Combining anatomical and biochemical markers in the detection and risk stratification of coronary artery disease

AIM

We aimed to test the hypothesis if combining coronary artery calcium score (Ca-score) as a quantitative anatomical marker of coronary atherosclerosis with high-sensitive cardiac troponin as a quantitative biochemical marker of myocardial injury provided incremental value in the detection of functional relevant CAD (fCAD) and risk stratification.

METHODS AND RESULTS

Consecutive patients undergoing myocardial perfusion SPECT (MPS) without prior CAD were enrolled. The diagnosis of fCAD was based on the presence of ischemia on MPS and coronary angiography- fCAD was centrally adjudicated in the diagnostic and prognostic domain. Diagnostic accuracy was evaluated using the area under receiver-operating characteristic curve. The composite of cardiovascular death and non-fatal acute myocardial infarction (AMI) within 730 days were the primary prognostic endpoints.Among 1715 patients eligible for the diagnostic analysis, 399 patients had fCAD. The combination of Ca-Score and hs-cTnT had good diagnostic accuracy for the diagnosis of fCAD, AUC 0.79 (95 % CI 0.77-0.81), but no incremental value compared to the Ca-score alone (AUC 0.79 (95%CI 0.77-0.81, p=0.965). Similar results were observed using hs-cTnI (AUC 0.80, 95%CI 0.77-0.82) instead of hs-cTnT.Among 1709 patients (99.7%) with available follow-up, 59 patients (3.5%) suffered the composite primary prognostic endpoint (nonfatal AMI n=34, CV death n=28).Both, Ca-score and hs-cTnT had independent prognostic value. Increased risk was restricted to patients with elevation in both markers.

CONCLUSION

The combination of the Ca-score with hs-cTnT increases the prognostic accuracy for future events defining fCAD, but does not provide incremental value versus the Ca-Score alone for the diagnosis of fCAD.

The clinical acceptability of short versus long duration acquisitions for head and neck cancer using long-axial field-of-view PET/CT: a retrospective evaluation

PURPOSE

To evaluate the utility of long duration (10 min) acquisitions compared to standard 4 min scans in the evaluation of head and neck cancer (HNC) using a long-axial field-of-view (LAFOV) system in 2-[18F]FDG PET/CT.

METHODS

HNC patients undergoing LAFOV PET/CT were included retrospectively according to a predefined sample size calculation. For each acquisition, FDG avid lymph nodes (LN) which were highly probable or equivocal for malignancy were identified by two board certified nuclear medicine physicians in consensus. The aim of this study was to establish the clinical acceptability of short-duration (4 min, C40%) acquisitions compared to full-count (10 min, C100%) in terms of the detection of LN metastases in HNC. Secondary endpoints were the positive predictive value for LN status (PPV) and comparison of SUVmax at C40% and C100%. Histology reports or confirmatory imaging were the reference standard.

RESULTS

A total of 1218 records were screened and target recruitment was met with n = 64 HNC patients undergoing LAFOV. Median age was 65 years (IQR: 59-73). At C40%, a total of 387 lesions were detected (highly probable LN n = 274 and equivocal n = 113. The total number of lesions detected at C100% acquisition was 439, of them 291 (66%) highly probable LN and 148 (34%) equivocal. Detection rate between the two acquisitions did not demonstrate any significant differences (Pearson's Chi-Square test, p = 0.792). Sensitivity, specificity, PPV, NPV and accuracy for C40% were 83%, 44%, 55%, 76% and 36%, whilst for C100% were 85%, 56%, 55%, 85% and 43%, respectively. The improved accuracy reached borderline significance (p = 0.057). At the ROC analysis, lower SUVmax was identified for C100% (3.5) compared to C40% (4.5).

CONCLUSION

In terms of LN detection, C40% acquisitions showed no significant difference compared to the C100% acquisitions. There was some improvement for lesions detection at C100%, with a small increment in accuracy reaching borderline significance, suggestive that the higher sensitivity afforded by LAFOV might translate to improved clinical performance in some patients.

Internal dosimetry study of [82Rb]Cl using a long axial field-of-view PET/CT

PURPOSE

Long axial field-of-view (LAFOV) positron emission tomography (PET) systems allow to image all major organs with one bed position, which is particularly useful for acquiring whole-body dynamic data using short-lived radioisotopes like 82Rb.

METHODS

We determined the absorbed dose in target organs of three subjects (29, 40, and 57 years old) using two different methods, i.e., MIRD and voxel dosimetry. The subjects were injected with 407.0 to 419.61 MBq of [82Rb]Cl and were scanned dynamically for 7 min with a LAFOV PET/CT scanner.

RESULTS

Using the MIRD formalism and voxel dosimetry, the absorbed dose ranged from 1.84 to 2.78 μGy/MBq (1.57 to 3.92 μGy/MBq for voxel dosimetry) for the heart wall, 2.76 to 5.73 μGy/MBq (3.22 to 5.37 μGy/MBq for voxel dosimetry) for the kidneys, and 0.94 to 1.88 μGy/MBq (0.98 to 1.92 μGy/MBq for voxel dosimetry) for the lungs. The total body effective dose lied between 0.50 and 0.76 μSv/MBq.

CONCLUSION

Our study suggests that the radiation dose associated with [82Rb]Cl PET/CT can be assessed by means of dynamic LAFOV PET and that it is lower compared to literature values.

FDG imaging with long-axial field-of-view PET/CT in patients with high blood glucose-a matched pair analysis

PURPOSE

High blood glucose (hBG) in patients undergoing [18F]FDG PET/CT scans often results in rescheduling the examination, which may lead to clinical delay for the patient and decrease productivity for the department. The aim of this study was to evaluate whether long-axial field-of-view (LAFOV) PET/CT can minimize the effect of altered bio-distribution in hBG patients and is able to provide diagnostic image quality in hBG situations.

MATERIALS AND METHODS

Oncologic patients with elevated blood glucose (≥ 8.0 mmol/l) and normal blood glucose (< 8.0 mmol/l, nBG) levels were matched for tumor entity, gender, age, and BMI. hBG patients were further subdivided into two groups (BG 8-11 mmol/l and BG > 11 mmol/l). Tracer uptake in the liver, muscle, and tumor was evaluated. Furthermore, image quality was compared between long acquisitions (ultra-high sensitivity mode, 360 s) on a LAFOV PET/CT and routine acquisitions equivalent to a short-axial field-of-view scanner (simulated (sSAFOV), obtained with high sensitivity mode, 120 s). Tumor-to-background ratio (TBR) and contrast-to-noise ratio (CNR) were used as the main image quality criteria.

RESULTS

Thirty-one hBG patients met the inclusion criteria and were matched with 31 nBG patients. Overall, liver uptake was significantly higher in hBG patients (SUVmean, 3.07 ± 0.41 vs. 2.37 ± 0.33; p = 0.03), and brain uptake was significantly lower (SUVmax, 7.58 ± 0.74 vs. 13.38 ± 3.94; p < 0.001), whereas muscle (shoulder/gluteal) uptake showed no statistically significant difference. Tumor uptake was lower in hBG patients, resulting in a significantly lower TBR in the hBG cohort (3.48 ± 0.74 vs. 5.29 ± 1.48, p < 0.001). CNR was higher in nBG compared to hBG patients (12.17 ± 4.86 vs. 23.31 ± 12.22, p < 0.001). However, subgroup analysis of nBG 8-11 mmol/l on sSAFOV PET/CT compared to hBG (> 11 mmol/l) patients examined with LAFOV PET/CT showed no statistical significant difference in CNR (19.84 ± 8.40 vs. 17.79 ± 9.3, p = 0.08).

CONCLUSION

While elevated blood glucose (> 11 mmol) negatively affected TBR and CNR in our cohort, the images from a LAFOV PET-scanner had comparable CNR to PET-images acquired from nBG patients using sSAFOV PET/CT. Therefore, we argue that oncologic patients with increased blood sugar levels might be imaged safely with LAFOV PET/CT when rescheduling is not feasible.

