Simultaneous bilateral magnetic resonance angiography to evaluate thoracic outlet syndrome

Crossed raised arm position improves the flow of contrast medium in torso contrast-enhanced computed Tomography

INTRODUCTION

This retrospective cohort study examined the effects of the crossed raised arm (CRA) position in contrast-enhanced computed tomography (CECT) on contrast medium influx and image quality relative to the conventional position.

METHODS

Contrast medium influx into the collateral veins on CECT images was evaluated in 92 participants. The CT values of the pulmonary artery, descending aorta, and spleen were obtained in both positions and compared. Anatomical changes in the diameters and area of the subclavian vein and costoclavicular distance were also analyzed.

RESULTS

Contras 27 and 6 patients in the conventional and CRA positions, respectively. The influx risk ratio in the CRA position versus that in the conventional position was 0.22 (95% confidence interval, 0.10-0.51). Elevations in the median CT value of the pulmonary artery, descending aorta, and spleen in the CRA position were 7.0% (p < .001), 7.4% (p < .001), and 9.8% (p < .001), respectively. Enlargements in the major and minor diameters of the subclavian vein, subclavian vein area, and costoclavicular distance in the CRA position versus those in the conventional position were 19.3% (p < .001), 28.1% (p < .001), 53.6%, and 30.0% (p < .001), respectively.

CONCLUSION

The CRA position effectively prevented contrast medium influx into the collateral veins due to SVS and increased CT values in the target organs in CECT. The diameters and area of the subclavian vein and costoclavicular distance were enlarged at the thoracic outlet, which improved the flow of the contrast medium into the targeted organs.

IMPLICATIONS FOR PRACTICE

The CRA position can contribute to obtaining better CECT images during common clinical assessments at no additional cost.

ACR Appropriateness Criteria® Thoracic Outlet Syndrome

Thoracic outlet syndrome (TOS) is the clinical entity that occurs with compression of the brachial plexus, subclavian artery, and/or subclavian vein at the superior thoracic outlet. Compression of each of these structures results in characteristic symptoms divided into three variants: neurogenic TOS, venous TOS, and arterial TOS, each arising from the specific structure that is compressed. The constellation of symptoms in each patient may vary, and patients may have more than one symptom simultaneously. Understanding the various anatomic spaces, causes of narrowing, and resulting neurovascular changes is important in choosing and interpreting radiological imaging performed to help diagnose TOS and plan for intervention. This publication has separated imaging appropriateness based on neurogenic, venous, or arterial symptoms, acknowledging that some patients may present with combined symptoms that may require more than one study to fully resolve. Additionally, in the postoperative setting, new symptoms may arise altering the need for specific imaging as compared to preoperative evaluation. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Thoracic Outlet Syndrome: Diagnostic Accuracy of MRI

BACKGROUND

Thoracic outlet syndrome (TOS) is challenging to diagnose, as the physical findings and investigations lack sensitivity and/or specificity. Magnetic resonance imaging (MRI) with dynamic manoeuvres can rule out a tumour and detect anatomical abnormalities potentially responsible for compression. The objective of this study was to assess the sensitivity and specificity of MRI for identifying anatomical structures responsible for compression in TOS, using intra-operative findings as the diagnostic reference standard.

HYPOTHESIS

MRI is effective in diagnosing the source of compression in TOS, notably within the scalene triangle and at the pleural apex.

METHODS

We retrospectively included 48 patients who underwent surgery for TOS after a work-up that included MRI (1.5-T, n=29 and 3-T, n=19). The MRI scans were reviewed for the study by a specialised radiologist who was unaware of the intra-operative findings. The sensitivity and specificity of MRI for diagnosing TOS were estimated using the intra-operative findings as the reference standard.

RESULTS

MRI identified a structure potentially responsible for TOS in 34 (71%) patients; thus, the false-negative rate was 14/48 (29%). The sensitivity of MRI was 28% for compression at the suspensory ligament of the pleural dome, 81% for hypertrophy of the anterior scalene muscle, and 50% for an accessory scalene muscle. For diagnosing a cervical rib, MRI had 100% sensitivity and 100% specificity.

CONCLUSION

MRI can contribute to the diagnosis of TOS. Specificity is sufficiently high to provide guidance for planning the surgical procedure. Sensitivity, however, is too low for MRI to be useful as a screening test. MRI should be used in combination with the clinical assessment and other investigations to assist in the diagnosis of TOS.

LEVEL OF EVIDENCE

IV, retrospective cohort study.

Thoracic outlet syndrome in a postoperative cervical spondylotic myelopathy patient: A case report

RATIONALE

Thoracic outlet syndrome (TOS) is a rare disease that presents with neurogenic and vascular symptoms similar to those of cervical spondylosis. However, making the diagnosis of TOS can be challenging due to a lack of standardized objective confirmatory tests.

PATIENT CONCERNS

A 66-year-old man presented with neck, supraclavicular, and right shoulder pain as well as numbness and weakness in the right arm after surgery to correct cervical spondylotic myelopathy (CSM).

DIAGNOSIS

Magnetic resonance imaging confirmed the diagnosis of CSM. He was diagnosed with TOS based on the manifestations and examination findings.

INTERVENTIONS

After surgery for CSM, nonoperative management was provided.

OUTCOMES

The patient reported pain relief and improving sensation in the shoulder and supraclavicular region.

LESSONS

Based on this case and the reviewed literature, to optimize the diagnosis and treatment of CSM, clinicians should consider preoperative differential diagnosis to preliminarily exclude it.

Ultrasonographic Identification of Fibromuscular Bands Associated with Neurogenic Thoracic Outlet Syndrome: The "Wedge-Sickle" Sign

Thoracic outlet syndrome (TOS) is a disorder characterized by compression of the lower trunk of the brachial plexus, most often in association with anomalous congenital fibromuscular bands in the scalenic region. Early diagnosis is important, because the neurologic deficit associated with TOS may be irreversible. Using high-resolution ultrasound, we investigated 20 consecutive patients with clinical signs suggestive of TOS (all females, average age: 40.4 ± 14.9 y) and 25 control patients. In 19 patients, we identified a hyper-echoic fibromuscular structure at the medial edge of the middle scalene muscle, which indented the lower trunk of the brachial plexus ("wedge-sickle sign"). It was associated with the significant enlargement (p < 0.0001) and hypo-echogenicity of the lower trunk. This novel and distinctive ultrasonographic sign allows pre-surgical identification of anomalous fibromuscular bands causing TOS. It is especially useful in patients without neurologic deficit, in whom the diagnosis may not be as straightforward.