Extrahepatic perfusion and incomplete hepatic perfusion after hepatic arterial infusion pump implantation: incidence and clinical implications.

INTRODUCTION: This study investigates the incidence of extrahepatic perfusion and incomplete hepatic perfusion at intraoperative methylene blue testing and on postoperative nuclear imaging in patients undergoing hepatic arterial infusion pump (HAIP) chemotherapy. METHODS: The first 150 consecutive patients who underwent pump implantation in the Netherlands were included. All patients underwent surgical pump implantation with the catheter in the gastroduodenal artery. All patients underwent intraoperative methylene blue testing and postoperative nuclear imaging (99mTc-Macroaggregated albumin SPECT/CT) to determine perfusion via the pump. RESULTS: Patients were included between January-2018 and December-2021 across eight centers. During methylene blue testing, 29.3% had extrahepatic perfusion, all successfully managed intraoperatively. On nuclear imaging, no clinically relevant extrahepatic perfusion was detected (0%, 95%CI: 0.0-2.5%). During methylene blue testing, 2.0% had unresolved incomplete hepatic perfusion. On postoperative nuclear imaging, 8.1% had incomplete hepatic perfusion, leading to embolization in only 1.3%. CONCLUSION: Methylene blue testing during pump placement for intra-arterial chemotherapy identified extrahepatic perfusion in 29.3% of patients, but could be resolved intraoperatively in all patients. Postoperative nuclear imaging found no clinically relevant extrahepatic perfusion and led to embolization in only 1.3% of patients. The role of routine nuclear imaging after HAIP implantation should be studied in a larger cohort.

Diagnostic implications of a small-voxel reconstruction for loco-regional lymph node characterization in breast cancer patients using FDG-PET/CT.

BACKGROUND: We evaluated the diagnostic implications of a small-voxel reconstruction for lymph node characterization in breast cancer patients, using state-of-the-art FDG-PET/CT. We included 69 FDG-PET/CT scans from breast cancer patients. PET data were reconstructed using standard 4 × 4 × 4 mm3 and small 2 × 2 × 2 mm3 voxels. Two hundred thirty loco-regional lymph nodes were included, of which 209 nodes were visualised on PET/CT. All nodes were visually scored as benign or malignant, and SUVmax and TBratio(=SUVmax/SUVbackground) were measured. Final diagnosis was based on histological or imaging information. We determined the accuracy, sensitivity and specificity for both reconstruction methods and calculated optimal cut-off values to distinguish benign from malignant nodes. RESULTS: Sixty-one benign and 169 malignant lymph nodes were included. Visual evaluation accuracy was 73% (sensitivity 67%, specificity 89%) on standard-voxel images and 77% (sensitivity 78%, specificity 74%) on small-voxel images (p = 0.13). Across malignant nodes visualised on PET/CT, the small-voxel score was more often correct compared with the standard-voxel score (89 vs. 76%, p <  0.001). In benign nodes, the standard-voxel score was more often correct (89 vs. 74%, p = 0.04). Quantitative data were based on the 61 benign and 148 malignant lymph nodes visualised on PET/CT. SUVs and TBratio were on average 3.0 and 1.6 times higher in malignant nodes compared to those in benign nodes (p <  0.001), on standard- and small-voxel PET images respectively. Small-voxel PET showed average increases in SUVmax and TBratio of typically 40% over standard-voxel PET. The optimal SUVmax cut-off using standard-voxels was 1.8 (sensitivity 81%, specificity 95%, accuracy 85%) while for small-voxels, the optimal SUVmax cut-off was 2.6 (sensitivity 78%, specificity 98%, accuracy 84%). Differences in accuracy were non-significant. CONCLUSIONS: Small-voxel PET/CT improves the sensitivity of visual lymph node characterization and provides a higher detection rate of malignant lymph nodes. However, small-voxel PET/CT also introduced more false-positive results in benign nodes. Across all nodes, differences in accuracy were non-significant. Quantitatively, small-voxel images require higher cut-off values. Readers have to adapt their reference standards.