Current and Evolving Multimodality Cardiac Imaging in Managing Transthyretin Amyloid Cardiomyopathy

Amyloid transthyretin (ATTR) amyloidosis is a protein-misfolding disease characterized by fibril accumulation in the extracellular space that can result in local tissue disruption and organ dysfunction. Cardiac involvement drives morbidity and mortality, and the heart is the major organ affected by ATTR amyloidosis. Multimodality cardiac imaging (ie, echocardiography, scintigraphy, and cardiac magnetic resonance) allows accurate diagnosis of ATTR cardiomyopathy (ATTR-CM), and this is of particular importance because ATTR-targeting therapies have become available and probably exert their greatest benefit at earlier disease stages. Apart from establishing the diagnosis, multimodality cardiac imaging may help to better understand pathogenesis, predict prognosis, and monitor treatment response. The aim of this review is to give an update on contemporary and evolving cardiac imaging methods and their role in diagnosing and managing ATTR-CM. Further, an outlook is presented on how artificial intelligence in cardiac imaging may improve future clinical decision making and patient management in the setting of ATTR-CM.

Long-axial field-of-view PET/CT for the assessment of inflammation in calcified coronary artery plaques with [68 Ga]Ga-DOTA-TOC

PURPOSE

Inflamed, prone-to-rupture coronary plaques are an important cause of myocardial infarction and their early identification is crucial. Atherosclerotic plaques are characterized by overexpression of the type-2 somatostatin receptor (SST2) in activated macrophages. SST2 ligand imaging (e.g. with [68 Ga]Ga-DOTA-TOC) has shown promise in detecting and quantifying the inflammatory activity within atherosclerotic plaques. However, the sensitivity of standard axial field of view (SAFOV) PET scanners may be suboptimal for imaging coronary arteries. Long-axial field of view (LAFOV) PET/CT scanners may help overcome this limitation. We aim to assess the ability of [68 Ga]Ga-DOTA-TOC LAFOV-PET/CT in detecting calcified, SST2 overexpressing coronary artery plaques.

METHODS

In this retrospective study, 108 oncological patients underwent [68 Ga]Ga-DOTA-TOC PET/CT on a LAFOV system. [68 Ga]Ga-DOTA-TOC uptake and calcifications in the coronary arteries were evaluated visually and semi-quantitatively. Data on patients' cardiac risk factors and coronary artery calcium score were also collected. Patients were followed up for 21.5 ± 3.4 months.

RESULTS

A total of 66 patients (61.1%) presented with calcified coronary artery plaques. Of these, 32 patients had increased [68 Ga]Ga-DOTA-TOC uptake in at least one coronary vessel (TBR: 1.65 ± 0.53). Patients with single-vessel calcifications showed statistically significantly lower uptake (SUVmax 1.10 ± 0.28) compared to patients with two- (SUVmax 1.31 ± 0.29, p < 0.01) or three-vessel calcifications (SUVmax 1.24 ± 0.33, p < 0.01). There was a correlation between coronary artery calcium score (CACS) and [68 Ga]Ga-DOTA-TOC uptake, especially in the LAD (p = 0.02). Stroke and all-cause death occurred more frequently in patients with increased [68 Ga]Ga-DOTA-TOC uptake (15.63% vs. 0%; p:0.001 and 21.88% vs. 6.58%; p: 0.04, respectively) during the follow-up period.

CONCLUSION

[68 Ga]Ga-DOTA-TOC as a marker for the macrophage activity can reveal unknown cases of inflamed calcified coronary artery plaques using a LAFOV PET system. [68 Ga]Ga-DOTA-TOC uptake increased with the degree of calcification and correlated with higher risk of stroke and all-cause death. [68 Ga]Ga-DOTA-TOC LAFOV PET/CT may be useful to assess patients' cardiovascular risk.

What Role Does PET/MRI Play in Musculoskeletal Disorders?

Musculoskeletal disorders of nononcological origin are one of the most frequent reasons for consultation. Patients suffering from musculoskeletal disorders also consult more than once for the same reason. This results in multiple clinical follow-ups after several radiological and serum examinations, the main ones including X-rays targeting the painful anatomical region and inflammatory serum parameters. As part of their work up, patients suffering from musculoskeletal disorders often require multisequence, multi-parameter MRI. PET/MRI is a promising imaging modality for their diagnosis, with the added advantage of being able to be performed in a single visit. PET/MRI is particularly useful for diagnosing osteomyelitis, spondylodiscitis, arthritis, many pediatric pathologies, and a wide range of other musculoskeletal pathologies. PET/MRI is already used to diagnose malignant bone tumors such as osteosarcoma. However, current knowledge of the indications for PET/MRI in nononcological musculoskeletal disorders is based on studies involving only a few patients. This review focuses on the usefulness of PET/MRI for diagnosing nononcological musculoskeletal disorders.

Coronary artery calcium score and pre-test probabilities as gatekeepers to predict and rule out perfusion defects in positron emission tomography

BACKGROUND

Little is known about the gatekeeper performance of coronary artery calcium score (CACS) before myocardial perfusion positron emission tomography (PET), compared with updated pre-test probabilities from American and European guidelines (pre-test-AHA/ACC, pre-test-ESC).

METHODS

We enrolled participants without known coronary artery disease undergoing CACS and Rubidium-82 PET. Abnormal perfusion was defined as summed stress score ≥ 4. Using Bayes' formula, pre-test probabilities and CACS were combined into post-test probabilities.

RESULTS

We included 2050 participants (54% male, mean age 64.6 years) with median CACS 62 (IQR 0-380), pre-test-ESC 17% (11-26), pre-test-AHA/ACC 27% (16-44), and abnormal perfusion in 437 participants (21%). To predict abnormal perfusion, area under the curve of CACS was 0.81, pre-test-AHA/ACC 0.68, pre-test-ESC 0.69, post-test-AHA/ACC 0.80, and post-test-ESC 0.81 (P < 0.001 for CACS vs. each pre-test, and each post-test vs. pre-test). CACS = 0 had 97% negative predictive value (NPV), pre-test-AHA/ACC ≤ 5% 100%, pre-test-ESC ≤ 5% 98%, post-test-AHA/ACC ≤ 5% 98%, and post-test-ESC ≤ 5% 96%. Among participants, 26% had CACS = 0, 2% pre-test-AHA/ACC ≤ 5%, 7% pre-test-ESC ≤ 5%, 23% post-test-AHA/ACC ≤ 5%, and 33% post-test-ESC ≤ 5% (all P < 0.001).

CONCLUSIONS

CACS and post-test probabilities are excellent predictors of abnormal perfusion and can rule it out with very high NPV in a substantial proportion of participants. CACS and post-test probabilities may be used as gatekeepers before advanced imaging. Coronary artery calcium score (CACS) predicted abnormal perfusion (SSS ≥ 4) in myocardial positron emission tomography (PET) better than pre-test probabilities of coronary artery disease (CAD), while pre-test-AHA/ACC and pre-test-ESC performed similarly (left). Using Bayes' formula, pre-test-AHA/ACC or pre-test-ESC were combined with CACS into post-test probabilities (middle). This calculation reclassified a substantial proportion of participants to low probability of CAD (0-5%), not needing further imaging, as shown for AHA/ACC probabilities (2% with pre-test-AHA/ACC to 23% with post-test-AHA/ACC, P < 0.001, right). Very few participants with abnormal perfusion were classified under pre-test or post-test probabilities 0-5%, or under CACS 0. AUC: area under the curve. Pre-test-AHA/ACC: Pre-test probability of the American Heart Association/American College of Cardiology. Post-test-AHA/ACC: Post-test probability combining pre-test-AHA/ACC and CACS. Pre-test-ESC: Pre-test probability of the European Society of Cardiology. SSS: Summed stress score.

