Internal Impingement of the Shoulder: A Risk of False Positive Test Outcomes in External Impingement Tests?

BACKGROUND: External impingement tests are considered as being particularly reliable for identifying subacromial and coracoid shoulder impingement mechanisms. The purpose of the present study was to evaluate if these tests are likely to provoke an internal shoulder impingement mechanism which, in cases of a pathologic condition, can lead to a positive test result. METHOD: In 37 subjects, the mechanical contact between the glenoid rim and the rotator cuff (RC) was measured quantitatively and qualitatively in external impingement test positions using an open MRI system. RESULTS: Mechanical contact of the supraspinatus with the posterosuperior glenoid was present in 30 subjects in the Neer test. In the Hawkins test, the subscapularis was in contact with the anterosuperior glenoid in 33 subjects and the supraspinatus in 18. In the horizontal impingement test, anterosuperior contact of the supraspinatus with the glenoid was identified in 35 subjects. CONCLUSION: The Neer, Hawkins, and horizontal impingement tests are likely to provoke the mechanism of an internal shoulder impingement. A posterosuperior internal impingement mechanism is being provoked predominately in the Neer test. The Hawkins test narrows the distance between the insertions of the subscapularis and supraspinatus and the anterosuperior labrum, which leads to an anterosuperior impingement mechanism.

In vivo analysis of coracoid and subacromial shoulder impingement mechanism during clinical examination.

BACKGROUND: Understanding the mechanisms of shoulder impingement created by clinical tests is crucial to accurately evaluate the condition. The objective of this study was to relate mechanisms of subacromial and coracoid impingement occurring in positions of the shoulder during clinical examination, in quantitative and qualitative terms. METHODS: A 1.0T open magnetic resonance imaging system was used in 18 female and 19 male subjects, to determine the distances between the humeral head and the acromion or coracoid, and contact with the rotator cuff (RC). Measurements were taken with the shoulder in neutral, "Hawkins", "Neer", and 90° abduction/15° internal rotation (horizontal impingement test) positions. Additionally, impingement was classified based on the grade of RC contact with the acromion or coracoid. RESULTS: In the Hawkins position, distance between the supraspinatus and the coracoid was closest (14.5 ± 4.5 mm), while the coracohumeral distance (CHD) narrowed (p < 0.001). In the horizontal impingement test position, the minimum distance between the subscapularis and coracoid was found, whereas the CHD increased (27.4 ± 5.7 mm). In the Neer and Hawkins positions, the space between the greater tuberosity and acromion was significantly narrowed, which was also the case in the horizontal impingement test position compared to neutral position (p < 0.001). CONCLUSION: Shoulder movements of forward flexion and internal rotation (Hawkins test) and abduction and internal rotation (horizontal impingement test) can lead to different coracoid impingement mechanisms during clinical examination. The Hawkins, Neer, and horizontal impingement tests lead to comparable narrowed acromiohumeral distances and subacromial contact of the RC. LEVEL OF EVIDENCE: Therapeutic level III.

Muscular forces affect the glycosaminoglycan content of joint cartilage: unloading in human volunteers with the HEPHAISTOS lower leg orthosis.

BACKGROUND AND PURPOSE: Unloading alters the thickness of joint cartilage. It is unknown, however, to what extent unloading leads to a loss of glycosaminoglycans (GAGs) in the cartilage tissue. We hypothesized that muscle forces, in addition to axial loading, are necessary to maintain the joint cartilage GAG content of the knee and the upper and lower ankle. PATIENTS AND METHODS: The HEPHAISTOS orthosis was worn unilaterally by 11 men (mean age 31 (23-50) years old) for 56 days. The orthosis reduces activation and force production of the calf muscles while it permits full gravitational loading of the lower leg. MRI measurements of the knee and ankle were taken before the intervention, during the intervention (on day 49), and 14 days after the end of the intervention. Cartilage segmentation was conducted semiautomatically for the knee joint (4 segments) and for the upper (tibio-talar) and lower (subtalar) ankle joints (2 segments each). Linear mixed-effects (LME) models were used for statistical analysis. RESULTS: 8 volunteers completed the MRI experiment. In the lower ankle joint, differences in ΔT1 were found between the end of the intervention and 14 days after (p = 0.004), indicating a decrease in GAG content after reloading. There were no statistically significant differences in ΔT1 values in the knee and upper ankle joints. INTERPRETATION: Our findings suggest that in addition to gravitational load, muscular forces affect cartilage composition depending on the local distribution of forces in the joints affected by muscle contraction.

