Coronary Stent Artifact Reduction with an Edge-Enhancing Reconstruction Kernel - A Prospective Cross-Sectional Study with 256-Slice CT.

PURPOSE: Metallic artifacts can result in an artificial thickening of the coronary stent wall which can significantly impair computed tomography (CT) imaging in patients with coronary stents. The objective of this study is to assess in vivo visualization of coronary stent wall and lumen with an edge-enhancing CT reconstruction kernel, as compared to a standard kernel. METHODS: This is a prospective cross-sectional study involving the assessment of 71 coronary stents (24 patients), with blinded observers. After 256-slice CT angiography, image reconstruction was done with medium-smooth and edge-enhancing kernels. Stent wall thickness was measured with both orthogonal and circumference methods, averaging thickness from diameter and circumference measurements, respectively. Image quality was assessed quantitatively using objective parameters (noise, signal to noise (SNR) and contrast to noise (CNR) ratios), as well as visually using a 5-point Likert scale. RESULTS: Stent wall thickness was decreased with the edge-enhancing kernel in comparison to the standard kernel, either with the orthogonal (0.97 ± 0.02 versus 1.09 ± 0.03 mm, respectively; p<0.001) or the circumference method (1.13 ± 0.02 versus 1.21 ± 0.02 mm, respectively; p = 0.001). The edge-enhancing kernel generated less overestimation from nominal thickness compared to the standard kernel, both with the orthogonal (0.89 ± 0.19 versus 1.00 ± 0.26 mm, respectively; p<0.001) and the circumference (1.06 ± 0.26 versus 1.13 ± 0.31 mm, respectively; p = 0.005) methods. The edge-enhancing kernel was associated with lower SNR and CNR, as well as higher background noise (all p < 0.001), in comparison to the medium-smooth kernel. Stent visual scores were higher with the edge-enhancing kernel (p<0.001). CONCLUSION: In vivo 256-slice CT assessment of coronary stents shows that the edge-enhancing CT reconstruction kernel generates thinner stent walls, less overestimation from nominal thickness, and better image quality scores than the standard kernel.

256-slice CT angiographic evaluation of coronary artery bypass grafts: effect of heart rate, heart rate variability and Z-axis location on image quality.

PURPOSE: The objective of this study is to assess the effect of heart rate, heart rate variability and z-axis location on coronary artery bypass graft (CABG) image quality using a 256-slice computed tomography (CT) scanner. METHODS: A total of 78 patients with 254 CABG (762 graft segments) were recruited to undergo CABG assessment with 256-slice CT and prospective ECG-gating. Two observers rated graft segments for image quality on a 5-point scale. Quantitative measurements were also made. Logistic and cumulative link mixed models were used to assess the predictors of graft image quality. RESULTS: Graft image quality was judged as diagnostic (scores 5 (excellent), 4 (good) and 3 (moderate)) in 96.6% of the 762 segments. Interobserver agreement was excellent (kappa ≥0.90). Graft image quality was not affected by heart rate level. However, high heart rate variability was associated with an important and significant image quality deterioration (odds ratio 4.31; p  =  0.036). Distal graft segments had significantly lower image quality scores than proximal segments (p ≤ 0.02). Significantly higher noise was noted at the origin of the mammary grafts (p  =  0.001), owing to streak artifacts from the shoulders. CONCLUSION: CABG imaging with 270-msec rotation 256-slice CT and prospective ECG-gating showed an adequate image quality in 96.6% of graft segments, and an excellent interobserver agreement. Graft image quality was not influenced by heart rate level. Image quality scores were however significantly decreased in patients with high heart rate variability, as well as in distal graft segments, which are closer to the heart.

Postoperative imaging after lung transplantation.

Lung transplantation (LT) is an established procedure for chronic end-stage lung diseases. Complications are frequent and diverse and are the consequence of the complex surgical technique, the severity of the initial pathology, and the deep state of posttransplantation immunosuppression. Complications following LT include primary graft dysfunction, rejection (hyperacute, acute, and chronic), infections, posttransplantation lymphoproliferative disease, pleural and airway complications, native lung complications, and recurrence of primary disease. An understanding of these complications, their temporal evolution, and the role of radiology and other diagnostic methods in their diagnosis and management will help reduce the morbidity and mortality associated with LT.

Dual-energy x-ray absorptiometry in the diagnosis of osteoporosis: a practical guide.

OBJECTIVE: The purpose of this essay is a quick and comprehensive review of dual-energy x-ray absorptiometry in the diagnosis of osteoporosis that shows how to achieve the best performance in three steps. CONCLUSION: The three-step procedure for dual-energy x-ray absorptiometry includes image acquisition emphasizing proper patient positioning and regions of interest; analysis, including areas to scan and detection of artifacts that should be excluded from the analysis and noted in the report because they can necessitate additional imaging; and interpretation of results.

Role of multidetector CT in the management of acute female pelvic disease.

The purpose of this study is to highlight the role of multidetector CT (MDCT) in emergency radiology as a useful tool in the diagnosis and management of acute female pelvic disease and to describe key radiologic signs to improve differential diagnosis. We restrospectively reviewed MDCT findings of acute pelvic disease and its mimics in women reporting to the emergency room at our institution from December 2006 to August 2008. We describe MDCT findings of gynecologic and obstetric disorders such as hemorrhagic ovarian cysts, ovarian torsion, pelvic inflammatory disease, ruptured ectopic pregnancy, intravascular leiomyomatosis, blunt maternal trauma, and postpartum and post-cesarean section complications. We also briefly review gastrointestinal tract entities that may mimic these conditions. Although ultrasound is the imaging modality of choice for the evaluation of female pelvic pain, the role of MDCT remains essential in the management of patients in which gynecologic exploration is not diagnostic or undone since it is not the initial suspicion.