Routine 4D Cardiac CT to Identify Concomitant Transthyretin Amyloid Cardiomyopathy in Older Adults with Severe Aortic Stenosis

Background Transthyretin amyloid cardiomyopathy (ATTR-CM) often coexists with severe aortic stenosis (AS). Although strain analysis from cardiac MRI and echocardiography was demonstrated to predict coexisting ATTR-CM, comparable data from four-dimensional (4D) cardiac CT are lacking despite wide availability. Purpose To evaluate the diagnostic performance of 4D cardiac CT-derived parameters in identifying ATTR-CM in older adults considered for transcatheter aortic valve implantation (TAVI). Materials and Methods This prospective single-center screening study for ATTR-CM included consecutive patients with severe AS considered for TAVI who underwent 4D cardiac CT between August 2019 and August 2021 approximately 1 day before technetium 99m (99mTc) 3,3-diphosphono-1,2-propanodicarboxylic-acid (DPD) scintigraphy. The diagnostic performance of CT-based left ventricular (LV), right ventricular, and left atrial dimensions, ejection fraction (EF), and myocardial strain were evaluated against 99mTc-DPD scintigraphy as the reference standard to identify ATTR-CM. Predictors and an unweighted cardiac CT score were validated with internal bootstrapping. The assignment of variables to the score was based on cutoff values achieving the highest Youden index J. Results Among 263 participants (mean age, 83 years ± 4.6 [SD]; 149 male and 114 female participants), 99mTc-DPD scintigraphy (Perugini grade 2 or 3) confirmed coexisting ATTR-CM in 27 (10.3%). CT-derived LV mass index, LV and LA global longitudinal strain (GLS), and relative apical longitudinal strain each predicted the presence of ATTR-CM with an area under the curve (AUC) of at least 0.70. Implementing these parameters with cutoff values of 81 g/m2 or higher, -14.9% or higher, less than 11.5%, and 1.7 or higher in the CT score, respectively, yielded high diagnostic performance (AUC = 0.89; 95% CI: 0.81, 0.94; P < .001) robust to internal bootstrapping validation (AUC = 0.88; 95% CI: 0.82, 0.94). If two criteria were fulfilled, the sensitivity and specificity in the detection of ATTR-CM were 96.3% (95% CI: 81.0, 99.9) and 58.9% (95% CI: 52.3, 65.2), respectively. Conclusion When compared against 99mTc-DPD scintigraphy as the reference standard, routine 4D cardiac CT in older adults considered for TAVI provided high diagnostic performance in the detection of concomitant ATTR-CM by assessing LV and left atrial GLS, relative apical longitudinal strain, and LV mass index. ClinicalTrials.gov registration no.: NCT04061213 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Tavakoli and Onder in this issue.

Cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) imaging in the diagnosis and follow-up of patients with acute myocarditis and chronic inflammatory cardiomyopathy : A review paper with practical recommendations on behalf of the European Society of Cardiovascular Radiology (ESCR)

Advanced cardiac imaging techniques such as cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) are widely used in clinical practice in patients with acute myocarditis and chronic inflammatory cardiomyopathies (I-CMP). We aimed to provide a review article with practical recommendations from the European Society of Cardiovascular Radiology (ESCR), in order to guide physicians in the use and interpretation of CMR and PET in clinical practice both for acute myocarditis and follow-up in chronic forms of I-CMP.

New thresholds in semi-quantitative [18F]FDG PET/CT are needed to assess large vessel vasculitis with long-axial field-of-view scanners

AIM

[18F]FDG PET/CT proved accurate in the diagnostic work-up of large vessel vasculitis (LVV). While a visual interpretation is currently considered adequate, several attempts have been made to integrate it with a semiquantitative evaluation. In this regard, there is the need to validate current or new thresholds for the semiquantitative parameters on long-axial field of view (LAFOV) scanners.

METHODS

We retrospectively evaluated 100 patients (50 with LVV and 50 controls) who underwent [18F]FDG LAFOV PET/CT. Semiquantitative parameters (SUVmax and SUVmean) were calculated for large vessels in 3 districts (supra-aortic [SA], thoracic aorta [TA], and infra-aortic [IA]). Values were also normalized to liver activity (SUVmax/L-SUVmax, and SUVmax/L-SUVmean).

RESULTS

Of the 50 patients diagnosed with LVV, SA vessels were affected in 38 (76%), TA in 42 (84%) and IA vessels in 26 (52%). To-liver normalized values had higher diagnostic accuracy than non-normalized values (AUC always ≥ 0.90 vs. 0.74-0.89). For the SA vessels, best thresholds were 0.66 for SUVmax/L-SUVmax and 0.88 for SUVmax/L-SUVmean; for the TA, 1.0 for SUVmax/L-SUVmax and 1.30 for SUVmax/L-SUVmean; finally, for IA vessels, the best threshold was 0.83 for SUVmax/L-SUVmax and 1.11 for SUVmax/L-SUVmean.

CONCLUSION

LAFOV [18F]FDG-PET/CT is accurate in the diagnostic workup of LVV, but different threshold in semi-quantitative parameters than reported in literature for standard scanners should be considered.

The power of zero calcium in 82-Rubidium PET irrespective of sex and age

BACKGROUND

Despite clinical suspicion, many non-invasive tests for coronary artery disease (CAD) are normal. Coronary artery calcification score (CACS) is a well-validated method to detect and risk stratify CAD. Patients with zero calcium score (ZCS) rarely have abnormal tests. Therefore, aims were to evaluate CACS as a gatekeeper to further functional downstream testing for CAD and estimate potential radiation and cost savings.

METHODS

Consecutive patients with suspected CAD referred for PET were included (n = 2640). Prevalence and test characteristics of ZCS were calculated in different groups. Summed stress score ≥ 4 was considered abnormal and summed difference score ≥ 7 equivalent to ≥ 10% ischemia. To estimate potential radiation/cost reduction, PET scans were hypothetically omitted in ZCS patients.

RESULTS

Mean age was 65 ± 11 years, 46% were female. 21% scans were abnormal and 26% of patients had ZCS. CACS was higher in abnormal PET (median 561 vs 27, P < 0.001). Abnormal PET was significantly less frequent in ZCS patients (2.6% vs 27.6%, P < 0.001). Sensitivity/negative predictive value (NPV) of ZCS to detect/exclude abnormal PET and ≥ 10% ischemia were 96.8% (95%-CI 95.0%-97.9%)/97.4% (95.9%-98.3%) and 98.9% (96.7%-99.6%)/99.6% (98.7%-99.9%), respectively. Radiation and cost reduction were estimated to be 23% and 22%, respectively.

CONCLUSIONS

ZCS is frequent, and most often consistent with normal PET scans. ZCS offers an excellent NPV to exclude an abnormal PET and ≥ 10% ischemia across different gender and age groups. CACS is a suitable gatekeeper before advanced cardiac imaging, and potential radiation/cost savings are substantial. However, further studies including safety endpoints are needed.

Low-dose coronary artery calcium scoring compared to the standard protocol

BACKGROUND

We aimed to compare coronary artery calcium scoring (CACS) with computed tomography (CT) with 80 and 120 kVp in a large patient population and to establish whether there is a difference in risk classification between the two scores.

METHODS

Patients with suspected CAD undergoing MPS were included. All underwent standard CACS assessment with 120-kVp tube voltage and with 80 kVp. Two datasets (low-dose and standard) were generated and compared. Risk classes (0 to 25, 25 to 50, 50 to 75, 75 to 90, and > 90%) were recorded.

RESULTS

1511 patients were included (793 males, age 69 ± 9.1 years). There was a very good correlation between scores calculated with 120 and 80 kVp (R = 0.94, R2 = 0.88, P < .001), with Bland-Altman limits of agreement of - 563.5 to 871.9 and a bias of - 154.2. The proportion of patients assigned to the < 25% percentile class (P = .03) and with CACS = 0 differed between the two protocols (n = 264 vs 437, P < .001).

CONCLUSION

In a large patient population, despite a good correlation between CACS calculated with standard and low-dose CT, there is a systematic underestimation of CACS with the low-dose protocol. This may have an impact especially on the prognostic value of the calcium score, and the established "power of zero" may no longer be warranted if CACS is assessed with low-dose CT.