Assessment of lumbar intervertebral disc glycosaminoglycan content by gadolinium-enhanced MRI before and after 21-days of head-down-tilt bedrest.

During spaceflight, it has been shown that intervertebral discs (IVDs) increase in height, causing elongation of the spine up to several centimeters. Astronauts frequently report dull lower back pain that is most likely of discogenic origin and may result from IVD expansion. It is unknown whether disc volume solely increases by water influx, or if the content of glycosaminoglycans also changes in microgravity. Aim of this pilot study was to investigate effects of the spaceflight analog of bedrest on the glycosaminoglycan content of human lumbar IVDs. Five healthy, non-smoking, male human subjects of European descent were immobilized in 6° head-down-tilt bedrest for 21 days. Subjects remained in bed 24 h a day with at least one shoulder on the mattress. Magnetic Resonance Imaging (MRI) scans were taken according to the delayed gadolinium-enhanced magnetic resonance imaging (dGEMRIC) protocol before and after bedrest. The outcome measures were T1 and ΔT1. Scans were performed before and after administration of the contrast agent Gd-DOTA, and differences between T1-values of both scans (ΔT1) were computed. ΔT1 is the longitudinal relaxation time in the tissue and inversely related to the glycosaminoglycan-content. For data analysis, IVDs L1/2 to L4/5 were semi-automatically segmented. Zones were defined and analyzed separately. Results show a highly significant decrease in ΔT1 (p<0.001) after bedrest in all IVDs, and in all areas of the IVDs. The ΔT1-decrease was most prominent in the nucleus pulposus and in L4/5, and was expressed slightly more in the posterior than anterior IVD. Unexpected negative ΔT1-values were found in Pfirrmann-grade 2-discs after bedrest. Significantly lower T1 before contrast agent application was found after bedrest compared to before bedrest. According to the dGEMRIC-literature, the decrease in ΔT1 may be interpreted as an increase in glycosaminoglycans in healthy IVDs during bedrest. This interpretation seems contradictory to previous findings in IVD unloading.

Supplemental screening ultrasound increases cancer detection yield in BRCA1 and BRCA2 mutation carriers.

INTRODUCTION: This study aimed at evaluating the efficacy of ultrasound for the early detection of breast cancers in BRCA1/2 mutation carriers. METHODS: Between 01/1997 and 10/2008 221 BRCA1/2 mutation carriers participated in a breast cancer screening program which included semi-annual ultrasound in combination with annual mammography and magnetic resonance imaging (MRI). Women underwent on average (median) five semi-annual screening rounds with a range of one to 22 appointments, totaling 1,855 rounds of screening. All three imaging modalities were coded according to the American College of Radiology (BI-RADS classification). RESULTS: In total, we detected 27 BRCA-associated breast cancers in 25 patients. The sensitivity was 77% for ultrasound, 27% for mammography, and 100% for MRI. Three tumors were detected directly as a result of only the semi-annual ultrasound screen. CONCLUSIONS: Due to the specific tumor morphology and the considerably elevated tumor doubling time, mutation carriers benefit from the addition of semi-annual ultrasound screening as a sensitive and cost-effective method.

Transmurality of scar influences the effect of a hybrid-intervention with autologous bone marrow cell injection and aortocoronary bypass surgery (MNC/CABG) in patients after myocardial infarction.

BACKGROUND: Cell therapy (CTx) is a strategy to support cardiac regeneration after myocardial infarction (MI). Thus far, clinical studies provided mixed results. Here, we investigated whether transmurality of the infarct may play a relevant role. METHODS: 18 patients (63 ± 3 years, 15 male) undergoing elective coronary artery bypass graft (CABG) surgery 2.2 ± 0.7 months post MI participated. 10 had transmural and 8 non-transmural infarct scars assessed by Tc-99m-MIBI Single-Photon Emission Computed Tomography (SPECT) and F18-FDG-Positron-Emission-Tomography (PET). During surgery, 10 ml of sternal bone marrow were obtained, mononuclear cells (MNC) were isolated. At the end of surgery MNC were injected into the infarctions' center and border zones (10 injections, 2 ml total, 6.6 ± 1.3 × 10(7) MNC). RESULTS: No major complications attributable to cell therapy were observed. The sizes of non-transmural scars were reduced at 3 and 24 months after treatment (7.7 ± 1.1% and 5.5 ± 1.8 vs. 17.5 ± 4.9%, P=0.05 and P=0.04), while transmural scars remained unchanged (23.5 ± 2.6% and 23.8±3.2 vs. 23.5 ± 2.6%, P>0.99 and P=0.95). A trend towards improved LVEF was seen in patients with non-transmural scars (MRI: 48.8 ± 5.1% vs. 30.6 ± 8.7%, P=0.3; SPECT: 54.1 ± 3.1 vs. 41.0 ± 4.0, P=0.086), but not in patients with transmural scars (MRI: 36.7 ± 3.9 vs. 34.3 ± 5.0, P=0.63, SPECT: 37.8 ± 3.1 vs. 37.9 ± 2.3%, P=0.96). CONCLUSIONS: A single hybrid intervention of MNC recovery, purification and injection with CABG-surgery (MNC/CABG) may be an attractive modality for cell therapy. However, no regeneration of avital transmural scar tissue seems to occur, while the contribution of MNC to improved perfusion in non-transmural myocardial infarct scars remains to be determined.

