Non-enhanced MR angiography of renal arteries: comparison with contrast-enhanced MR angiography

BACKGROUND

The main causes of renal artery stenosis (RAS) are atherosclerosis and fibromuscular dysplasia. Despite contrast-enhanced magnetic resonance angiography (CE-MRA) being a safe and reliable method for diagnosis of RAS especially in young individuals, recently it has been possible to adopt innovative technologies that do not require paramagnetic contrast agents.

PURPOSE

To assess the accuracy of steady-state free-precession (SSFP) non-contrast-enhanced magnetic resonance angiography (NC-MRA) by using a 1.5 T MR scanner for the detection of renal artery stenosis, in comparison with breath-hold CE-MRA as the reference standard.

MATERIAL AND METHODS

Sixty-three patients (33 men, 30 women) with suspected renovascular hypertension (RVHT) were examined by a 1.5T MR scanner; NC-MRA with an electrocardiography (ECG)-gated SSFP sequence was performed in 58.7% (37/63) of patients; in 41.3% (26/63) of patients a respiratory trigger was used in addition to cardiac gating. CE-MRA, with a three-dimensional gradient echo (3D-GRE) T1-weighted sequence, was performed in all patients within the same session. Maximum intensity projection (MIP) image quality, number of renal arteries, and the presence of stenosis were assessed by two observers (independently for NC-MRA and together for CE-MRA). The agreement between NC-MRA and CE-MRA as well as the inter-observer reproducibility were calculated with Bland-Altman plots.

RESULTS

MIP image quality was considered better for NC-MRA. NC-MRA identified 143 of 144 (99.3%) arteries detected by CE-MRA (an accessory artery was not identified). Fourteen stenoses were detected by CE-MRA (11 atherosclerotic, 3 dysplastic) with four of 14 (28.5%) significant stenosis. Bland-Altman plot demonstrated an excellent concordance between NC-MRA and CE-MRA; particularly, the reader A evaluated correctly all investigated arteries, while over-estimation of two stenoses occurred for reader B. Regarding NC-MRA, inter-observer agreement was excellent.

CONCLUSION

NC-MRA is a valid alternative to CE-MRA for the assessment of renal arteries.

Long head of the biceps tendon and rotator interval

The term "biceps brachii" is a Latin phrase meaning "two-headed (muscle) of the arm." As its name suggests, this muscle has two separate origins. The short head of biceps is extraarticular in location, originates from the coracoid process of the scapula, having a common tendon with the coracobrachialis muscle. The long head of biceps tendon (LBT) has a much more complex course, having an intracapsular and an extracapsular portion. The LBT originates from the supraglenoid tubercle, and in part, from the glenoid labrum; the main labral attachments vary arising from the posterior, the anterior of both aspects of the superior labrum (Bletran et al. in Top Magn Reson Imaging 14:35-49, 2003; Vangsness et al. in J Bone Joint Surg Br 76:951-954, 1994). Before entering the bicipital groove (extracapsular portion), the LBT passes across the "rotator cuff interval" (intracapsular portion). Lesions of the pulley system, the LBT, and the supraspinatus tendon, as well as the subscapularis, are commonly associated (Valadie et al. in J Should Elbow Surg 9:36-46, 2000). The pulley lesion can be caused by trauma or degenerative changes (LeHuec et al. in J Should Elbow Surg 5:41-46, 1996). MR arthrography appears to be a promising imaging modality for evaluation of the biceps pulley, through the distention of the capsule of the rotator interval space and depiction of the associated ligaments.

Ankle impingement: a review of multimodality imaging approach

Ankle impingement is defined as entrapment of an anatomic structure that leads to pain and decreased range of motion of the ankle and can be classified as either soft tissue or osseous (Bassett et al. in J Bone Joint Surg Am 72:55-59, 1990). The impingement syndromes of the ankle are a group of painful disorders that limit full range of movement. Symptoms are due to compression of soft-tissues or osseous structures during particular movements (Ogilvie-Harris et al. in Arthroscopy 13:564-574, 1997). Osseous impingement can result from spur formation along the anterior margin of the distal tibia and talus or as a result of a prominent posterolateral talar process, the os trigonum. Soft-tissue impingement usually results from scarring and fibrosis associated with synovial, capsular, or ligamentous injury. Soft-tissue impingement most often occurs in the anterolateral gutter, the medial ankle, or in the region of the syndesmosis (Van den Bekerom and Raven in Knee Surg Sports Traumatol Arthrosc 15:465-471, 2007). The main impingement syndromes are anterolateral, anterior, anteromedial, posterior, and posteromedial impingement. These conditions arise from initial ankle injuries, which, in the subacute or chronic situation, lead to development of abnormal osseous and soft-tissue thickening within the ankle joint. The relative contributions of the osseous and soft-tissue abnormalities are variable, but whatever component is dominant there is physical impingement and painful limitation of ankle movement. Conventional radiography is usually the first imaging technique performer and allows assessment of any potential bone abnormality, particularly in anterior and posterior impingement. Computed tomography (CT) and isotope bone scanning have been largely superseded by magnetic resonance (MR) imaging. MR imaging can demonstrate osseous and soft-tissue edema in anterior or posterior impingement. MR imaging is the most useful imaging modality in evaluating suspected soft-tissue impingement or in excluding other ankle pathology such as an osteochondral lesion of the talus. MR imaging can reveal evidence of previous ligamentous injury and also can demonstrate thickened synovium, fibrosis, or adjacent reactive soft-tissue edema. Studies of conventional MR imaging have produced conflicting sensitivities and specificities in assessment of anterolateral impingement. CT and MR arthrographic techniques allow the most accurate assessment of the capsular recesses, albeit with important limitations in diagnosis of clinical impingement syndromes. In the majority of cases, ankle impingement is treated with conservative measures, with surgical debridement via arthroscopy or an open procedure reserved for patients who have refractory symptoms. In this article, we describe the clinical and potential imaging features, for the four main impingement syndromes of the ankle: anterolateral, anterior, anteromedial, posterior, and posteromedial impingement.

