3D: 43.7 ms/9 ms/35 degrees FS and 25.4 ms/9 ms/35 degrees water excitation (WE), CISS 3D: 12.2 ms/5.9 ms/40 degrees and FLASH-sequences: 53 ms/11 ms/40 degrees FS, 23 ms/11 ms/40 degrees WE and 45 ms/11 ms/30 degrees FS) at 1.5 T. Slice thickness was 3 mm, FOV 80 x 70 mm (pixel size 0.31 x 0.31 mm). Signal intensity was measured by an ROI in bone marrow, fluid, hyaline cartilage, scapholunate (SL) ligament and triangular fibrocartilage and S/N- and C/N-ratios were calculated. Additionally, a visual evaluation was performed.

RESULTS

The highest homogeneity and the least artifacts were achieved by the T1-w SE sequence. For the STIR and PD-FS TSE sequence high rankings were found for the detection of free water. The PD FS sequence had high ranking also for visualization of the SL ligament and the triangular fibrocartilage. The best sequence for the assessment of hyaline cartilage was the FLASH-FS sequence. For detailed analysis of bony structures the CISS sequence performed best.

CONCLUSION

The isolated use of a PD-FS-TSE sequence enables for evaluation of all clinically relevant structures at the wrist. Dedicated questions for hyaline cartilage are answered best by the use of a FLASH 3D-FS sequence. Selective water excitation reduces acquisition time to 60%, nevertheless FS sequences are still diagnostically superior to WE sequences.

Magnetic resonance-based motion analysis of the shoulder during elevation

Changes in shoulder motion patterns are relevant in various shoulder diseases, but no in vivo information exists about the relative positions in vivo of the shoulder girdle bones and the supraspinatus muscle in three-dimensional space. Thus, the objective of this study was to perform a motion analysis of these structures during passive arm elevation using open magnetic resonance imaging and three-dimensional image processing. Fourteen volunteers were examined in five positions of abduction (30 degrees-150 degrees) with an open magnetic resonance system. After segmentation and three-dimensional reconstruction, the axis of the supraspinatus, humerus, clavicle, and the plane of the glenoid were determined, and the relative movements were calculated. The ratio for glenohumeral to scapulothoracic motion was 1.5:1 at 60 degrees and 2.4:1 at 120 degrees abduction. At 30 degrees, the axis of the supraspinatus was nearly horizontal, and during abduction a continuous elevation (+123 degrees at 150 degrees abduction) was measured. In the transverse plane, the angle between the supraspinatus and the clavicle axes became larger during abduction because of an increasing retroversion of the clavicle. The study shows specific three-dimensional motion patterns for each bone of the shoulder girdle and the supraspinatus muscle during passive elevation. The technique and results can be used for future studies in patients with pathologic changes of shoulder girdle motion.

Effects of 780 nm diode laser irradiation on blood microcirculation: preliminary findings on time-dependent T1-weighted contrast-enhanced magnetic resonance imaging (MRI)

Laser therapy by low light doses shows promising results in the modulation of some cell functions. Various clinical studies indicate that laser therapy is a valuable method for pain treatment and the acceleration of wound healing. However, the mechanism behind it is still not completely understood. To explore the effect of a low-power diode laser (lambda = 780 nm) on normal skin tissue, time-dependent contrast enhancement has been determined by magnetic resonance imaging (MRI). In the examinations, six healthy volunteers (four male and two female) have been irradiated on their right planta pedis (sole of foot) with 5 J/cm2 at a fluence rate of 100 mW/cm2. T1-weighted magnetic resonance imaging is used to quantify the time-dependent local accumulation of Gadolinium-DPTA, its actual content in the local current blood volume as well as its distribution to the extracellular space. Images are obtained before and after the application of laser light. When laser light is applied the signal to noise ratio increases by more than 0.35 +/- 0.15 (range 0.23-0.63) after irradiation according to contrast-enhanced MRI. It can be observed that, after biomodulation with light of low energy and low power, wound healing improves and pain is reduced. This effect might be explained by an increased blood flow in this area. Therefore, the use of this kind of laser treatment might improve the outcome of other therapeutic modalities such as tumour ionizing radiation therapy and local chemotherapy.

