Editor’s and Fellows’ Journal Club Choices, May 2008

Editor’s Choices

The Leptomeningeal “Ivy Sign” on Fluid-Attenuated Inversion Recovery MR Imaging in Moyamoya Disease: A Sign of Decreased Cerebral Vascular Reserve? • N. Mori, S. Mugikura, S. Higano, T. Kaneta, M. Fujimura, A. Umetsu, T. Murata, and S. Takahashi
The “ivy” sign refers to increased pial and sulcal signal intensity in patients with Moyamoya disease. We know this sign is due to collateral circulation and these authors investigated the utility of the finding by reassessing it in MR studies in 48 patients with this disease. They divided the brains into 4 different regions and correlated the presence of the ivy sign in MR imaging with findings obtained by single-photon emission CT, including cerebral blood flow and cerebral vascular reserve. In their results, the degree of the ivy sign correlated with ischemic symptoms and was more prominent frontally. The ivy sign showed negative relationships with both CBF and CVR. The authors concluded the presence of this sign in Moyamoya disease indicates decreased CVR.

Multidetector Row CT Angiography in Spontaneous Lobar Intracerebral Hemorrhage: A Prospective Comparison with Conventional Angiography • D.Y. Yoon, S.K. Chang, C.S. Choi, W.-K. Kim, and J.-H. Lee
Depending on age and underlying clinical factors, some patients with spontaneous lobar intracerebral hemorrhages will need a vascular study to exclude a causative lesion. Most of these patients are eventually evaluated with digital catheter angiography. In this study, the authors used multidetector CT to obtain CT angiography in 78 such patients. The original data, reformations, and volume-rendered images were assessed blindly. Underlying lesions were shown in 22 patients, with the most common being aneurysms, arteriovenous malformations, and Moyamoya disease. Overall sensitivity, specificity, positive and negative predictive values were very high for CTA in this situation and the authors concluded it is a highly accurate technique for the diagnosis of underlying vascular lesions in patients with spontaneous cerebral hemorrhages.

Diagnostic Accuracy of the Constructive Interference in Steady State Sequence Alone for Follow-Up Imaging of Vestibular Schwannomas • B. Ozgen, B. Oguz, and A. Dolgun
We all know of the utility of constructive interference in steady state images in the initial diagnosis of vestibular schwannoma and use these on a routine clinical basis for this purpose. Similarly, all of us prefer contrast-enhanced MR imaging studies in patients who have been previously operated on for these tumors. In this article, the authors evaluated the diagnostic accuracy of CISS in the latter set of patients. Up to 5 follow-up studies in 18 patients were assessed for mass size and progression. The sensitivity, specificity, and accuracy of CISS were 100%. CISS evaluation for the internal features of the masses was limited. The authors concluded CISS may be a viable alternative to contrast-enhanced MR imaging studies in this clinical setting, something to keep in mind when gadolinium is contraindicated.

Fellows’ Journal Club

Relative Decrease in Signal Intensity of Subcortical White Matter in Spontaneous Intracranial Hypotension on Fluid-Attenuated Inversion Recovery Images • M. Adachi, S. Mugikura, A. Shibata, E. Kawaguchi, T. Sato, and S. Takahashi
In patients with chronic headaches, spontaneous intracranial hypotension is being entertained more frequently by neuroradiologists and neurologists but continues to be difficult to diagnose with certainty and to treat. In this article, the authors sought to evaluate a different sign: a relative decrease in signal intensity in the subcortical white matter. They retrospectively reviewed T2 and fluid-attenuated inversion recovery images in 10 patients looking for this finding. The evaluation was both a subjective and a quantitative one. The lower signal was evident on FLAIR both visually and quantitatively but not on T2-weighted images. The authors concluded this low signal in white matter may be another sign that may help in making this diagnosis.

Normal Findings on Brain Fluid-Attenuated Inversion Recovery MR Images at 3T • M. Neema, Z.D. Guss, J.M. Stankiewicz, A. Arora, B.C. Healy, and R. Bakshi
Artifacts on FLAIR brain sequences occur frequently and consistently and have been addressed on images obtained at 1.5T. In this retrospective study, the authors assessed these artifacts found in FLAIR images obtained at 3T and compared them with findings at 1.5T. Most subjects underwent imaging at both field strengths. The most common sites for the artifacts were: periventricular, posterior white matter, septum pellucidum, corticospinal tracts, and ventricular CSF. Number and signal intensity were higher at 3T, whereas size was similar at both field strengths. This article reminds us of how common these artifacts are and that it is important to recognize and not confuse these with true lesions.

Symptomatic Nerve Root Changes on Contrast-Enhanced MR Imaging after Surgery for Lumbar Disk Herniation • Y.S. Lee, E.S. Choi, and C.J. Song
Nerve root contrast enhancement due to alterations in the root-blood barrier is common in both non-operated and postsurgical patients and tends to correlate with pain. These authors evaluated postoperative patients with recurrent symptoms and nerve root contrast enhancement to assess any association between the two. They studied 140 operated disk levels and correlated these with presence of recurrent disk herniations and epidural scar formation. Nearly 60% showed nerve root enhancement with 91.7% sensitivity, 73% specificity, and 84% positive predictive value. Nerve root enhancement, thickening, and displacement were most significantly associated with pain. Of these, nerve root enhancement was the most striking.

Editor’s and Fellows’ Journal Club Choices, May 2008