The prognostic value of CZT SPECT myocardial blood flow (MBF) quantification in patients with ischemia and no obstructive coronary artery disease (INOCA): a pilot study

BACKGROUND

Despite the demonstrated adverse outcome, it is difficult to early identify the risks for patients with ischemia and no obstructive coronary artery disease (INOCA). We aimed to explore the prognostic potential of CZT SPECT in INOCA patients.

METHODS

The study population consisted of a retrospective cohort of 118 INOCA patients, all of whom underwent CZT SPECT imaging and invasive coronary angiography (ICA). Dynamic data were reconstructed, and MBF was quantified using net retention model. Major adverse cardiovascular events (MACEs) were defined as cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, heart failure, late coronary revascularization, or hospitalization for unstable angina.

RESULTS

During a median follow-up of 15 months (interquartile range (IQR) 11-20), 19 (16.1%) MACEs occurred; both stress myocardial blood flow (sMBF) ([Formula: see text]) and coronary flow reserve (CFR) ([Formula: see text]) were significantly lower in the MACE group. Optimal thresholds of sMBF<3.16 and CFR<2.52 were extracted from the ROC curves, and both impaired sMBF (HR: 15.08; 95% CI 2.95-77.07; [Formula: see text]) and CFR (HR: 6.51; 95% CI 1.43-29.65; [Formula: see text]) were identified as prognostic factors for MACEs. Only sMBF<3.16 (HR: 11.20; 95% CI 2.04-61.41; [Formula: see text]) remained a robust predictor when sMBF and CFR were integrated considered. Compared with CFR, sMBF provides better prognostic model discrimination and reclassification ability (C-index improvement = 0.06, [Formula: see text]; net reclassification improvement (NRI) = 0.19; integrated discrimination improvement (IDI) = 0.10).

CONCLUSION

The preliminary results demonstrated that quantitative analysis on CZT SPECT provides prognostic value for INOCA patients, which may allow the stratification for early prevention and intervention.

State-of-the-art CT and MR imaging and assessment of atherosclerotic carotid artery disease: the reporting-a consensus document by the European Society of Cardiovascular Radiology (ESCR)

The European Society of Cardiovascular Radiology (ESCR) is the European specialist society of cardiac and vascular imaging. This society's highest priority is the continuous improvement, development, and standardization of education, training, and best medical practice, based on experience and evidence. The present intra-society consensus is based on the existing scientific evidence and on the individual experience of the members of the ESCR writing group on carotid diseases, the members of the ESCR guidelines committee, and the members of the executive committee of the ESCR. The recommendations published herein reflect the evidence-based society opinion of ESCR. The purpose of this second document is to discuss suggestions for standardized reporting based on the accompanying consensus document part I. KEY POINTS: • CT and MR imaging-based evaluation of carotid artery disease provides essential information for risk stratification and prediction of stroke. • The information in the report must cover vessel morphology, description of stenosis, and plaque imaging features. • A structured approach to reporting ensures that all essential information is delivered in a standardized and consistent way to the referring clinician.

State-of-the-art CT and MR imaging and assessment of atherosclerotic carotid artery disease: standardization of scanning protocols and measurements-a consensus document by the European Society of Cardiovascular Radiology (ESCR)

The European Society of Cardiovascular Radiology (ESCR) is the European specialist society of cardiac and vascular imaging. This society's highest priority is the continuous improvement, development, and standardization of education, training, and best medical practice, based on experience and evidence. The present intra-society consensus is based on the existing scientific evidence and on the individual experience of the members of the ESCR writing group on carotid diseases, the members of the ESCR guidelines committee, and the members of the executive committee of the ESCR. The recommendations published herein reflect the evidence-based society opinion of ESCR. We have produced a twin-papers consensus, indicated through the documents as respectively "Part I" and "Part II." The first document (Part I) begins with a discussion of features, role, indications, and evidence for CT and MR imaging-based diagnosis of carotid artery disease for risk stratification and prediction of stroke (Section I). It then provides an extensive overview and insight into imaging-derived biomarkers and their potential use in risk stratification (Section II). Finally, detailed recommendations about optimized imaging technique and imaging strategies are summarized (Section III). The second part of this consensus paper (Part II) is focused on structured reporting of carotid imaging studies with CT/MR. KEY POINTS: • CT and MR imaging-based evaluation of carotid artery disease provides essential information for risk stratification and prediction of stroke. • Imaging-derived biomarkers and their potential use in risk stratification are evolving; their correct interpretation and use in clinical practice must be well-understood. • A correct imaging strategy and scan protocol will produce the best possible results for disease evaluation.

Artificial Intelligence in Breast Cancer: A Systematic Review on PET Imaging Clinical Applications

BACKGROUND

18F-FDG PET/CT imaging represents the most important functional imaging method in oncology. European Society of Medical Oncology and the National Comprehensive Cancer Network guidelines defined a crucial role of 18F-FDG PET/CT imaging for local/locally advanced breast cancer. The application of artificial intelligence on PET images might potentially contributes in the field of precision medicine.

OBJECTIVE

This review aims to summarize the clinical indications and limitations of PET imaging for comprehensive artificial intelligence in relation to breast cancer subtype, hormone receptor status, proliferation rate, and lymphonodal (LN)/distant metastatic spread, based on recent literature.

METHODS

A literature search of the Pubmed/Scopus/Google Scholar/Cochrane/EMBASE databases was carried out, searching for articles on the use of artificial intelligence and PET in breast tumors. The search was updated from January 2010 to October 2021 and was limited to original articles published in English and about humans. A combination of the search terms "artificial intelligence", "breast cancer", "breast tumor", "PET", "Positron emission tomography", "PET/CT", "PET/MRI", "radiomic","texture analysis", "machine learning", "deep learning" was used.

RESULTS

Twenty-three articles were selected following the PRISMA criteria from 139 records obtained from the Pubmed/Scopus/Google Scholar/Cochrane/EMBASE databases according to our research strategy. The QUADAS of 30 full-text articles assessed reported seven articles that were excluded for not being relevant to population and outcomes and/or for lower level of evidence. The majority of papers were at low risk of bias and applicability. The articles were divided per topic, such as the value of PET in the staging and re-staging of breast cancer patients, including new radiopharmaceuticals and simultaneous PET/MRI.

CONCLUSION

Despite the current role of AI in this field remains still undefined, several applications for PET/CT imaging are under development, with some preliminary interesting results particularly focused on the staging phase that might be clinically translated after further validation studies.

Pulmonary transit time of cardiovascular magnetic resonance perfusion scans for quantification of cardiopulmonary haemodynamics

AIMS

Pulmonary transit time (PTT) is the time blood takes to pass from the right ventricle to the left ventricle via pulmonary circulation. We aimed to quantify PTT in routine cardiovascular magnetic resonance imaging perfusion sequences. PTT may help in the diagnostic assessment and characterization of patients with unclear dyspnoea or heart failure (HF).

METHODS AND RESULTS

We evaluated routine stress perfusion cardiovascular magnetic resonance scans in 352 patients, including an assessment of PTT. Eighty-six of these patients also had simultaneous quantification of N-terminal pro-brain natriuretic peptide (NTproBNP). NT-proBNP is an established blood biomarker for quantifying ventricular filling pressure in patients with presumed HF. Manually assessed PTT demonstrated low inter-rater variability with a correlation between raters >0.98. PTT was obtained automatically and correctly in 266 patients using artificial intelligence. The median PTT of 182 patients with both left and right ventricular ejection fraction >50% amounted to 6.8 s (Pulmonary transit time: 5.9-7.9 s). PTT was significantly higher in patients with reduced left ventricular ejection fraction (<40%; P < 0.001) and right ventricular ejection fraction (<40%; P < 0.0001). The area under the receiver operating characteristics curve (AUC) of PTT for exclusion of HF (NT-proBNP <125 ng/L) was 0.73 (P < 0.001) with a specificity of 77% and sensitivity of 70%. The AUC of PTT for the inclusion of HF (NT-proBNP >600 ng/L) was 0.70 (P < 0.001) with a specificity of 78% and sensitivity of 61%.

