Identifying perfusion deficits on CT perfusion images using temporal similarity perfusion (TSP) mapping.

OBJECTIVES: Deconvolution-derived maps of CT perfusion (CTP) data may be confounded by transit delays. We propose temporal similarity perfusion (TSP) analysis to decrease CTP maps' dependence on transit times and investigate its sensitivity to detect perfusion deficits. METHODS: CTP data of acute stroke patients obtained within 9 h of symptom onset was analyzed using a delay-insensitive singular value decomposition method and with TSP. The TSP method applies an iterative process whereby a pixel's highest Pearson's R value is obtained through comparison of a pixel's time-shifted signal density time-series curve and the average whole brain signal density time-series curve. Our evaluation included a qualitative and quantitative rating of deconvolution maps (MTT, CBV, and TTP), of TSP maps, and of follow-up CT. RESULTS: Sixty-five patients (mean 68 (SD 13) years, 34 male) were included. A perfusion deficit was identified in 90%, 86%, 65%, and 84% of MTT, TTP, CBV, and TSP maps. The agreement of MTT, TTP, and TSP with CT follow-up was comparable but noticeably lower for CBV. CBV had the best relationship with final infarct volume (R2 = 0.77, p < 0.001), followed by TSP (R2 = 0.63, p < 0.001). Intra-rater agreement of an inexperienced reader was higher for TSP than for CBV/MTT maps (kappa's of 0.79-0.84 and 0.63-0.7). Inter-rater agreement for experienced readers was comparable across maps. CONCLUSIONS: TSP maps are easier to interpret for inexperienced readers. Perfusion deficits detected by TSP are smaller which may suggest less dependence on transit delays although more investigation is required. KEY POINTS: • Temporal similarity perfusion mapping assesses CTP data based on similarities in signal time-curves. • TSP maps are comparable in perfusion deficit detection to deconvolution maps. • TSP maps are easier to interpret for inexperienced readers.

Grade of dysplasia and malignant transformation in adults with premalignant laryngeal lesions.

BACKGROUND: The purpose of this systematic review was to determine the significance of the grade of dysplasia in the development of invasive carcinoma. METHODS: A systematic search was performed to identify all relevant evidence. Titles and abstracts were screened using predefined criteria. Remaining articles were critically appraised. Absolute risks and 95% confidence intervals (CIs) were calculated. RESULTS: Seven articles were included. Four studies demonstrated an increased risk for the development of laryngeal carcinoma from mild, moderate, and severe dysplasia. Three studies showed an increased risk between the categories of mild and moderate dysplasia. CONCLUSION: The risk of malignant transformation seems to increase with the grade of dysplasia, although percentages between studies are highly dissimilar. The wide variety and overlapping 95% CIs make it difficult to formulate a strong recommendation. However, moderate dysplasia is more prone for malignant transformation than previously thought, which might influence follow-up and treatment decisions in the future. © 2015 Wiley Periodicals, Head Neck 38: E2284-E2290, 2016.