Water content changes in new multiple sclerosis lesions have a minimal effect on the determination of myelin water fraction values.

BACKGROUND AND PURPOSE: Myelin water fraction (MWF) is a histopathologically validated in vivo myelin marker. As MWF is the proportion of water with a short T2 relative to the total water, increases in water from edema and inflammation may confound MWF determination in multiple sclerosis (MS) lesions. Total water content (TWC) measurement enables calculation of absolute myelin water content (MWC) and can be used to distinguish edema/inflammation from demyelination. We assessed what influence changes in total water might have on MWF by calculating MWC values in new MS lesions. METHODS: 3T 32-echo T2 relaxation data were collected monthly for 6 months from six relapsing-remitting MS participants. TWC was determined and multiplied with MWF images to calculate corrected MWC images. The effect of this water content correction was examined in 20 new lesions by comparing mean MWF and MWC over time. RESULTS: On average, at lesion first appearance, lesion TWC increased by 6.4% (p = .003; range: -1% to +21%), MWF decreased by 24% (p = .006; range: -70% to +12%), and MWC decreased by 20% (p = .026; range: -68% to +21%), relative to prelesion values. Average TWC in lesions then gradually decreased, whereas MWF and MWC remained low. The shape of the MWF and MWC lesion evolution curves was nearly identical, differing only by an offset. CONCLUSION: MWF mirrors MWC and is able to monitor myelin in new lesions. Even after taking into account water content increases, MWC still decreased at lesion first appearance attributed to demyelination.

AN ANALYSIS OF THE QUALITY OF THYROID CANCER WEBSITES.

Objective: This study evaluated online thyroid cancer patient information quality. This is essential, given increasing patient use of online health information. Methods: A total of 100 thyroid cancer websites, representing those patients find first, were identified using Google and two meta-search engines. Content accuracy and patient-evaluable quality markers, including attribution, currency, structure, and content comprehensiveness and readability, were assessed with a previously validated standardized rating tool, developed using design-based methods. Accuracy was defined compared to standard, peer-reviewed medical resources, UpToDate and the National Comprehensive Cancer Network. Responses to general and personal "patient" questions were evaluated for promptness and accuracy. Results: Of 100 websites, only 26% stated authorship, and 56% cited sources. Seventy-four percent had dates of creation or last update, with only half of those dates occurring within the past 2 years. Websites most often discussed the definition (94%), diagnosis (92%), and treatment (94%) of thyroid cancer, but diagnosis and treatment were also most frequently incomplete or inaccurate: diagnosis information was complete and accurate 50% of the time, and treatment 47%. Only 2% of websites were comprehensible without high school education. Of 83 websites contacted with "patient" questions, 50 replied, 48 within 1 week. Conclusion: Thyroid cancer information is widely available online, but quality varies. Sites often lack markers for patients to assess quality, and content may be difficult to understand. Information is frequently incomplete, particularly on topics important to patients, such as diagnosis and treatment. Educational resource developers may fill these gaps, and healthcare providers can direct thyroid cancer patients to reliable online resources. Abbreviation: NCCN = National Comprehensive Cancer Network.

The physical mechanism of "inhomogeneous" magnetization transfer MRI.

Inhomogeneous MT (ihMT) is a new magnetic resonance imaging technique that shows promise for myelin selectivity. Materials with a high proportion of lipids, such as white matter tissue, show a reduced intensity in magnetic resonance images acquired with selective prepulses at positive and negative offsets simultaneously compared to images with a single positive or negative offset prepulse of the same power. This effect was initially explained on the basis of hole-burning in inhomogeneously broadened lines of the lipid proton spin system. Our results contradict this explanation. ihMT in lipids can be understood with a simple spin-1 model of a coupled methylene proton pair. More generally, Provotorov theory can be used to consider the evolution of dipolar order in the non-aqueous spins during the prepulses. We show that the flip-angle dependence of the proton spectrum of a model lipid system (Prolipid-161) following dipolar order generation is in quantitative agreement with the model. In addition, we directly observe dipolar order and ihMT signals in the non-aqueous components of Prolipid-161 and homogeneously-broadened systems (hair, wood, and tendon) following ihMT prepulses. The observation of ihMT signals in tendon suggests that the technique may not be as specific to myelin as previously thought. Our work shows that ihMT occurs because of dipolar couplings alone, not from a specific type of spectral line broadening as its name suggests.