Total-Body PET/CT Applications in Cardiovascular Diseases: A Perspective Document of the SNMMI Cardiovascular Council.

Digital PET/CT systems with a long axial field of view have become available and are emerging as the current state of the art. These new camera systems provide wider anatomic coverage, leading to major increases in system sensitivity. Preliminary results have demonstrated improvements in image quality and quantification, as well as substantial advantages in tracer kinetic modeling from dynamic imaging. These systems also potentially allow for low-dose examinations and major reductions in acquisition time. Thereby, they hold great promise to improve PET-based interrogation of cardiac physiology and biology. Additionally, the whole-body coverage enables simultaneous assessment of multiple organs and the large vascular structures of the body, opening new opportunities for imaging systemic mechanisms, disorders, or treatments and their interactions with the cardiovascular system as a whole. The aim of this perspective document is to debate the potential applications, challenges, opportunities, and remaining challenges of applying PET/CT with a long axial field of view to the field of cardiovascular disease.

Prognostic value of coronary computed tomography angiography compared to radionuclide myocardial perfusion imaging in patients With coronary stents.

Objectives: The aim of this study is to compare the prognostic value of coronary computed tomography angiography (CCTA) with single-photon emission computed tomography (SPECT) in predicting cardiovascular events in patients with stents. Design: Retrospective analysis. Setting: University Hospital, London, Ontario Canada. Participants: Between January 2007 and December 2018, 119 patients post-percutaneous coronary intervention (PCI) who were referred for hybrid imaging with CTA and 2-day rest/stress SPECT were enrolled. Primary and secondary outcome measures: Patients were followed for any major adverse cardiovascular event (MACE) including: All-cause mortality, Non-fatal myocardial infarction (MI), Unplanned revascularization, Cerebrovascular accident and hospitalization for arrhythmia or heart failure. We define hard cardiac events (HCE) as: cardiac death, non-fatal MI or unplanned revascularization. We used two cut-off values to define obstructive lesions with CCTA ≥50% and ≥70% in any coronary segment. SPECT scan defined as abnormal in the presence of >5% reversible myocardial perfusion defect. Results: During the follow-up period of 7.2 ± 3.4 years. 45/119 (37.8%) patients experienced 57 MACE: Ten deaths (2 cardiac deaths and 8 of non-cardiac deaths), 29 acute coronary syndrome including non-fatal MI (25 required revascularization), 7 hospitalizations for heart failure, 6 cerebrovascular accidents and 5 new atrial fibrillation. 31 HCEs were reported. Cox regression analysis showed that obstructive coronary stenosis (≥50% and ≥70%) and abnormal SPECT were associated of MACE (p = 0.037, 0.018 and 0.026), respectively. In contrast, HCEs were significantly associated with obstructive coronary stenosis of ≥50% and ≥70% with p = 0.004 and p = 0.007, respectively. In contrast, abnormal SPECT was a nonsignificant predictor of HCEs (p = 0.062). Conclusion: Obstructive coronary artery stenosis on CCTA can predict MACE and HCE. However, abnormal SPECT can only predict MACE but not HCE in patients post-PCI with a follow-up period of approximately 7 years.

Comparison of cardio-focal and chest reconstruction of technetium-99m pyrophosphate scintigraphy for diagnosis of transthyretin cardiac amyloidosis: a quality assurance study.

BACKGROUND: SPECT improves diagnostic specificity of Technetium-99m pyrophosphate (PYP) scintigraphy. Diagnostic performance of PYP data, reconstructed as either chest or cardio-focal SPECT is not known. METHODS: In this quality assurance study, blinded evaluation of PYP SPECT/CT data from 102 Caucasian patients (mean age 76 ± 11 years, 67% men) was performed by two readers. Reader 1 reviewed planar and PYP chest SPECT, while reader 2 reviewed planar and cardio-focal PYP SPECT. Demographic, clinical, and other testing data were obtained from the electronic medical records. RESULTS: A total of 41 patients (40%) were considered positive based on myocardial uptake on chest PYP SPECT. Of these, 98% of the patients had a Perugini score ≥ 2 on planar imaging. There was good agreement between the two readers for visual score ≥ 2 (k = .88, P < .001) and excellent agreement for myocardial uptake on tomographic imaging (98%, P < .001). Only one study was categorized as false negative by cardio-focal SPECT reconstruction. Non-diffuse myocardial uptake was identified in 22% of those with a positive PYP SPECT. CONCLUSION: When read by experienced readers, chest and cardio-focal reconstruction of PYP SPECT have comparable diagnostic performance. A substantial proportion of patients with a positive PYP SPECT have a non-diffuse distribution of PYP. Given the possibility of misclassification of non-diffuse myocardial uptake on cardio-focal reconstruction alone, chest reconstruction of PYP scintigraphy should be strongly considered.