CONCLUSION

PTT as an easily, even automatically obtainable and robust non-invasive biomarker of haemodynamics might help in the evaluation of patients with dyspnoea and HF.

The Calcium Score's power of zero in 82-Rubidium PET depending on age group and sex

Background

Coronary calcium score (CAC) is a well-validated method to detect coronary artery disease (CAD). A significant number of patients referred for functional ischaemia tests reveal a normal result. CAC could be a potential gatekeeper to reduce unnecessary testing.

Purpose

Study aims were to describe the frequency of zero calcium and its diagnostic power to exclude abnormal perfusion stratified by age and sex in a large cohort undergoing 82-Rubidium Positron Emission Tomography (PET).

Methods

All consecutive patients with suspected CAD who were referred for myocardial perfusion PET at our tertiary center between 2016 and 2021 were identified. Baseline and scan related data were extracted from the electronic database. Patients were included for this retrospective analysis if CAC and semi-quantitative analysis of perfusion study were available. Percentiles and test characteristics of zero calcium were calculated stratified by age and sex. Summed stress score (SSS) ≥4 on PET was considered abnormal.

Results

2640 patients were included. Mean age was 65±11 years; 54% were male. Angina and dyspnea were present in 39% and 60%, respectively. 21% (558/2640) of the scans were abnormal and median CAC was 62 [0–374]. 685 patients (26%) had no calcium. Stratified by age, the proportion of zero calcium was 89% (&lt;40 years), 61% (40–49y), 40% (50–59y), 21% (60–69y), 14% (70–79y) and 6% (≥80y). CAC was higher in abnormal scans (median 561 vs. 27, p&lt;0.001) and zero CAC was associated with a lower risk of abnormal PET (2.6% vs. 27.6%, p&lt;0.001). The negative predictive value (NPV) of calcium zero to exclude abnormal PET was 97%, 96% and 98% for all patients, males and females, respectively. Test characteristics are displayed in Table 1. Percentiles of CAC according to scan result are depicted in Figure 1.

Conclusion

The proportion of zero calcium is frequent and declines with increasing age. The absence of coronary calcium is associated with less abnormal PET scans. Zero calcium to exclude an abnormal scan performed best in young patients (&lt;50) with a NPV ≥98%. CAC could act as a gatekeeper. However, further studies including safety endpoints are needed.

The upper calcium score indicates the 90th percentile of patients with normal PET. The lower calcium score indicates the 5th percentile of patients with abnormal PET. Calcium scores within the white area are unlikely to be associated with abnormal PET (since this area includes only the 5% of abnormal PET scans). The dark grey area indicates patients with a high likelihood of positive PET. For better readability, different scales were used.

Funding Acknowledgement

Type of funding sources: None.

Left ventricular ejection fraction, myocardial blood flow and hemodynamic variables in adenosine and regadenoson vasodilator 82-Rubidium PET

AIMS

In most Rubidium-(Rb)-positron emission tomography (PET) studies, dipyridamole was used as vasodilator. The aim was to evaluate vasodilator PET left ventricular ejection fraction (LVEF), myocardial blood flow (MBF), hemodynamics, and the influence of adenosine and regadenoson on these variables.

METHODS AND RESULTS

Consecutive patients (N = 2299) with prior coronary artery disease (CAD) or no prior CAD undergoing adenosine/regadenoson 82Rb-PET were studied and compared according to CAD status and normal/abnormal PET (summed stress score 0-3 vs. ≥4). Rest and stress LVEF differed significantly depending on CAD status and scan results. In patients with no prior CAD, rest/stress LVEF were 68% and 72%, in patients with prior CAD 60% and 63%. LVEF during stress increased 5 ± 6% in normal compared to 1 ± 8% in abnormal PET (P<0.001). Global rest myocardial blood flow(rMBF), stress MBF(sMBF) and myocardial flow reserve (sMBF/rMBF) were significantly higher in no prior CAD patients compared to prior CAD patients(1.3 ± 0.5, 3.3 ± 0.9, 2.6 ± 0.8 and 1.2 ± 0.4, 2.6 ± 0.8, 2.4 ± 0.8 ml/g/min, respectively, P<0.001) and in normal versus abnormal scans, irrespective of CAD status(no prior CAD: 1.4 ± 0.5, 3.5 ± 0.8, 2.8 ± 0.8 and 1.2 ± 0.8, 2.5 ± 0.8, 2.2 ± 0.7; prior CAD: 1.3 ± 0.4, 3.1 ± 0.8, 2.7 ± 0.8 and 1.1 ± 0.4, 2.3 ± 0.7, 2.2 ± 0.7 ml/g/min, respectively, P<0.001). LVEF and hemodynamic values were similar for adenosine and regadenoson stress. Stress LVEF ≥70% excluded relevant ischemia (≥10%) with a negative predictive value (NPV) of 94% (CI 92-95%).

CONCLUSIONS

Rest/stress LVEF, LVEF reserve and MBF values are lower in abnormal compared to normal scans. Adenosine and regadenoson seem to have similar effect on stress LVEF, MBF and hemodynamics. A stress LVEF ≥70% has a high NPV to exclude relevant ischemia.

Quantitative myocardial perfusion 82Rb-PET assessed by hybrid PET/coronary-CT: Normal values and diagnostic performance

PURPOSE

We aimed to assess normal values for quantified myocardial blood flow (MBF) on a hybrid PET/coronary-CT scanner and to test their diagnostic performance in patients with suspected CAD.

MATERIALS AND METHODS

Patients underwent 82Rb-PET/CT and integrated CT-based coronary angiography (CCTA) and were classified as normal (no stenosis), with non-obstructive stenosis (< 50%) and with CAD (≥ 50%). Global and regional stress MBF (sMBF), rest MBF and myocardial flow reserve (MFR) were calculated. Ischemia was defined as SDS ≥ 2, severe ischemia as SDS ≥ 7.

RESULTS

357 consecutive patients were included. Global sMBF and MFR were higher in normal patients than in patients with CAD (3.61 ± 0.71 vs 3.04 ± 0.77, P < 0.0001; 3.08 ± 0.84 vs 2.68 ± 0.79, P = 0.0001), but not different compared to patients with non-obstructive stenosis (3.61 ± 0.71 vs 3.43 ± 0.69, P = 0.052; 3.08 ± 0.84 vs 2.99 ± 0.82, P = 0.45). sMBF yielded superior accuracy over MFR in identifying both ischemia (AUC 0.74 vs 0.62, P = 0.003) and severe ischemia (AUC 0.88 vs 0.78, P = 0.012). Optimal threshold for global sMBF to rule out myocardial ischemia was 3.5 mL g-1 min-1.

CONCLUSIONS

Normal quantitative values are provided. Global sMBF provided higher diagnostic accuracy than MFR. Using sMBF-threshold of 3.5 mL·g-1·min-1 on 82Rb-PET/CT yielded similar NPV (96%) as CCTA to rule out CAD. Hence, resting scan could be omitted in patients with sMBF values above reference.

The role of cardiovascular magnetic resonance in the evaluation of acute myocarditis and inflammatory cardiomyopathies in clinical practice - a comprehensive review

Inflammatory cardiomyopathy (I-CMP) is defined as myocarditis in association with cardiac dysfunction and/or ventricular remodelling. It is characterized by inflammatory cell infiltration into the myocardium and has heterogeneous infectious and non-infectious aetiologies. A complex interplay of genetic, autoimmune, and environmental factors contributes to the substantial risk of deteriorating cardiac function, acute heart failure, and arrhythmia as well as chronic dilated cardiomyopathy and its sequelae. Multi-parametric cardiovascular magnetic resonance (CMR) imaging is sensitive to many tissue changes that occur during myocardial inflammation, regardless of its aetiology. In this review, we summarize the various aetiologies of I-CMP and illustrate how CMR contributes to non-invasive diagnosis.