Stabilization of the femoral head with a gliding screw in slipped capital femoral epiphysis.

OBJECTIVE: In situ fixation of the proximal femoral epiphysis to prevent further dislocation while maintaining the potential for longitudinal growth by insertion of a central gliding screw. Prevention of secondary coxarthrosis. INDICATIONS: Incipient and imminent slipped capital femoral epiphysis in children with a displacement angle of < 30 degrees in the axial view (ET' < 30 degrees ) and prophylactic treatment of the contralateral side. CONTRAINDICATIONS: Allergies to implant materials. SURGICAL TECHNIQUE: A Kirschner wire is inserted through a lateral proximal approach in the femur into the center of the displaced epiphysis at a right angle to its base. Overdrilling of the wire, thread tapping in the cancellous bone, insertion of the cannulated gliding screw with washer. The screw threads lie only in the epiphysis. The unthreaded part of the screw bridges the growth plate. The screw is allowed to protrude by about 2.5 cm to prevent an epiphyseodesis effect. POSTOPERATIVE MANAGEMENT: Partial weight bearing of the affected extremity up to 10 kg body weight for 6 weeks. Thrombosis prophylaxis during convalescence only for adolescents with signs of puberty (menarche/pubarche). Restriction on sports activities for 3 months. Follow-ups: clinical and radiologic examinations at 3 months postoperatively, then clinical examination every 6 months and radiologic assessment annually (possibly earlier, if there is a growth spurt). The gliding screw is removed when growth is completed. RESULTS: 63 hips (34 prophylactically and 29 therapeutically) were stabilized with the gliding screw. Clinically, the prophylactically stabilized hips showed excellent outcomes; of the therapeutically stabilized hips, the results were 19 excellent, seven good, two satisfactory, and one poor. Differences in leg length were seen in five cases, whereby the average value was 0.3 cm (0-1 cm). Chondrolysis or femoral head necrosis was not observed. Screw revision was necessary in 22 cases because contact between the screw head and the cortex would have prevented continued longitudinal growth (unintentional epiphyseodesis).

Strategy for safe performance of extrathoracic magnetic resonance imaging at 1.5 tesla in the presence of cardiac pacemakers in non-pacemaker-dependent patients: a prospective study with 115 examinations.

BACKGROUND: The purpose of the present study was to evaluate a strategy for safe performance of extrathoracic magnetic resonance imaging (MRI) in non-pacemaker-dependent patients with cardiac pacemakers. METHODS AND RESULTS: Inclusion criteria were presence of a cardiac pacemaker and urgent clinical need for an MRI examination. Pacemaker-dependent patients and those requiring examinations of the thoracic region were excluded. The study group consisted of 82 pacemaker patients who underwent a total of 115 MRI examinations at 1.5T. To minimize radiofrequency-related lead heating, the specific absorption rate was limited to 1.5 W/kg. All pacemakers were reprogrammed before MRI: If heart rate was <60 bpm, the asynchronous mode was programmed to avoid magnetic resonance (MR)-induced inhibition; if heart rate was >60 bpm, sense-only mode was used to avoid MR-induced competitive pacing and potential proarrhythmia. Patients were monitored with ECG and pulse oximetry. All pacemakers were interrogated immediately before and after the MRI examination and after 3 months, including measurement of pacing capture threshold (PCT) and serum troponin I levels. All MR examinations were completed safely. Inhibition of pacemaker output or induction of arrhythmias was not observed. PCT increased significantly from pre- to post-MRI (P=0.017). In 2 of 195 leads, an increase in PCT was only detected at follow-up. In 4 of 114 examinations, troponin increased from a normal baseline value to above normal after MRI, and in 1 case (troponin pre-MRI 0.02 ng/mL, post-MRI 0.16 ng/mL), this increase was associated with a significant increase in PCT. CONCLUSIONS: Extrathoracic MRI of non-pacemaker-dependent patients can be performed with an acceptable risk-benefit ratio under controlled conditions and by taking both MR- and pacemaker-related precautions.

