Stress and reversible myocardial perfusion deficit measured by CT-MPI using a visual semiquantitative approach and a visually guided software-based approach show strong similarity with SPECT-MPI, suggesting that CT-MPI-based assessment of myocardial perfusion defects may be of clinical and prognostic value.
Cardiac 18 F-FDG PET has been used in clinics to assess myocardial glucose metabolism. Its ability for imaging myocardial glucose transport, however, has rarely been exploited in clinics. Using the dynamic FDG-PET scans of ten patients with coronary artery disease, we investigate in this paper appropriate dynamic scan and kinetic modeling protocols for efficient quantification of myocardial glucose transport. Three kinetic models and the effect of scan duration were evaluated by using statistical fit quality, assessing the impact on kinetic quantification, and analyzing the practical identifiability. The results show that the kinetic model selection depends on the scan duration. The reversible two-tissue model was needed for a one-hour dynamic scan. The irreversible two-tissue model was optimal for a scan duration of around 10-15 minutes. If the scan duration was shortened to 2-3 minutes, a one-tissue model was the most appropriate. For global quantification of myocardial glucose transport, we demonstrated that an early dynamic scan with a duration of 10-15 minutes and irreversible kinetic modeling was comparable to the full one-hour scan with reversible kinetic modeling. Myocardial glucose transport quantification provides an additional physiological parameter on top of the existing assessment of glucose metabolism and has the potential to enable single tracer multiparametric imaging in the myocardium.
Background During MitraClip implantation sub‐valvular correction of trajectory and/or alignment may increase adverse clip or leaflet events. With systematic adjunctive use of fluoroscopy (“Parallax technique”), we aimed to assess parameters that minimize the need for corrective measures and help increase procedural efficiency. Methods We retrospectively analyzed 30 patients without (Fl‐) and 39 patients utilizing adjunctive fluoroscopy (Fl+) during MitraClip implantation. After establishing trajectory and supra‐valvular alignment, the Parallax technique was utilized. Trajectory and alignment are maintained during advancement. Results All patients had 3 or 4+ MR. There were no differences in baseline demographics. The average number of clips (Fl‐ vs Fl+) was 1.72 ± 0.8 vs 1.59 ± 0.5, p = .57. For the first clip, the need for sub‐valvular alignment (80% vs. 36%, p = .0001), eversion with retraction back to left atrium (23% vs. 10%, p = .001) and the number of grasps (2.3 ± 1.2 vs 1.4 ± 0.9) was reduced. The time from transseptal puncture to first clip deployment (71 ± 21 vs 44 ± 16 min, p = .01) was reduced. Procedural success was achieved in all but one patient in the Fl‐ group (p = ns). There were no differences noted for in‐hospital or 30‐day outcomes. Conclusions Systematic use of a simple and easy to implement “Parallax technique” was associated with reduced need for sub‐valvular manipulation and was associated with improved procedural times. Further larger scale studies are needed to assess the applicability of the technique.
18 F-fluorodeoxyglucose (FDG) is a radiotracer widely used in positron emission tomography (PET) for metabolic imaging. PET with a perfusion-specific radiotracer (e.g. 82 Rb-chloride) has been used for quantification of myocardial blood flow (MBF) and flow reserve in clinics. However, the clinical accessibility of existing perfusion tracers remains limited. In this paper, we explore the potential of 18 F-FDG for myocardial perfusion imaging by comparing the myocardial FDG delivery rate K 1 with MBF as determined by dynamic 82 Rb PET in fourteen human subjects with ischemic heart disease (IHD) or non-IHD. Different scan protocols with appropriate kinetic models were compared for myocardial FDG K 1 quantification. Statistical associations between myocardial FDG K 1 and MBF were evaluated using both bivariate correlation analysis and multivariate regression analysis with potential confounding factors taken into account. Myocardial FDG K 1 and MBF were further evaluated for differentiating IHD from non-IHD using a numeric observer signal-to-noise ratio (SNR) and the receiver operating characteristic (ROC) analysis. The bivariate analysis shows that FDG K 1 is closely associated with MBF, demonstrating a high linear correlation in the IHD group. The association remains significant after adjusting for body mass index in the multivariate linear regression. Being lower in IHD than in non-IHD patients, both MBF and FDG K 1 can classify IHD from non-IHD with the area under the ROC curve equal to 0.85 or higher. It is also found that FDG K 1 had a lower detection performance than MBF according to the numeric observer SNR and ROC analysis. The results from this study show that dynamic cardiac FDG-PET with tracer kinetic modeling has the potential to provide a surrogate for MBF in addition to its conventional use for metabolic imaging. As compared to MBF, the use of FDG K 1 comes with a compromised performance, which may warrant further development for improved myocardial FDG flow quantification.
A 65-year-old male with a history of coronary artery disease and ankylosing spondylitis presented with focal ECG changes and elevated cardiac biomarkers suggestive of an acute lateral ST-elevation myocardial infarction. Emergent coronary angiography surprisingly showed non-obstructive coronary artery disease. Further workup including a cardiac MRI, viral serologies, and an endomyocardial biopsy was consistent with focal Coxsackie viral myocarditis. The patient subsequently developed recurrent, pulseless ventricular tachycardia requiring multiple rounds of ACLS, and his left ventricular ejection fraction acutely dropped from 55% to 20%. An emergent intra-aortic balloon pump was placed, and an intravenous lidocaine infusion and high-dose corticosteroids were started for the patient's electrical storm and myocarditis, respectively. The patient was eventually discharged in stable condition with an implantable cardiac defibrillator. No further episodes of ventricular tachycardia were noted at six-month follow-up. In patients with acute ECG changes, elevated cardiac biomarkers, and no evidence of obstructive coronary artery disease, myocarditis should be considered as a leading diagnosis given the potentially life-threatening sequelae as seen in our patient.
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