Artificial intelligence approach improves ischaemia prediction beyond the known pretest probability scores

Background

Pre-test probability (PTP) assessment is crucial in the assessment of patients with suspected ischaemia/coronary artery disease. Presently there is no established role for artificial intelligence in estimating PTP.

Purpose

Comparison of a recently developed memetic pattern based algorithm (MPA) with the diagnostic power of established scores in predicting ischaemia on positron emission tomography myocardial perfusion imaging (PET MPI).

Methods

Consecutive patients undergoing Rubidium PET MPI for routine clinical evaluation of ischaemia were included. The PTP for each patient was estimated by MPA, the Diamond and Forrester scores (DFS), the PTP models from the European Society of Cardiology Guidelines from 2013 (ESC 2013) and 2019 (ESC 2019) and the Framingham scores (FRS). The PET MPI studies were assessed for the presence of ischaemia. Ischaemia was defined as a summed difference score (SDS) ≥2.

Results

The mean age of the 531 patients was 66±11 years, 34% were female, and 50% had known prior coronary artery disease; 208 patients had evidence of ischaemia. No ischaemia was found in 323 patients. The areas under the curve (AUC) are shown in the figure. The artificial intelligence based MPA provided an AUC of 0.76, PTP (ESC 2013) AUC of 0.67, PTP (ESC 2019) AUC 0.67, DFS AUC 0.56, FRS 0.68.

Conclusion

The MPA outperforms the established scores for PTP assessment of the ESC, DFS and FRS in prediction of ischaemia on PET MPI. It has the potential to improve the accuracy of the established diagnostic algorithm for CAD and ischaemia.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The study was in part funded by the Swiss Heart Foundation.

Bilateral proximal hamstring muscle avulsion after treatment with immune checkpoint inhibitors and corticosteroids

A 66-year-old man presented with 4 weeks of bilateral buttock pain without previous trauma or intense exercise. He had been treated with immune checkpoint inhibitors because of metastasising melanoma and experienced immune-related adverse events requiring treatment with corticosteroids. Magnetic resonance imaging of the pelvis revealed bilateral avulsion of the proximal hamstring muscles. Treatment with physical therapy and nonsteroidal anti-inflammatory drugs led to a slow but lasting relief. This is, to our knowledge, the first report of symptomatic non-traumatic bilateral hamstring muscle avulsion following treatment with immune checkpoint inhibitors and corticosteroids.

The role of 18F-Fluorodeoxyglucose PET/CT in restaging patients with small cell lung cancer: a systematic review

AIM

18F-Fluorodeoxyglucose (FDG) PET imaging may play an important role in the restaging of patients with small-cell lung cancer (SCLC),, nevertheless, a systematic review of literature was still missing in this setting. The aim of this review was to summarize the evidence on literature regarding the utility of 18F-FDG PET imaging in restaging patients with SCLC.

METHODS

A literature search was performed to retrieve original studies using 18F-FDG PET or 18F-FDG PET/computed tomography (CT) in a minimum of 10 patients with SCLC at restaging.

RESULTS

The selected literature (17 studies) was discussed in four sections: detection rate, impact on management, prediction of prognosis and evaluation of the response to therapy. According to the literature, PET imaging may result in discordance with conventional imaging, mainly contrast-enhanced CT (ceCT), and detect additional lesions in a certain proportion of cases, leading to upstaging or downstaging. A variable level of disagreement between PET and conventional imaging has been reported also in the evaluation of response to therapy. A positive PET study is associated with shorter survival, especially in the presence of distant metastases. According to some studies, semiquantitative parameters are also inversely associated with overall survival and progression-free survival. Although the retrieved articles proved the utility of 18F-FDG PET imaging in each clinical setting, literature is still limited.

CONCLUSIONS

This review encourages the use of 18F-FDG PET imaging, especially in conjunction with ceCT in recurrent SCLC patients. Further level I evidence is needed to further assess the diagnostic and prognostic capability of 18F-FDG PET/ceCT findings in SCLC.

Influence of adenosine and regadenoson on left ventricular ejection fraction, myocardial blood flow and hemodynamics in vasodilator 82-Rubidium PET

Funding Acknowledgements

Type of funding sources: None.

Introduction

Most 82Rubidium-(Rb)-Positron emission tomography (PET) studies for myocardial perfusion, dipyridamole was used as vasodilator. Less data is available for adenosine and regadenoson.

Purpose

Therefore, the aim was to evaluate the influence of adenosine and regadenoson on left ventricular ejection fraction (LVEF), myocardial blood flow (MBF) and hemodynamics in vasodilator 82Rb-PET.

Methods

Consecutive patients (n = 2299) with suspected or known coronary artery disease (CAD) undergoing 82Rb-PET were studied and compared according to CAD status and normal/abnormal PET (abnormal defined as summed stress score ≥4). Differences between stress and rest values (LVEF, MBF, hemodynamics) were calculated. The threshold of stress LVEF able to exclude a relevant ischemia (as defined by ≥10% myocardium ischemic based on SDS score) was assessed.

Results

Rest and stress LVEF differed significantly depending on CAD status and scan results. In patients with suspected CAD, rest/stress LVEF were 68 ± 12% and 73 ± 12% (p &lt; 0.001), in patients with prior CAD 60 ± 14% and 63 ± 15% (p &lt; 0.001). LVEF during stress increased 5 ± 6% in normal compared to 1 ± 8% in abnormal PET (p &lt; 0.001). Global rest MBF (rMBF), stress MBF (sMBF) and myocardial flow reserve (sMBF/rMBF) were significantly higher in suspected CAD patients compared to prior CAD patients (1.3 ± 0.5, 3.3 ± 0.9, 2.6 ± 0.8 and 1.2 ± 0.4, 2.6 ± 0.8, 2.4 ± 0.8 ml/g/min, respectively, p &lt; 0.001), and in normal versus abnormal scans, irrespective of CAD status (no CAD: 1.4 ± 0.5, 3.5 ± 0.8, 2.8 ± 0.8 and 1.2 ± 0.8, 2.5 ± 0.8, 2.2 ± 0.7; known CAD: 1.3 ± 0.4, 3.1 ± 0.8, 2.7 ± 0.8 and 1.1 ± 0.4, 2.3 ± 0.7, 2.2 ± 0.7 ml/g/min, respectively, p &lt; 0.001). LVEF and hemodynamic values were similar for adenosine and regadenoson stress. Stress LVEF ≥70% excluded relevant ischemia with a negative predictive value (NPV) of 94% (CI 92-95%).

Conclusions

Rest/stress LVEF, LVEF reserve and MBF values are lower in abnormal compared with normal scans. Adenosine and regadenoson seem to have similar effect on stress LVEF, MBF and hemodynamics. A stress LVEF ≥70% has a high NPV to exclude relevant ischemia.

Accuracy comparison of various quantitative [99mTc]Tc-DPD SPECT/CT reconstruction techniques in patients with symptomatic hip and knee joint prostheses

BACKGROUND

There is a need for better diagnostic tools that identify loose total hip and knee arthroplasties. Here, we present the accuracy of different 99mTc-dicarboxypropandiphosphate ([99mTc]Tc-DPD) SPECT/CT quantification tools for the detection of loose prostheses in patients with painful hip and knee arthroplasties.

METHODS

Quantitative reconstruction of mineral phase SPECT data was performed using Siemens xSPECT-Quant and xSPECT-Bone, with and without metal artefact reduction (iMAR) of CT-data. Quantitative data (SUVmax values) were compared to intraoperative diagnosis or clinical outcome after at least 1 year as standard of comparison. Cut-off values and accuracies were calculated using receiver operator characteristics. Accuracy of uptake quantification was compared to the accuracy of visual SPECT/CT readings, blinded for the quantitative data and clinical outcome.