Cerebral diffusion-weighted magnetic resonance imaging: a tool to monitor the thrombogenicity of left atrial catheter ablation.

INTRODUCTION: Cerebral embolism and stroke are feared complications of left atrial catheter ablation such as pulmonary vein (PV) ablation. In order to assess the thrombogenicity of left atrial catheter ablation, knowledge of both clinically evident as well as silent cerebral embolism is important. The aim of the current study was to examine the use of diffusion-weighted magnetic resonance imaging (DW-MRI) for detection of cerebral embolism, apparent as well as silent, caused by PV catheter ablation. METHODS AND RESULTS: Twenty consecutive patients without structural heart disease undergoing lasso catheter-guided ostial PV ablation using an irrigated-tip ablation catheter were studied. Cerebral MRI including DW single-shot spin echo echoplanar, turbo fluid attenuated inversion recovery, and T2-weighted turbo spin echo sequences were performed the day after the ablation procedure. Ten patients also underwent preprocedure cerebral MRI. All ablation procedures were performed without acute complications. A mean of 3.2 +/- 0.6 PVs were ablated per patient. No patient had neurological symptoms following the procedure. In 2 of 20 patients (10%), DW-MRI revealed new embolic lesions, which were located in the right periventricular white matter in one and in the left temporal lobe in the other patient. There was no statistically significant difference in age, history of hypertension, left atrial volume, and procedure duration between the 2 patients with and the 18 patients without cerebral embolism following AF ablation. CONCLUSION: This is the first study using highly sensitive DW-MRI of the brain to detect asymptomatic cerebral embolism after left atrial catheter ablation. Even small, clinically silent, embolic lesions can be demonstrated with this technique. DW-MRI can be used to monitor and compare the thrombogenicity of different AF ablation approaches.

Coronary MR angiography at 3.0 T versus that at 1.5 T: initial results in patients suspected of having coronary artery disease.

PURPOSE: To prospectively evaluate the feasibility, image quality, and accuracy of coronary magnetic resonance (MR) angiography at 3.0 T in patients suspected of having coronary artery disease and to prospectively compare these results with those of coronary MR angiography performed at 1.5 T. MATERIALS AND METHODS: The study was approved by the institutional review board, and informed consent was obtained from all patients. Eighteen patients (11 men, seven women; mean age, 63 years; age range, 45-76 years) suspected of having coronary artery disease who were scheduled to undergo elective conventional coronary angiography (reference standard) were included. For coronary MR angiography at 3.0 and 1.5 T, a vector electrocardiographically gated three-dimensional segmented k-space gradient-echo imaging sequence was combined with real-time respiratory navigator gating and tracking. Signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), scores of image quality and sensitivity and specificity for the detection of coronary artery stenosis on a segment-by-segment basis were assessed at 3.0 and 1.5 T. Data were analyzed for statistical differences by using the Wilcoxon matched-pairs test and the McNemar test. RESULTS: The average increase in SNR at 3.0 T with respect to that at 1.5 T was 29.5% for the left coronary artery (LCA) and 31.2% for the right coronary artery (RCA) (P < .001), and the average increase in CNR was 21.8% for the LCA and 23.5% for the RCA (P < .001). Scores of image quality (P = .77) and diagnostic accuracy for the detection of coronary artery stenoses (sensitivity and specificity: 82% and 89%, respectively, at 3.0 T vs 82% and 88% at 1.5 T; P > .99) were identical or almost identical at both field strengths. CONCLUSION: Coronary MR angiography at 3.0 T is feasible in patients suspected of having coronary artery disease and yields significant increases in SNR and CNR, although current techniques do not result in significantly improved image quality and diagnostic accuracy compared with the quality and accuracy at 1.5 T. (c) RSNA, 2005.

Relationship between size of myocardial infarctions assessed by delayed contrast-enhanced MRI after primary PCI, biochemical markers, and time to intervention.

