Jesse Habets MD, Presenter: Nothing to Disclose

Petr Symersky MD, Abstract Co-Author: Nothing to Disclose

Willem P. Mali MD, PhD, Abstract Co-Author: Nothing to Disclose

Bas De Mol MD, PhD, Abstract Co-Author: Nothing to Disclose

Tim Leiner MD, PhD, Abstract Co-Author: Speakers Bureau, Koninklijke Philips Electronics NV Research grant, Bayer AG Research grant, Bracco Group

Ricardo P.J. Budde MD, PhD, Abstract Co-Author: Nothing to Disclose

Multidetector-row CT is promising for prosthetic heart valve (PHV) assessment but retrospectively ECG-gated scanning has a considerable radiation dose. Recently introduced iterative reconstruction (IR) algorithms may enable radiation dose reduction with retained image quality. Our purpose was to compare image noise and artifact volumes in scans of mechanical PHVs reconstructed with conventional filtered back projection (FBP) to lower dose scans reconstructed with IR.

Four different PHV’s (St. Jude, Carbomedics, ON-X and Medtronic Hall) were scanned in a pulsatile in vitro model. Ten retrospectively ECG-gated CT scans were performed of each PHV at 120 KV, 600 mAs (high-dose CTDIvol 35.3mGy) and 120 KV, 300 mAs (low-dose CTDIvol 17.7mGy) on a 64 detector-row scanner. Diastolic and systolic images were reconstructed with FBP (high and low-dose) and the IR algorithm (low-dose only). Hypo- and hyperdense artifact volumes were determined using two threshold filters. Image noise was measured.

Mean image noise was 16.3±1.6 HU (high-dose scan FBP), 23.2±2.3 HU (low-dose scan FBP) and 16.5±1.7 (low-dose scan IR). Low-dose IR reconstructions had similar image noise compared to high-dose FBP (16.5±1.7 vs. 16.3±1.6, mean ± SD, respectively, p=1.0). Mean hypo- and hyperdense artifact volumes (mm3) were 1235/5346 (high-dose FBP); 2405/6877 (low-dose FBP) and 1218/5333 (low-dose IR). For all PHV types, hypodense artifact volumes were similar for the high-dose scans reconstructed with FBP when compared to low-dose scans reconstructed with IR(ON-X PHV’s p=0.55 and other PHV’s p=1.0, respectively). Hyperdense artifacts were similar for the high-dose scans reconstructed with FBP when compared to low-dose scans reconstructed with IR (St Jude p=0.95, all other valves p=1.0).

Iterative reconstruction allows ECG-gated PHV imaging with similar image noise and PHV artifacts at 50% less dose compared to conventional filtered back projection in an in vitro pulsatile model.

Iterative reconstruction is a promising method that allows low-dose prosthetic heart valve imaging.

Habets, J, Symersky, P, Mali, W, De Mol, B, Leiner, T, Budde, R, A Novel Iterative Reconstruction Algorithm Allows Reduced Dose Multidetector-row CT Imaging of Mechanical Prosthetic Heart Valves.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11004476.html