RESULTS

In this prospective study, 30 consecutive patients with 33 symptomatic hip and knee prostheses underwent [99mTc]Tc-DPD SPECT/CT. Ten arthroplasties were diagnosed loose and 23 stable. Mean-SUVmax was significantly higher around loose prostheses compared to stable prostheses, regardless of the quantification method (P = 0.0025-0.0001). Quantification with xSPECT-Bone-iMAR showed the highest accuracy (93.9% [95% CI 79.6-100%]) which was significantly higher compared to xSPECT-Quant-iMAR (81.8% [67.5-96.1%], P = 0.04) and xSPECT-Quant without iMAR (77.4% [62.4-92.4%], P = 0.02). Accuracies of clinical reading were non-significantly lower compared to quantitative measures (84.8% [70.6-99.1%] (senior) and 81.5% [67.5-96.1%] (trainee)).

CONCLUSION

Quantification with [99mTc]Tc-DPD xSPECT-Bone-iMAR discriminates best between loose and stable prostheses of all evaluated methods. The overall high accuracy of different quantitative measures underlines the potential of [99mTc]Tc-DPD-quantification as a biomarker and demands further prospective evaluation in a larger number of prosthesis.

Colonic delivery of metronidazole-loaded capsules for local treatment of bacterial infections: A clinical pharmacoscintigraphy study

Drug delivery to the colon offers great promise for local treatment of colonic diseases as it allows bypassing systemic absorption in the small intestine, thereby increasing luminal drug concentrations in the colon. The primary objective of this in vivo pharmaco-scintigraphy study was to assess the colon drug targeting accuracy of a metronidazole benzoate colonic drug delivery system intended for local treatment of Clostridioides difficile infections. Additionally, it was assessed if the concept of mucoadhesion would increase colonic residence time and promote higher drug bioavailability. Two different capsule formulations were designed and tested in healthy human subjects. Capsules contained either non-mucoadhesive (NM) or mucoadhesive (M) microgranules, both loaded with 100 mg metronidazole benzoate (antibiotic prodrug) and 5 mg samarium oxide (scintigraphy tracer). Filled capsules were coated with a colonic-targeting technology consisting of two functional layers, which allow for accelerated drug release mediated by the intestinal pH in combination with colonic bacteria. Coated capsules were neutron-activated to yield the radioisotope ¹⁵³Sm prior to administration to 18 healthy subjects. Gamma-scintigraphy imaging was combined with the measurement of drug plasma levels. Formulation NM showed high colon-targeting accuracy. Initial capsule disintegration within the targeted ileocolonic region was observed in 8 out of 9 subjects (89%) with colonic arrival times in the range of 3.5-12 h and reduced systemic exposure. In contrast, the mucoadhesive formulation M showed some inconsistency regarding the site of initial capsule disintegration (targeting accuracy 56%). Variability of drug release was attributed to self-adhesion and agglomeration of the mucoadhesive microparticles within the capsule. Accurate ileocolonic delivery of metronidazole-loaded microgranules was achieved following oral administration of colonic-targeted capsules. Delayed drug release from NM microparticles in the colon leads to a reduced systemic exposure compared to immediate-release data from literature and presumably elevated drug concentrations in the colonic lumen. This approach offers promising options for the local treatment of colonic diseases.

Prognostic value of myocardial perfusion scintigraphy in asymptomatic patients with diabetes mellitus at high cardiovascular risk: 5-year follow-up of the prospective multicenter BARDOT trial

Background

The Basel Asymptomatic High-Risk Diabetics’ Outcome Trial (BARDOT) demonstrated that asymptomatic diabetic patients with an abnormal myocardial perfusion scintigraphy (MPS) were at increased risk of major adverse cardiovascular events (MACEs) at 2-year follow-up. It remains unclear whether this finding holds true even for a longer follow-up.

Methods

Four hundred patients with type 2 diabetes, neither history nor symptoms of coronary artery disease (CAD), were evaluated clinically and with MPS. Patients were followed up for 5 years. Major adverse cardiovascular events (MACEs) were defined as all-cause death, myocardial infarction, or late coronary revascularization.

Results

At baseline, an abnormal MPS (SSS ≥ 4 or SDS ≥ 2) was found in 87 of 400 patients (22%). MACE within 5 years occurred in 14 patients with abnormal MPS (16.1%) and in 22 with normal scan (1.7%), p = 0.009; 15 deaths were recorded. Patients with completely normal MPS (SSS and SDS = 0) had lower rates of MACEs than patients with abnormal scans (2.5% vs. 7.0%, p = 0.032). Patients with abnormal MPS who had undergone revascularization had a lower mortality rate and a better event-free survival from MI and revascularization than patients with abnormal MPS who had either undergone medical therapy only or could not be revascularized (p = 0.002).

Conclusions

MPS may have prognostic value in asymptomatic diabetic patients at high cardiovascular risk over a follow-up period of 5 years. Patients with completely normal MPS have a low event rate and may not need retesting within 5 years. Patients with an abnormal MPS have higher event rates and may benefit from a combined medical and revascularization approach.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05349-5.

Assessment of the warranty period of a normal myocardial perfusion scintigraphy in patients with diabetes mellitus: 5 year follow-up of the prospective multicenter BARDOT trial

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swiss National Foundation for Research

Background

Asymptomatic diabetic patients with an abnormal myocardial perfusion scintigraphy (MPS) are known to be at an increased risk of major cardiac events (MACE) at 2-years follow-up. It remains unclear whether this finding holds true even for a follow-up of 5 years.

Methods

four hundred patients with type-2 diabetes without coronary artery disease were evaluated clinically and with MPS and followed up for 5 years. Major adverse cardiovascular events (MACE) were defined as cardiac death, myocardial infarction or late coronary revascularization. 

Results

 An abnormal MPS (SSS≥4 or SSS≥2) was found in 87 patients (21.8%). MACE within 5 years occurred in 14 patients with abnormal MPS (16.1%) and in 22 with normal scan (1.7%, p = 0.009); 15 deaths were recorded (3.8%). Patients with normal MPS had lower rates of MACEs than patients with abnormal scans (p = 0.016) (Figure 1A + B). Patients with abnormal MPS who had undergone revascularization had a lower mortality rate and a better event free survival from MI and revascularization than patients with abnormal MPS who had either undergone medical therapy only or could not be revascularized (Figure 1C + D). 

Conclusions

Patients with  normal MPS have a low event rate and may not need retesting within 5 years (warranty period). Patients with an abnormal MPS have higher event rates and may benefit from a combined medical and revascularization approach.

Abstract Figure 1 A-D

Prediction of coronary artery disease in positron emission tomography using machine learning algorithms with clinical data and calcium score

Funding Acknowledgements

Type of funding sources: None.

Background

Patients with clinical suspicion of obstructive coronary artery disease (OCAD) are frequently referred for myocardial perfusion imaging (MPI). However, many are at low-to-moderate risk, and have normal MPI. A predictive model may help to identify patients who may not need MPI.

Purpose

To develop novel prediction models for OCAD using machine learning and to compare their performance to a clinical score and to coronary artery calcium score (CACS) to identify patients without OCAD.

Methods

All consecutive patients undergoing 82Rb MPI positron emission tomography (PET) from 2016 to 2020 at our centre and without prior OCAD were enrolled. As clinical data, we recorded age, gender, body mass index, cardiovascular risk factors, chest pain type and dyspnoea. CACS was measured on low-dose computed tomography scans in Agatston units (AU). OCAD was defined as a summed stress score ≥4 in PET. The patient sample was randomly split into a 70% derivation sample and a 30% validation sample. Using 22 different machine learning algorithms, we developed models based on clinical data and based on clinical data + CACS to predict OCAD in the derivation sample, with manual optimization and multiple cross-validation. Then, models were evaluated in the validation sample to select the highest area under the receiver operating characteristic curve (AUC, with 95% confidence intervals). Finally, the best models were compared to the pre-test probability of the European Society of Cardiology (PTP-ESC) and to CACS alone in the complete sample for AUC and for patients predicted as free of OCAD, using cut-offs at 95% sensitivity and Fisher’s exact test.

