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Contrast Enhanced MRA Enhances Diagnosis Of Head And Neck Paraganglioma

June 2, 2009
Written by: , Filed in: Neuroradiology
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The objective of a recent study was to evaluate the use of elliptic centric contrast-enhanced magnetic resonance angiography (CE-MRA) in detection of neck paragangliomas compared with conventional MRI.

The results of the study show that contrast enhanced MRA demonstrated 100% sensitivity and significantly improved specificity over conventional MR in evaluation of head and neck paragangliomas and distinguishing them from other lesions.

Participants
27 consecutive patients over a 4-year period referred for MRI evaluation of known or suspected paragangliomas participated in the study.

Methodology
1.5T MR was performed with 4-mm T1 SE, T2 FSE, fat suppressed T1 SE axial, and coronal images from proximal to carotid bifurcation to skull base.

Coronal CE-MRA from aortic arch to skull base was obtained with 1.4-mm thick images.

Images were reformatted into maximum intensity projection (MIP) and multiplanar reconstruction (MPR) projections.

Three head and neck radiologists analyzed the images for quality, location of lesions, and probability of paraganglioma (probable, uncertain, or improbable).

Criteria for conventional MR diagnosis were typical location, displacement pattern of adjacent vessels, presence of flow voids, and “salt and pepper” appearance.

Criteria for MRA were similar, but more significant were early and intense enhancement similar to arterial vascular enhancement.

Neuroradiology Review

The Johns Hopkins University School of Medicine
Course Directors: David Yousem, MD, MBA and Doris Lin, MD, PhD Maintaining certification requires not only medical knowledge to deliver quality care but also other essential elements that must be developed and maintained throughout every radiologist’s career. Therefore, this program serves as a comprehensive review of neuro-radiology and prepares the participants to tackle imaging of the brain, spine, head and neck, as well as the vascular anatomy of the central nervous system. Click here to read more or order: Neuroradiology Review

Results
46 lesions were identified in 27 patients; 34 were paragangliomas present in 20 patients in typical locations plus 1 retrothyroid, and 1 thoracic lesion. Four were postoperative residual paragangliomas.

Conventional imaging demonstrated 10 false-positive results (5 probable, 5 uncertain). These consisted of 1 meningioma, 1 plasmacytoma, 4 reactive lymphadenopathies, 2 schwannomas, 1 dural arteriovenous fistula, and 1 postoperative scar. Three paragangliomas were classified as uncertain.

Flow voids were detected in 30 of 32 paragangliomas; 5 other tumors showed flow voids as well.

CE-MRA had significantly superior specificity over conventional MR (94% vs 41%). MRA was superior in sensitivity (100%), positive predictive value, and negative predictive value, but these differences were not statistically significant.

There were 21 uncertain findings on conventional MR, 17 of which were correctly diagnosed on MRA. Fifteen uncertain cases on MRA were present, of which only 4 could be correctly diagnosed on conventional imaging.

The larger field of view of CE-MRA allowed detection of 2 paragangliomas missed on conventional imaging (1 in the superior mediastinum and 1 in a retrothyroid position).

Conclusions
CE-MRA is more specific than conventional MRI in evaluating paragangliomas and distinguishing them from other lesions. It should be used routinely in evaluating for the possibility of this diagnosis.

Reviewer’s Comments
This well-done, clearly written study had convincing results. Only specificity was statistically significantly different, but improved specificity is the most important use of MRA, since the sensitivity is 100%.

These figures also depend on whether uncertain findings are classified as positive or negative.

A potential pitfall is other vascular tumors such as renal cell carcinoma metastases, which could mimic paraganglioma but were not present in the study group.

Author: Yaron Lebovitz, MD

Reference:

Neves F, Huwart L, et al. Head and Neck Paragangliomas: Value of Contrast-Enhanced 3D MR Angiography. AJNR; 2008; 29 (May): 883-889

Neuroradiology Review

The Johns Hopkins University School of Medicine
Course Directors: David Yousem, MD, MBA and Doris Lin, MD, PhD Maintaining certification requires not only medical knowledge to deliver quality care but also other essential elements that must be developed and maintained throughout every radiologist’s career. Therefore, this program serves as a comprehensive review of neuro-radiology and prepares the participants to tackle imaging of the brain, spine, head and neck, as well as the vascular anatomy of the central nervous system. Click here to read more or order: Neuroradiology Review
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