Sequential SPECT/CT imaging for detection of coronary artery disease in a large cohort: evaluation of the need for additional imaging and radiation exposure.

BACKGROUND: Performing both single photon emission computerized tomography (SPECT) and coronary computed tomography angiography (CCTA) in patients suspected for coronary artery disease (CAD) leads to increased radiation exposure. We evaluated the need for additional imaging and following implications for radiation exposure of a sequential SPECT/computed tomography (CT) algorithm. METHODS AND RESULTS: 5018 consecutive patients without history of CAD were referred for stress-first SPECT and coronary artery calcium (CAC) scoring. If stress SPECT was abnormal, additional rest SPECT and, if feasible, CCTA were acquired. Stress SPECT was normal in 2617 patients (52%). CCTA was not performed in 1289 of the 2401 patients referred for additional imaging (54%), mainly because of severe CAC (47%) or fast/irregular heart rate (22%). 642 patients with abnormal SPECT underwent CCTA, which excluded significant CAD in 378 patients (59%). Mean radiation dose was 4.5 ± 0.3 mSv for stress-only imaging and 13.2 ± 3.3 mSv for additional imaging (P < 0.001). CONCLUSIONS: Half of the patients do not require additional imaging in our sequential SPECT/CT algorithm, which is accompanied with low radiation exposure. CCTA cannot be performed in half of the patients who undergo additional imaging because of (relative) contra-indications. CCTA is able to correct for false-positive SPECT findings in our algorithm.

Improving the detection of small lesions using a state-of-the-art time-of-flight PET/CT system and small-voxel reconstructions.

UNLABELLED: A major disadvantage of (18)F-FDG PET involves poor detection of small lesions and lesions with low metabolism, caused by limited spatial resolution and relatively large image voxel size. As spatial resolution and sensitivity are better in new PET systems, it is expected that small-lesion detection could be improved using smaller voxels. The aim of this study was to test this hypothesis using a state-of-the-art time-of-flight PET/CT device. METHODS: (18)F-FDG PET scans of 2 image-quality phantoms (sphere sizes, 4-37 mm) and 39 consecutive patients with lung cancer were analyzed on a time-of-flight PET/CT system. Images were iteratively reconstructed with standard 4 × 4 × 4 mm voxels and smaller 2 × 2 × 2 mm voxels. For the phantom study, we determined contrast-recovery coefficients and signal-to-noise ratios (SNRs). For the patient study, (18)F-FDG PET-positive lesions in the chest and upper abdomen with a volume less than 3.0 mL (diameter, <18 mm) were included. Lesion mean and maximum standardized uptake values (SUVmean and SUVmax, respectively) were determined in both image sets. SNRs were determined by comparing SUVmax and SUVmean with background noise levels. A subanalysis was performed for lesions less than 0.75 mL (diameter, <11 mm). For qualitative analysis of patient data, 3 experienced nuclear medicine physicians gave their preference after visual side-by-side analysis. RESULTS: For phantom spheres 13 mm or less, we found higher contrast-recovery coefficients and SNRs using small-voxel reconstructions. For 66 included (18)F-FDG PET-positive lesions, the average increase in SUVmean and SUVmax using the small-voxel images was 17% and 32%, respectively (P < 0.01). For lesions less than 0.75 mL (21 in total), the average increase was 21% and 44%, respectively. Moreover, averaged over all lesions, the mean and maximum SNR increased by 20% and 27%, respectively (P < 0.01). For lesions less than 0.75 mL, these values increased up to 23% and 46%, respectively. The physicians preferred the small-voxel reconstructions in 76% of cases. CONCLUSION: Supported by a phantom study, there was a visual preference toward (18)F-FDG PET images reconstructed with 2 × 2 × 2 mm voxels and a profound increase in standardized uptake value and SNR for small lesions. Hence, it is expected that small-lesion detection improves using small-voxel reconstructions.

Myocardial perfusion imaging in stable symptomatic patients with extensive coronary atherosclerosis.