Complementary role of computed tomography angiography with fixed perfusion defects on SPECT myocardial perfusion imaging.

PURPOSE: We present this case series exploring the complementary role of coronary computed tomography angiography (CCTA) to SPECT myocardial perfusion imaging (MPI) in the detection of myocardial necrosis. METHODS: A cardiac hybrid imaging database search identified 144 patients with a previous history of ST-segment elevation myocardial infarction treated with coronary revascularization. CCTA and MPI scans were evaluated to determine whether CCTA had an added value to MPI in detecting myocardial necrosis. RESULTS: Five patients with patent stents and/or bypass grafts and both fixed perfusion defects on MPI and sub-endocardial hypo-perfusion on CCTA were identified. The extent and location of the perfusion defects were closely correlated between the CCTA and SPECT MPI images. CONCLUSION: In this series, CCTA and SPECT MPI were found to play a complementary role in the assessment of fixed perfusion defect, with CCTA adding specificity to the diagnosis of myocardial necrosis.

Coronary artery calcium progression after coronary artery bypass grafting surgery.

OBJECTIVES: Accelerated atherosclerosis is a well-established phenomenon after coronary artery bypass grafting surgery (CABG). In this study, we analysed coronary artery calcium (CCS) progression after CABG. METHODS: We retrospectively measured the CCS Agatston score (AS), volume score (VS) and mass score (MS) of 39 patients before and after CABG. The annualised CCS change and annualised CCS percent change of each coronary artery, coronary artery segments proximal and distal to anastomosis were analysed. RESULTS: Mean age at the time of the surgery was 59.8±8.5 years. Follow-up period between the first and second CT scans was 6.7±2.8 (range, 1.1-12.8) years. Annualised CCS percent change (AS, VS and MS) of the coronary segments proximal-to-anastomosis did not differ from that of the non-grafted coronary arteries as follow: segments proximal-to-anastomosis: median (Q1-Q3) 12.8 (5.0-37.4), 13.7 (6.1-41.1) and 14.9 (5.4-53.7), left main coronary artery 12.6 (7.4-43.8), 22.0 (8.1-44.4) and 18.2 (7.3-57.4), non-grafted left circumflex artery: 13.5 (4.4-38.1), 10.5 (2.9-45.2) and 11.5 (7.1-47.9) and non-grafted right coronary artery: 31.4 (14.4-74.5), 25.2 (16.7-62.0) and 31.3 (23.8-85.6), respectively. Likewise, annualised percent change (AS, VS and MS) was similar between the native coronary arteries. Multivariate regression analysis showed that diabetes mellitus was the only predictor of annualised percent progression of the total CCS of >15% (HR, 8.12; 95% CI, 1.05 to 26.6; p=0.04). CONCLUSION: The CCS post-CABG did not follow an accelerated progression process. Among coronary artery disease risk factors, diabetes mellitus is the only predictor of annualised CCS percent progression of >15% post-CABG.

Hiatal hernia after robotic-assisted coronary artery bypass graft surgery.

BACKGROUND: The aim of the present study is to determine the incidence/progression of hiatal hernia (HH) after robotic-assisted coronary artery bypass grafting (RA-CABG) surgery. METHODS: We reviewed the pre- and post-operative computed tomography (CT) of 491 patients who underwent RA-CABG between 2000 and 2017. Post-operative CT was acquired prospectively in a research protocol. CT was reviewed to assess the presence and the size of HH. RESULTS: We found 444/491 (90.4%) had pre-operative CT, while 201/491 (40.9%) had post-operative CT. In total, 155/491 (31.6%) had both pre- and long-term post-operative CT with a mean follow-up of 6.2 (±3.5) years. HH was more prevalent on post-operative CT, 64/155 (41.3%) compared to pre-operative CT, 44/155 (28.4%), P<0.0001. The diameter of pre-existing HH 2.8 (±1.8) cm was significantly greater after surgery 3.9 (±2.5) cm, P<0.0001. As well the volume of the pre-existing HH 5.8 (4.4-9.2) mL (quartile) was significantly greater after surgery 14.1 (7.2-64.9) mL, P<0.0001. 20/155 (12.9%) had a newly developed HH after RA-CABG. A binary multivariate regression including HH risk factors showed that male gender is a predictor of developing a HH after RA-CABG with Hazard Ratio of 3.038, confidence interval (1.10-8.43), P=0.033. CONCLUSIONS: RA-CABG is associated with an increased risk of developing HH and increases the size of pre-existing HH.