Lesions of the rotator cuff footprint: diagnostic performance of MR arthrography compared with arthroscopy

BACKGROUND

To evaluate the diagnostic performance of magnetic resonance arthrography (MR-A) of the shoulder in the diagnosis of rotator cuff tears involving the humeral insertion of the supraspinatus and infraspinatus tendon (footprint), using arthroscopy as the reference standard.

MATERIALS AND METHODS

The study population included 90 consecutive patients with history and clinical diagnosis of instability of the shoulder, rotator cuff tear or posterosuperior glenoid impingement. A total of 108 MR arthrograms were performed, since 18 patients had undergone a bilateral procedure. Arthroscopy, which was performed within 45 days after MR-A, was used as the reference standard. Sensitivity, specificity, accuracy, positive and negative predictive values were then calculated.

RESULTS

Magnetic resonance arthrography showed a sensitivity of 92 % and a specificity of 78 % for the overall detection of tears involving the rotator cuff footprint. The diagnostic accuracy was 90 %, and the positive and negative predictive values were 95 and 64 %, respectively. Ten lesions were non-classifiable on surgery, of which eight were non-classifiable on MR-A also.

CONCLUSIONS

Magnetic resonance arthrography is extremely accurate for the detection and classification of rotator cuff footprint tears. Most of these lesions are articular-sided (partial articular-sided supraspinatus tendon avulsion lesions) with predominance in younger patients and concealed type of tear (concealed interstitial delamination lesions).

Diagnostic imaging of ankle impingement syndromes in athletes

The chronic ankle pain is a very frequent clinical problem, which is often characterized by a painful mechanical limitation of full-range ankle movement. A large amount of causes are involved in its pathogenesis, but the most common forms are secondary to an osseous or soft tissue abnormality. Especially for professional athletes, impingement lesions are the most important causes of chronic pain; however, this symptomatology can also affect ordinary people, mostly in those who work in environments that cause severe mechanical stress on the joints. This group of pathologies is characterized by a joint conflict secondary to an abnormal contact among bone surfaces or between bones and soft tissues. Diagnosis is mainly clinic and secondly supported by imaging in order to localize the critical area of impingement and determine the organic cause responsible for the joint conflict. Treatments for different forms of impingement are similar. Usually, the first step is a conservative approach (rest, physiotherapy, ankle bracing, shoe modification and local injection of corticosteroids), and only in case of unsuccessful response, the second step is the operative treatment with open and arthroscopic techniques. The aim of the study is to describe different MR imaging patterns, comparing our data with those reported in the literature, in order to identify the best accurate diagnostic protocol.

Mechanism of traumatic knee injuries and MRI findings

Bone bruises are focal abnormalities in subchondral bone marrow due to trabecular microfractures as a result of traumatic force. These trauma-induced lesions are better detected with magnetic resonance (MR) imaging using water-sensitive sequences. Moreover, the pattern of bone bruise is distinctive and allows us to understand the dynamics of trauma and to predict associated soft injuries. This article discusses the mechanism of traumatic injury and MR findings.

Contrast enhanced ultrasound with second generation contrast agent for the follow-up of lower-extremity muscle-strain-repairing processes in professional athletes

PURPOSE

In literature, ultrasonographic potentials in traumatic muscle lesions have been codified, whereas the data about this method utility in follow-up are dissonant. The purpose of this work is to evaluate a second-generation ultrasound (US) contrast agent rule for the professional athletes' distractive lesions.

MATERIALS AND METHODS

Twenty professional athletes (18 men and two women, aged between 18 and 34 years) affected by different muscle lesions were examined. All the patients were evaluated within 48 h of the trauma by US device Esaote Technos MPX with a high-frequency linear probe. The examinations were carried out with and without contrast agent after 20, 40 and 60 days after the trauma; second-generation contrast agent was used (SonoVue).

RESULTS

In all athletes (nine first-grade lesions, 11 second-grade lesions), by using contrast agent intravenous injection done after 20 days, the appearance of contrast spots affecting part or all the lesioned area were observed. During the follow-up, after 40 days. the contrast spots widened to include the entire scar area, with haemorrhagic residual in three cases. After 60 days, in no case was a liquid haemorrhagic collection still present, and we found an important reduction of extension of vascular spots and US intensity and their total disappearance in seven cases.

CONCLUSIONS

US with a second-generation contrast agent, thanks to the neoangiogenesis identification, allows recognition, individuation and monitoring the repair processes in the muscle lesion and allows estimation of when athletes can return to competitive activity. This fact obviously reduces both relapses and complications.