Magnetic resonance imaging of lateral epicondylitis of the elbow with a 0.2-T dedicated system

The purpose of this study was to evaluate MR imaging findings of the common extensor tendon in patients with lateral epicondylitis and asymptomatic volunteers studied on a 0.2-T dedicated system. In 23 patients (age range 29-58 years, mean age 47 years) with clinical symptoms of lateral epicondylitis MR imaging was performed using T1-, T2- and contrast-enhanced T1-weighted spin-echo sequences. In addition, the elbows of seven healthy volunteers (age range 22-29 years, mean age 25 years) and the symptom-free contralateral elbow of 11 of the 23 patients (age range 29-58 years, mean age 47 years) were studied as controls. Five patients were surgically treated after the MR examination and the results of histopathology were correlated with MR findings. Of the patients, 95.6 % showed intratendinous signal intensity changes on T1-weighted images on the symptomatic side. In 69.6 % signal alterations were observed on T2-weighted sequences and in 56.5 % an intratendinous contrast enhancement was present. Histopathology showed fibrovascular proliferation and fatty degeneration in patients with distinct signal intensity changes and contrast enhancement. Patients with only minor signal intensity changes on T1- and T2-weighted sequences and no contrast enhancement demonstrated fibrosclerotic degeneration and intratendinous cartilage formation in histopathology. The contralateral elbow showed signal intensity changes in 6 of 11 (54.5 %) cases on T1-weighted images and in 3 of 11 (27.3 %) on T2-weighted images. In the group of healthy volunteers minor signal intensity changes of the common extensor tendon could be seen in only 1 case. In patients with lateral epicondylitis of the elbow the type and extent of pathologic changes within the common extensor tendon can be evaluated using a dedicated low-field MR system. On the basis of MR imaging findings a more specified therapy planning among the variety of treatment modalities can be achieved.

Subacromial space width changes during abduction and rotation--a 3-D MR imaging study

The objectives of this study were to determine systematic changes of the normal subacromial space width during abduction and rotation, and to analyze the spatial relationship of the supraspinatus muscle with the acromion and clavicle. 12 healthy volunteers were imaged by an open MR scanner in 5 different positions of abduction and in 3 positions of rotation. After three dimensional (3D) reconstruction and 3D Euclidian distance transformation, the minimal spatial distances between the humerus and the acromion and the humerus and clavicle were computed. The minimal acromio-humeral distance decreased significantly from 30 degrees of abduction (mean 7.0 mm +/- 1.6 mm) to 120 degrees (mean 3.9 mm; +/- 1.8 mm; p < 0.0001). At 30 degrees, the minimal distance penetrated the supraspinatus, whereas at 120 degrees it was always located lateral to the supraspinatus tendon. At 90 degrees with internal rotation (7.6 mm, +/- 2.3 mm) the minimal acromio-humeral distance was larger than in neutral rotation (5.4 mm, +/- 2.3 mm) or external rotation (4.4 mm, +/- 2.2 mm; p < 0.05), but it penetrated the supraspinatus tendon at its most vulnerable part, reaching the acromion at its anterior inferior border. We conclude that the subacromial space width changes during abduction and rotation and that the supraspinatus is in closest contact to the anterior inferior border of the acromion in 90 degrees of abduction with 45 degrees internal rotation. These values obtained in volunteers can be used as a basis for further investigations in patients with the impingement syndrome.

Three-dimensional analysis of the width of the subacromial space in healthy subjects and patients with impingement syndrome

OBJECTIVE

The aim of this study was to per form a three-dimensional analysis of the width of the subacromial space during passive and active arm abduction in healthy volunteers and patients with impingement syndrome.

SUBJECTS AND METHODS

The shoulders of 10 healthy subjects and 10 patients with impingement syndrome were imaged with an open MR system during abduction, with and without activation of the shoulder muscles. An apparatus was designed for applying an adduction force of 10 N to the distal humerus during image acquisition, and the minimal acromiohumeral distance was measured after three-dimensional reconstruction.

