No abstract

To determine the diagnostic performance and reproducibility of strain assessment with displacement encoding with stimulated echoes (DENSE) cardiovascular magnetic resonance (CMR) in identifying contractile abnormalities in myocardial segments with late gadolinium enhancement (LGE). DENSE CMR was obtained on short-axis planes of the left ventricle (LV) in 24 patients with suspected coronary artery disease. e1 and e2 strains of LV wall were quantified. Cine MRI was acquired to determine percent systolic wall thickening (%SWT), followed by (LGE) CMR. The diagnostic performance of e1, e2 and %SWT for predicting the presence of LGE was evaluated by receiver operating characteristics (ROC) analysis. Myocardial scar on LGE CMR was observed in 91 (24 %) of 384 segments. The area under ROC curve for predicting the segments with LGE was 0.874 by e1, 0.916 by e2 and 0.828 by %SWT (p = 0.001 between e2 and %SWT). Excellent inter-observer reproducibility was found for strain [Intraclass correlation coefficient (ICC) = 0.962 for e1, 0.955 for e2] as compared with %SWT (ICC = 0.790). DENSE CMR can be performed as a part of routine CMR study and allows for quantification of myocardial strain with high inter-observer reproducibility. Myocardial strain, especially e2 is useful in detecting altered abnormal systolic contraction in the segments with myocardial scar.

This study evaluated the safety, feasibility, and clinical utility of hyaluronic acid gel injection to separate the gastrointestinal tract from the tumor during liver radiofrequency ablation (RFA). Eleven patients with liver tumors measuring 0.9-3.5 cm (mean ± standard deviation, 2.1 ± 0.8 cm) that were adjacent to the gastrointestinal tracts received RFA after the mixture of hyaluronic acid gel and contrast material (volume, 26.4 ± 14.5 mL; range, 10-60 mL) was injected between the tumor and the gastrointestinal tract under computed tomographic-fluoroscopic guidance. Each tumor was separated from the gastrointestinal tract by 1.0-1.5 cm (distance, 1.2 ± 0.2 cm) after injection of hyaluronic acid gel, and subsequent RFA was performed without any complications in all patients. Although tumor enhancement disappeared in all patients, local tumor progression was found in a patient (9.1%, 1 of 11) during the follow-up of 5.5 ± 3.2 months (range, 0.4-9.9 months). In conclusion, hyaluronic acid gel injection is a safe and useful technique to avoid thermal injury of the adjacent gastrointestinal tract during liver RFA.

SummaryThe aim of this study was to investigate the relationship between partial electrical reset (PER) and CT scan parameters (tube voltage, tube current, rotation time, and product of tube current and rotation time in mAs). A cardiac resynchronization therapy pacemaker (Insync 8040, Medtronic Inc., Tokyo) and 320 area detector CT scanner (Aquilion ONE, Toshiba medical systems, Otawara, Japan) with volume scan were used. The pacemaker was put in DDD mode. The PERs were interpreted using both the programmer's wave forms and error messages. The exposure was repeated 5 times per CT setting. The pacemaker was placed on the anterior wall and upper side of a chest phantom. Each CT scan was performed using the following parameters: tube voltage of 80, 100, 120, and 135 kV; tube current of 50-550 mA; and rotation time of 0.35-1.5 s. PERs were observed at 100, 120, and 135 kV, and more PERs were observed as the tube voltage increased. The PER tube current decreased as the rotation time was increased. In contrast, the PER tube current and rotation time product (mAs) increased as the rotation time was increased. More specifically, the radiation dose rate was the affected factor of the PERs. To avoid PER of pacemakers, CT scan parameters with lower radiation dose rates (low rather than high tube current and rotational time) is recommended. In conclusion, our results will help with CT scans of patients who have implantable cardiac devices (included pacemakers and cardioverter defibrillators).