ARRS Case of the Week- Oct 23, 2017

From http://www.arrs.org/ARRSLIVE/CaseOfTheWeek.

CARDIOVASCULAR IMAGING: Coronary Arteries

Case Author: Rachna Madan, MD, Brigham and Women’s Hospital

History

62-year-old man with hypertension, atypical chest pain, and perfusion scintigraphic finding of mild apical ischemia.

Imaging Findings

Axial (A), curved planar (B), and short-axis (C) reformatted ECG-gated coronary angiograms reconstructed at 75% of the R-R interval show a lesion at the mid left anterior descending artery. Curved planar reformatted (D) and short-axis (E) images at the same level reconstructed at 85% of the R-R interval show the same lesion.

Calcified atherosclerotic plaque causing complete occlusion
Mixed atherosclerotic plaque causing complete occlusion
Pseudostenosis as result of artifact

Diagnosis

Pseudostenosis as result of artifact

Teaching Points

Despite proper preparation, artifacts and scan noise can occur, usually caused by cardiac or respiratory motion and obesity. These artifacts can cause errors during interpretation or can make a scan nondiagnostic, exposing the patient to radiation and iodinated contrast material without benefit. Misregistration artifacts are produced by arrhythmia, respiratory motion, problems with ECG gating, and limitations of temporal resolution. They are best recognized when slice misalignments are seen in the coronal or sagittal plane. If motion is subtle, small hypodense amorphous areas are noted in the periphery of the vessel. These artifacts are difficult to overcome at postprocessing. Artifacts related to ECG gating can be resolved during reading of images obtained in other phases of reconstruction or by ECG editing. Banding artifacts occur when information is missed because of bradycardia or after a ventricular ectopy pause. The remedy for this kind of problem is ECG editing (i.e., reconstruction of additional areas in the prolonged R-R interval, also known as synchs).

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