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The authors performed a retrospective, observational, cross-sectional study to assess the prevalence and characteristic features of cerebellar heterotopias in 35 patients with CHARGE syndrome with available brain MR imaging studies, as well as to evaluate additional features of cerebellar dysgenesis. Cerebellar heterotopias were identified in 27/35 (77%) patients with CHARGE, characteristic in both location and appearance. Additional features of cerebellar dysgenesis were present in 31/34 evaluable patients (91%), including inferior vermian hypoplasia (90%), anteromedial rotation of the inferior tonsils (90%), and disorganized foliation of the cerebellar hemispheres (74%) or superior vermis (16%). Patients with CHARGE syndrome have a high prevalence of characteristic cerebellar heterotopias.

Projection data from 83 patients undergoing unenhanced spiral head CT for suspected neurologic deficits were collected. A routine dose was obtained using 250 effective mAs and iterative reconstruction. Lower-dose configurations were reconstructed (25-effective mAs iterative reconstruction, 50-effective mAs filtered back-projection and iterative reconstruction, 100-effective mAs filtered back-projection and iterative reconstruction, 200-effective mAs filtered back-projection). Three neuroradiologists circled findings, indicating diagnosis, confidence, and image quality. The routine-dose jackknife alternative free-response receiver operating characteristic figure of merit was 0.87. Noninferiority was shown for 100-effective mAs iterative reconstruction and 200-effective mAs filtered back-projection, but not for100-effective mAs filtered back-projection. The authors conclude that substantial opportunity exists for dose reduction using spiral nonenhanced head CT and that the dose level might potentially be reduced to 40% of routine dose levels or a volume CT dose index of approximately 15mGy if slight decreases in performance are acceptable. The beneficial effect of iterative reconstrution was most pronounced at this 15-mGy dose level.