RESULTS

In the 10 healthy volunteers, muscle activity led to a significant decrease (-32%; p < .05) of the acromiohumeral distance at 60 degrees of abduction, whereas at 120 degrees of abduction the distance was significantly increased (+44%; p < .05). In these volunteers, muscle activation caused no significant effect at 90 degrees of abduction. However, in the 10 patients with impingement syndrome, muscle activity led to a significant decrease in the width of the subacromial space compared with that of the healthy contralateral side (-68%; p < .05).

CONCLUSION

Muscle activity and arm position were found to cause systematic changes in the width of the subacromial space. However, functional deficits of the supraspinous muscle in patients with early-stage impingement syndrome were not apparent during muscle relaxation.

[An MR-based technique for determination of the subacromial space width in subjects with and without shoulder muscle activity]

INTRODUCTION

The occurrence of the impingement syndrome of the shoulder is dependent on muscle activity and arm position. However, the current radiological workup is based on conventional radiographs, CT or MRI obtained at 0 degree of abduction and at muscular relaxation. The objective of this study was the development of a technique for simultaneous visualization of the humerus, scapula, clavicle and their relationship to the M. supraspinatus--in different arm abduction positions with and without muscle activity--as well as the determination of the minimal acromio-humeral distance.

METHOD

The shoulder joints of 8 volunteers were examined in an open MRI system at 60 degrees, 90 degrees and 120 degrees of abduction, using a T1 weighted 3D gradient echosequence. Forces of 10 N were applied at the distal humerus. After 3D reconstruction, the acromio-humeral distance was computed with Euclidian distance transformation.

RESULTS

With increasing abduction, the acromio-humeral distance decreased significantly (p < 0.05), but the distance vector was localised laterally to the M. supraspinatus at 120 degrees. With muscle activity a reduction of the subacromial space of 29% (p < 0.05) occurred at 60 degrees whereas at 120 degrees a 51% (p < 0.05) increase was noted. At 90 degrees, no significant difference was observed.

CONCLUSION

With the technique presented it is possible to determine the subacromial space width in different arm positions independent of the specific section orientation, with and without muscle activity. The method can be used as a basis for biomechanical investigations and for the clinical diagnosis of impingement syndrome.

A technique for determining the spatial relationship between the rotator cuff and the subacromial space in arm abduction using MRI and 3D image processing

An MR imaging-based technique for three-dimensional determination of subacromial space width in relation to the rotator cuff in arm abduction is presented. Five volunteers were examined in an open MRI in seven arm positions, and coronal images were obtained with a gradient-echo sequence. 3D reconstruction of the bones and the supraspinatus was performed, and the minimal spatial distances between acromion, clavicle, and humerus were calculated. The closest contact between the supraspinatus and the anterior inferior part of the acromion occurred at 90 degrees abduction in internal rotation. The technique presented allows investigation of the morphological basis of the impingement syndrome.

A comparison of pulse sequences in the detection of post-traumatic bone marrow abnormalities at low field strength MRI

OBJECTIVE AND PATIENTS

One hundred and forty-one patients with recent joint trauma, aged 12-71 years, were imaged on a 0.2-T dedicated MRI system and evaluated for bone bruises. The most beneficial sequences were compared.

DESIGN

The diagnosis of post-traumatic bone marrow abnormalities was established in 20 of 141 patients on the basis of decreased signal intensity on T1-weighted SE and GRE sequences and increased signal intensity on T2-weighted TSE and fat-suppressed IRGE sequences. Signal changes within the bone marrow were evaluated and statistically correlated with normal bone.

RESULTS

The highest signal alteration was found on T1-weighted SE and GRE sequences, followed by IRGE, which detected smaller differences in signal intensity. T2-weighted TSE imaging showed the least contrast. The areas with bone marrow changes were approximately equal in size on T1-weighted SE and T2-weighted TSE sequences. The same areas depicted on IRGE and GRE sequences proved to be significantly larger (P < 0.01).

CONCLUSION

Using a 0.2-T dedicated system T1-weighted SE, T1-weighted GRE and IRGE sequences were most effective in detecting conspicuous bone marrow alteration, while the T2-weighted TSE sequence was inferior. GRE and IRGE imaging showed areas about 4 times larger depicting bone marrow changes. On suspicion of bone bruise, a protocol including GRE and IRGE pulse sequences could be most beneficial.