BACKGROUND: The quantitative assessment of myocardial infarctions using delayed contrast-enhanced magnetic resonance imaging (MRI) has recently been validated using postmortem histopathological animal studies. In a prospective study, we investigated the correlation between infarct size as assessed by delayed contrast-enhanced MRI, elevation of creatine kinase (CK), and c-reactive protein (CRP) as well as the time from onset of symptoms to intervention. METHODS: Four to 10 days after immediate PCI in 45 acute ST-segment elevation myocardial infarction (STEMI) patients (<24 hour) with stenting of the infarct-related artery and treatment with abciximab, we performed gadolinium contrast-enhanced three-dimensional inversion recovery gradient-echo MR sequences with complete coverage of the LV-myocardium in short-axis slices. The mass of infarcted tissue based on the volume of hyperenhanced myocardium was calculated and linear regression analysis was performed to assess the correlation between absolute size of infarctions (g) as well as relative size (LV%) with peak values of CK, CRP, and the time to PCI. RESULTS: There was a significant correlation between absolute size of infarctions (g) and peak CK values (r = 0.72; P < 0.001) as well as the relative size (LV%) and peak CK (r = 0.77; P < 0.001). No correlations were found between absolute size (r = 0.33) as well as relative size (r = 0.27) of infarctions and peak CRP. There was also no correlation between absolute (r = 0.29) as well as relative size of infarctions (r = 0.27) and the time from onset of symptoms to PCI. CONCLUSIONS: In patients with acute STEMI (<24 hour) undergoing immediate PCI with stenting and treatment with abciximab, peak CK values correlated well with infarct size as assessed by delayed contrast-enhanced MRI. There were no correlations between infarct size and peak CRP as well as the time to intervention.

Fate of left atrial thrombi in patients with atrial fibrillation determined by transesophageal echocardiography and cerebral magnetic resonance imaging.

Patients with atrial fibrillation (AF) and atrial thrombi have an increased risk for cerebral embolism. However, there is little knowledge about the long-term fate of atrial thrombi and the incidence of cerebral embolism in patients receiving continued oral anticoagulation. Forty-three consecutive patients with AF and atrial thrombi were enrolled in the study. Serial and prospective transesophageal echocardiographic studies, cranial magnetic resonance imaging (MRI), and clinical examinations were performed during a period of 12 months. Oral anticoagulation was continued or initiated in all patients. An international normalized ratio of 2.0 to 3.0 was regarded as effective. During follow-up, 56% of the thrombi disappeared (7 [16%] at 1 month, 18 [42%] at 3 months, 21 [49%] at 6 months, and 24 [56%] at 12 months). Patients with the disappearance of thrombi had significantly smaller thrombi compared with patients with persistent thrombi (1.5 +/- 0.8 cm in length and 0.8 +/- 0.5 cm in width vs 1.9 +/- 0.6 cm in length and 1.3 +/- 0.4 cm in width, p = 0.04), reduced echogenicity of thrombi (46% vs 89%, p <0.01), and smaller left atrial (LA) volume (83 +/- 27 vs 116 +/- 55 cm(3)). Seven patients (16%) had embolic lesions during follow-up MRI. Six of these patients (86%) had clinically apparent embolisms, and 1 died from stroke. The only independent predictors of cerebral embolism were an elevated peak emptying velocity of the LA appendage (p <0.01) and previous thromboembolic events (p = 0.02). Patients with AF and atrial thrombi have a large likelihood of cerebral embolism (16%) and/or death despite oral anticoagulation therapy. Thrombus size may predict thrombus resolution under continued anticoagulation.

Silent and apparent cerebral embolism after retrograde catheterisation of the aortic valve in valvular stenosis: a prospective, randomised study.

BACKGROUND: In most patients, severity of valvular aortic stenosis can be accurately assessed non-invasively by echocardiography. However, retrograde catheterisation of the aortic valve is often undertaken. This procedure has a potential risk of neurological complications, with an unknown incidence of clinically silent embolism. We aimed to establish the frequency of clinically apparent and silent cerebral embolism after this procedure. METHODS: We prospectively randomised 152 consecutive patients with valvular aortic stenosis at a German university hospital to receive either cardiac catheterisation with (n=101) or without (n=51) passage through the aortic valve. Patients underwent cranial MRI and neurological assessment within 48 h before and after the procedure to assess cerebral embolism. Controls were 32 patients without valvular aortic stenosis who underwent coronary angiography and laevocardiography. FINDINGS: 22 of 101 patients (22%) who underwent retrograde catheterisation of the aortic valve had focal diffusion-imaging abnormalities in a pattern consistent with acute cerebral embolic events after the procedure; three of these patients (3%) had clinically apparent neurological deficits. By contrast, none of the patients without passage of the valve, or any of the controls, had evidence of cerebral embolism as assessed by MRI. INTERPRETATION: Patients with valvular aortic stenosis who undergo retrograde catheterisation of the aortic valve have a substantial risk of clinically apparent cerebral embolism, and frequently have silent ischaemic brain lesions. Patients should be informed about these risks, and this procedure should be used only in patients with unclear echocardiographical findings when additional information is necessary for clinical management.