Controversies Surrounding the BMD Reporting Standard for the Determination of 10-Year Absolute Fracture Risk: A Canadian Perspective.

The Canadian Association of Radiologists and Osteoporosis Canada currently endorse a fracture risk prediction tool called CAROC. It has been used in Canada since 2005 with an update in 2010. It is an integral part of bone mineral densitometry reporting across the country. New osteoporosis guidelines from Osteoporosis Canada (OC) are expected in the near future. There has been pressure on radiologists to report fracture risk using an alternative fracture risk prediction platform called FRAX. In addition, OC collaborated in the development of the Canadian FRAX model and has been copromoting both FRAX and CAROC, raising the prospect that new guidelines may seek to replace CAROC with FRAX for fracture risk determination. A number of concerns have been raised about FRAX, including: (1) FRAX has not released its algorithms to the public domain with the consequence that it is impossible to verify results for an individual patient; (2) FRAX has incorrectly claimed that it was developed by the World Health Organization (WHO) and has used this affiliation to promote itself until recently ordered by the WHO to desist; (3) FRAX requires collection of additional clinical information beyond that needed for CAROC, and this patient-reported medical data is prone to substantial error; and (4) despite claims to the contrary, there are no valid studies comparing FRAX to CAROC. We believe it is important that radiologists be aware of these issues in order to provide input into future Technical Standards for Bone Mineral Densitometry Reporting of the Canadian Association of Radiologists.

Internal Jugular Vein and Cerebral Venous Sinus Infective Thrombophlebitis Detected With 99mTc-HMPAO White Blood Cell Scintigraphy.

ABSTRACT: A 35-year-old man with a history of renal transplant, congenital cystinosis, and diabetes was admitted to the hospital with fever, bilateral parotid gland swelling, and acute renal failure. He had 99mTc-HMPAO-WBC (99mTc-hexamethylpropyleneamineoxime white blood cell) imaging for the evaluation of possible parotitis. There was intense radiopharmaceutical uptake along the right internal jugular vein extending to the right sigmoid and transverse and superior sagittal sinuses, suggestive of infective thrombophlebitis or Lemierre syndrome. This study illustrates the value of 99mTc-HMPAO-WBC imaging as a tool for evaluating thrombophlebitis, particularly in patients with renal failure in whom contrast-enhanced CT may not be possible.

Very high coronary artery calcium score with normal myocardial perfusion SPECT imaging is associated with a moderate incidence of severe coronary artery disease.

PURPOSE: Myocardial perfusion imaging (MPI) has limitations in the presence of balanced multivessel disease (MVD) and left main (LM) coronary artery disease, occasionally resulting in false-normal results despite the high cardiovascular risk associated with this condition. The purpose of this study was to assess the incidence of severe coronary artery disease (CAD) in the presence of a very high Agatston coronary artery calcium (CAC) score (>1,000) in stable symptomatic patients without known CAD but with normal MPI results. METHODS: A total of 2,659 prospectively acquired consecutive patients were referred for MPI and evaluation of CAC score by CT. Of this patient population, 8 % (222/2,659) had ischemia without myocardial infarction (MI) on MPIand 11 % (298/2,659) had abnormal MPI (MI and/or ischemia). On presentation 1 % of the patients (26/2,659) were symptomatic, had a CAC score >1,000 and normal MPI results. The definition of normal MPI was strict and included a normal hemodynamic response without ischemic ECG changes and normal imaging, particularly absence of transient ischemic dilation. All of these 26 patients with a CAC score >1,000 and normal MPI findings underwent cardiac catheterization. RESULTS: Of these 26 patients, 58 % (15/26) had severe disease (≥70 % stenosis) leading to revascularization. Of this group, 47 % (7/15) underwent percutaneous intervention, and 53 % (8/15) underwent coronary artery bypass grafting. All of these 15 patients had either MVD (14/15) or LM coronary artery disease (1/15), and represented 0.6 % (15/2,659) of all referred patients (95 % CI 0.3 - 0.9 %). The majority, 90 % (8/9), had severe CAD with typical chest pain. CONCLUSION: A very high CAC score (>1,000) with normal MPI in a small subset of symptomatically stable patients was associated with a moderate incidence of severe CAD (95 % CI 37 - 77 %). Larger studies and/or a meta-analysis of small studies are needed to more precisely estimate the incidence of CAD in this population. This study also supports the concept that a normal MPI result in patients with severe CAD may be due to balanced MVD.