Results

We included 1426 patients (1000 for derivation and 426 for validation). Mean age was 64.3 years (standard deviation 11.3), median CACS 58 AU (interquartile range 363), 780 patients were male (54.7%), and 303 had OCAD on PET (21.2%). In model development, "extreme gradient boosting" (XGBoost) emerged as the best algorithm to predict OCAD with clinical data (AUC 0.74 [0.68-0.80]), and with clinical data + CACS (AUC 0.84 [0.80-0.88], P &lt; 0.001 vs. XGBoost clinical, P &lt; 0.001 vs. logistic regression). In the complete sample, PTP-ESC had an AUC of 0.67 (0.64-0.70), XGBoost clinical 0.75 (0.72-0.78), CACS 0.81 (0.78-0.84), and XGBoost clinical + CACS 0.86 (0.84-0.88), with all P &lt; 0.001 (see Figure). PTP-ESC identified 17% of total patients as OCAD-free with a negative predictive value (NPV) of 93%, XGBoost clinical 24% as OCAD-free with NPV 96%, CACS 33% as OCAD-free with NPV 97%, and XGBoost clinical + CACS 41% as OCAD-free with NPV 97%, with all P &lt; 0.001.

Conclusion

In patients referred for MPI with PET, machine learning using XGBoost can generate powerful predictive models based on clinical data and CACS to identify patients free of OCAD, better than with PTP-ESC or CACS. Such models may be used as gatekeepers before MPI to reduce radiation burden for patients and costs for the health system.

Abstract Figure. Prediction of OCAD in complete sample

Clinical Impact of 18F-FDG PET/CT in the Diagnostic Workup of Pancreatic Ductal Adenocarcinoma: A Systematic Review

In this review, the performance of fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) in the diagnostic workup of pancreatic ductal adenocarcinoma (PDAC) is evaluated. A comprehensive literature search up to September 2020 was performed, selecting studies with the presence of: sample size ≥10 patients and index test (i.e., “FDG” or “18F-FDG” AND “pancreatic adenocarcinoma” or “pancreas cancer” AND “PET” or “positron emission tomography”). The methodological quality was evaluated using the revised quality assessment of diagnostic accuracy studies (QUADAS-2) tool and presented according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Basic data (authors, year of publication, country and study design), patients’ characteristics (number of enrolled subjects and age), disease phase, type of treatment and grading were retrieved. Forty-six articles met the adopted research criteria. The articles were divided according to the considered clinical context. Namely, besides conventional anatomical imaging, such as computed tomography (CT) and magnetic resonance imaging (MRI), molecular imaging with FDG PET/CT is an important tool in PDAC, for all disease stages. Further prospective studies will be necessary to confirm the cost-effectiveness of such imaging techniques by testing its real potential improvement in the clinical management of PDAC.

Clinical Value of PET/CT in Staging Melanoma and Potential New Radiotracers

BACKGROUND

18F-FDG PET/CT has been suggested as an effective tool to stage patients affected by melanoma. In the latest years, new radiopharmaceuticals have been proposed and the use of hybrid PET/ceCT has emerged.

OBJECTIVE

To review recent evidence on the role of PET/CT in melanoma staging as well as its potential for future developments.

METHODS

A comprehensive computer literature search of PubMed/MEDLINE was carried out to find relevant published articles concerning the feasibility of PET/CT in patients with malignant melanoma.

RESULTS

Some recent studies about potentials and limitations of 18F-FDG PET/CT in staging melanoma, new PET radiotracers beyond 18F-FDG and application of hybrid PET/ceCT have been reviewed and discussed.

CONCLUSION

PET/CT plays an important role in the staging workup of patients affected by melanoma. New radiopharmaceuticals and hybrid PET/ceCT could improve the potential of this diagnostic tool in this field.

Prediction of myocardial ischaemia in position emission tomography with clinical data, coronary artery calcium score and machine learning algorithms

Background

With the present evolution of demographics and medical costs, algorithms able to predict the likelihood of coronary artery disease (CAD) may be valuable gatekeepers before advanced cardiac testing, but their value is unknown.

Purpose

We assessed whether clinical data, with or without coronary artery calcium score (CACS), combined with machine learning algorithms can predict ischaemia in position emission tomography (PET).

Methods

All consecutive patients undergoing 82Rb myocardial perfusion PET with CACS from 2016 to 2019 at our hospital were enrolled. Patients with known CAD were excluded. As clinical data, we used demographics, classical risk factors, chest pain type, dyspnoea and electrocardiogram with pathological Q waves or abnormal repolarization. CACS was measured from low-dose computed tomography scans in Agatston units (AU). Ischaemia was defined as a summed difference score ≥4 in PET. As prediction models, we compared the classical logistic regression, regularized regression (elastic net), decision trees, random forests and a boosting algorithm. The patient cohort was split into a 80% training cohort and a 20% test cohort. Models were carefully optimized with 10-fold cross-validation on the training cohort and applied to the test cohort to assess area under the curve (AUC) for ischaemia with 95% confidence intervals in receiver operating characteristic (ROC) analysis.

Results

We included 927 patients, of which 743 were in the training cohort and 184 in the test cohort. Mean age was 64.3±11.1 years, median CACS 55 AU (interquartile range 358) and 179 patients had ischaemia (19.3%). In the test cohort, we found the following AUC (see Figure): logistic regression with clinical data 0.62 (0.52–0.72, light blue) and CACS 0.73 (0.63–0.82, dark blue) with P=0.012, elastic net regression with clinical data 0.63 (0.54–0.73, light violet) and CACS 0.81 (0.75–0.88, dark violet) with P&lt;0.001, decision trees with clinical data 0.5 (0.5–0.5, light green) and CACS 0.76 (0.68–0.84, dark green) with P&lt;0.001, random forests with clinical data 0.59 (0.48–0.70, light orange) and CACS 0.76 (0.69–0.84, dark orange) with P=0.001, and boosting algorithm with clinical data 0.68 (0.58–0.77, light red) and CACS 0.84 (0.77–0.90, dark red) with P&lt;0.001. Thus, adding CACS substantially improved each prediction model. Compared with classical logistic regression, prediction using clinical data tended to improve with the boosting algorithm (P=0.09). For prediction including CACS, both elastic net regression and the boosting algorithm were superior to logistic regression (P=0.007 and P&lt;0.001).

Conclusion

Prediction of myocardial ischaemia is limited with clinical data only, but can be greatly improved with the use of CACS and machine learning with elastic net regression or a boosting algorithm, reaching a good performance. This approach could be further developed as a gatekeeper to select appropriate patients for further cardiac imaging.

ROC curves: Prediction on test cohort

Funding Acknowledgement

Type of funding source: None

Quantitative 99mTc-DPD SPECT/CT in patients with suspected ATTR cardiac amyloidosis: Feasibility and correlation with visual scores

PURPOSE

While a visual interpretation of 99mTc-DPD scintigraphy by means of Perugini score can provide a reliable diagnosis of transthyretin-related (ATTR) cardiac amyloidosis (CA), a quantitative approach is expected to play a major role in risk stratification and therapy evaluation. The aim of our study was to test the feasibility of a quantitative assessment and to correlate various parameters to Perugini score.

METHODS

in this retrospective study, consecutive patients underwent a 99mTc-DPD whole-body bone scintigraphy and a SPECT/CT of the thorax. XSPECT-QUANT software was used to quantify the DPD uptake in the heart.

RESULTS

Thirteen patients were included. CA was confirmed in 8 and rejected in 5. Myocardial SUVmax and SUVpeak showed a fairly strong correlation with Perugini score (both ρ = .71, P = .006). Same held true for to-bone normalized values (both ρ = .75, P = .003). There was a great degree of overlap for quantitative values in patients with Perugini score 2 and 3.

CONCLUSION

Quantitative 99mTc-DPD SPECT/CT in suspected ATTR CA patients is feasible and allows for a more accurate assessment of myocardial uptake.