Prabhakar Rajiah MD, FRCR, Presenter: Nothing to Disclose

Randolph M. Setser DSc, Abstract Co-Author: Nothing to Disclose

Samer Sayyed, Abstract Co-Author: Nothing to Disclose

Milind Desai, Abstract Co-Author: Nothing to Disclose

Scott Daniel Flamm MD, Abstract Co-Author: Research grant, Koninklijke Philips Electronics NV Research grant, Siemens AG Medical Advisory Board, Vital Images, Inc Consultant, TeraRecon, Inc

Presence of scar in hypertrophic cardiomyopathy (HCM) is an important adverse prognostic determinant. However, quantification of scar in HCM is challenging due to its patchy and heterogeneous nature. The purpose of this study was to compare several existing scar quantification techniques in patients with HCM.

A retrospective analysis was performed on 44 consecutive HCM patients. All scans were performed on 1.5 T MRI scanner (Philips, Best, The Netherlands) and scar was quantified using prototype software (Philips). Scar was quantified by two blinded readers using ten techniques, all previously described in the literature: Visual threshold determination, threshold defined as 1 to 7 standard deviations (SD) above the mean signal intensity (SI) of remote viable myocardium, threshold defined as the peak SI of remote myocardium, and threshold defined as 50% of maximal SI of enhanced area (full-width at half maximum, FWHM).

Delayed enhancement was present in 25 (57%) patients. There was wide variation in the scar volume among techniques. By visual technique, scarred LV myocardium averaged 24 ± 17%. The 3SD (25 ± 19%, p=0.55) and FWHM (25 ± 18%, p=0.75) techniques did not differ significantly from visual; all other techniques differed significantly. There was good inter-observer agreement, with no significant differences between readers for any of the techniques, except when the threshold was defined as the peak SI of remote myocardium.

The full-width at half maximum technique and a threshold of 3 SD above the mean SI of the remote myocardium provided the best agreement with visual assessment and minimal inter-observer variability.The two currently used techniques of 2 SD and 6SD above the peak SI of remote myocardium appear to over and underestimate the scar volume, respectively.

In hypertrophic cardiomyopathy, scar quantification, when performed, should use FWHM or a threshold of 3SD above the mean SI of remote myocardium.

Rajiah, P, Setser, R, Sayyed, S, Desai, M, Flamm, S, Quantification of Scar in Hypertrophic Cardiomyopathy by Various Techniques—An MR Imaging Study.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9001800.html