Toshifumi Mukunoki

Transluminal attenuation-gradient coronary CT angiography on a 320-MDCT volume scanner: Effect of scan timing, coronary artery stenosis, and cardiac output using a contrast medium flow phantom

PURPOSEnTransluminal-attenuation-gradient (TAG) may reflect patient characteristics and physiological parameters. Furthermore, TAG may be affected by factors such as the CT scanner speed, scanning method, scan timing after contrast-medium (CM) injection, and the injection methods. The purpose of our study was to investigate quantitative TAG at different scan timing points after CM injection for coronary CT angiography.nnnMATERIALS AND METHODSnUsing a CM flow phantom and two types of connecting tube mimicking 0% and 70% coronary artery stenosis, we performed 320-detector volume scanning. The heart rate was set at 60bpm and cardiac-output (CO) at 2.0 and 4.0xa0l/min, respectively. The acquisition time repeated at 0.5-s intervals for 40 and 25s at a CO of 2.0- and 4.0xa0l/min. We measured the CT number on the same slice level, calculated the time-density-curve (TDC) and the TAG at each time point.nnnRESULTSnAt COs of 2.0 and 4.0xa0l/min at 0% stenosis, TAG exhibited smaller variations (-3.02 to +0.55HU/cm at 2.0xa0l/min, -2.63 to +0.43HU/cm at 4.0xa0l/min) than at 70% stenosis at each time point along the TDC. Compared with a CO at 2.0xa0l/min with 70% stenosis, the TAG curve for a CO at 4.0xa0l/min gradually changed with time (-6.64 to +1.18HU/cm at 2.0xa0l/min vs. -3.46 to +2.75HU/cm at 4.0xa0l/min).nnnCONCLUSIONnThe TAG value was affected by scan timing after CM injection and by CO although the size of the connecting tube with and without stenosis was identical.

Evaluation of Collateral Source Characteristics With 3‐Dimensional Analysis Using Micro–X‐Ray Computed Tomography

Background Collateral arteries provide an alternative blood supply and protect tissues from ischemic damage in patients with peripheral artery disease. However, the mechanism of collateral artery development is difficult to validate. Methods and Results Collateral arteries were visualized using micro–x‐ray computed tomography. Developmental characteristics were assessed using confocal microscopy. We conducted a single‐center, retrospective, observational study and assessed the dilatation of collateral arteries on ischemic sides. We quantified the vascular volume in both ischemic and nonischemic legs. A prominent increase in vascular volume was observed in the ischemic leg using a murine hind‐limb ischemia model. We also performed qualitative assessment and confirmed that the inferior gluteal artery functioned as a major collateral source. Serial analysis of murine hind‐limb vessel development revealed that the inferior gluteal artery was a remnant of the ischial artery, which emerged as a representative vessel on the dorsal side during hind‐limb organogenesis. We retrospectively analyzed consecutive patients who were admitted for the diagnosis or treatment of peripheral artery disease. The diameter of the inferior gluteal artery on the ischemic side showed significant dilatation compared with that on the nonischemic side. Conclusions Our findings indicate that an embryonic remnant artery can become a collateral source under ischemic conditions. Flow enhancement in the inferior gluteal artery might become a novel therapeutic approach for patients with peripheral artery disease.

Unprotected left main intervention for surgery-ineligible patients with coronary artery disease—Usefulness of micro-CT images for stent

BACKGROUNDnPercutaneous coronary intervention (PCI) for unprotected left main truncus (LMT) lesions is controversial. Inoperable status with advanced age, renal dysfunction, frailty, or patient request may require an unprotected left main PCI. PCI for LMT is not recommended in the typical clinical situation; however, when it is the only feasible option, the performance is not bad. We demonstrated the result of a cobalt-chromium everolimus-eluting stent (CoCr-EES) in the LMT stenting and serial changes via micro-computed tomography (μCT). μCT is an established imaging technique used for high-resolution, non-destructive assessment of vascular samples. The technique has drawn increasing interest for investigations of atherosclerotic arteries in both humans and animal models. There are no reports regarding the linkage between clinical results and μCT images.nnnMETHODS AND RESULTSnBetween January 2009 and December 2014, we recruited 118 consecutive, unprotected LMT stenting cases in our institution. We examined the clinical outcomes and angiographic results with a CoCr-EES compared with a first-generation drug-eluting stent. The primary endpoint of this registry was the rate of one-year major adverse cardiac events (MACE). The one-year MACE rate was 2.54%; this did not include the CoCr-EES. We established LMT bifurcation models (mini-crush and culotte) using a CoCr-EES and obtained μCT images of the CoCr-EES. The images showed no deformation or strut apposition.nnnCONCLUSIONnCoCr-EES performed well in LMT in our institution and according to μCT. μCT images may be useful for anatomical simulation in stent deployment.

Visualization of Cracks in Compacted Clayey Soil Due to Using X-ray CT

The objective of this paper is to investigate the property change of compacted clayey soils for cover in the landfill subjected to moisture fluctuations and local deformation. Authors have tried to evaluate the crack behavior of compacted clayey soils due to punching loading without confining pressure. Based on the results of this study, mixing the rubber chips in the soil material was proposed as a new cover soil material. As consecutive study, conventional compacted clayey soils and compacted clayey soil with rubber chips were used for the following tests: the punching test and bending test with air compressing. At each level, the compacted clayey specimen is scanned using the X-ray computed tomography (CT) scanner and then, the density change in the specimen was visualized and evaluated quantitatively.