PURPOSE: High coronary artery calcium (CAC) scores are associated with a high likelihood of ischaemia and obstructive coronary disease. Myocardial perfusion imaging (MPI) is a key investigation to determine the need for revascularization. However, the value of MPI in presence of extensive CAC has so far only been demonstrated in asymptomatic patients, whereas its value in symptomatic patients remains largely unclear. Therefore, we studied the impact of MPI in symptomatic patients with a CAC score ≥ 1,000. METHODS: We included 282 patients (mean age 69 ± 9 years, 63% men) without a history of coronary disease with suspected stable angina referred for MPI and with a CAC score ≥ 1,000. On follow-up at 18 months invasive angiography, coronary revascularization, nonfatal myocardial infarction and death were recorded. RESULTS: MPI was normal in 54 %, equivocal in 10 % and abnormal in 37 % (fixed defect 9 % and ischaemia 28 %) of patients. More abnormal MPI findings were observed in men, smokers and those with even higher CAC scores. During follow-up, 1 patient (with nonischaemic MPI) died from a cardiac cause, 1 patient (with ischaemic MPI) suffered a myocardial infarction and 92 patients (33 %) underwent revascularization. Ischaemia on MPI was a strong predictor of coronary revascularization (odds ratio 13.1; 95 % CI 7.1-24.3; p < 0.001). CONCLUSION: Ischaemia on MPI is observed in approximately 30 % of patients with a CAC score ≥ 1,000, and is a strong predictor of coronary revascularization. However, nonischaemic MPI does not exclude revascularization, and patients with persisting complaints should be considered for invasive angiography.

Myocardial perfusion imaging with a cadmium zinc telluride-based gamma camera versus invasive fractional flow reserve.

PURPOSE: Recently introduced ultrafast cardiac SPECT cameras with cadmium zinc telluride-based (CZT) detectors may provide superior image quality allowing faster acquisition with reduced radiation doses. Although the level of concordance between conventional SPECT and invasive fractional flow reserve (FFR) measurement has been studied, that between FFR and CZT-based SPECT is not yet known. Therefore, we aimed to assess the level of concordance between CZT SPECT and FFR in a large patient group with stable coronary artery disease. METHODS: Both invasive FFR and myocardial perfusion imaging with a CZT-based SPECT camera, using Tc-tetrofosmin as tracer, were performed in 100 patients with stable angina and intermediate grade stenosis on invasive coronary angiography. A cut-off value of <0.75 was used to define abnormal FFR. RESULTS: The mean age of the patients was 64 ± 11 years, and 64 % were men. SPECT demonstrated ischaemia in 31 % of the patients, and 20 % had FFR <0.75. The concordance between CZT SPECT and FFR was 73 % on a per-patient basis and 79 % on a per-vessel basis. Discordant findings were more often seen in older patients and were mainly (19 %) the result of ischaemic SPECT findings in patients with FFR ≥ 0.75, whereas only 8 % had an abnormal FFR without ischaemia as demonstrated by CZT SPECT. CONCLUSION: Only 20 - 30 % of patients with intermediate coronary stenoses had significant ischaemia as assessed by CZT SPECT or invasive FFR. CZT SPECT showed a modest degree of concordance with FFR, which is comparable with previous results with conventional SPECT. Further investigations are particularly necessary in patients with normal SPECT and abnormal FFR, especially to determine whether these patients should undergo revascularization.

The influence of coronary calcium score on the interpretation of myocardial perfusion imaging.

PURPOSE: Coronary artery calcium (CAC) scores influence the pre-test likelihood of ischemia in patients undergoing myocardial perfusion imaging (MPI). We investigated the influence of CAC score knowledge on the visual interpretation of MPI in patients referred for the diagnostic work-up of suspected coronary artery disease. METHODS: We retrospectively analyzed symptomatic patients who were referred for MPI. For the current analysis, we selected 151 patients who underwent SPECT MPI with simultaneous CAC scoring. MPI was visually interpreted in two separate sessions, first without and then with knowledge of the CAC score. MPI results were classified into four groups: normal, fixed defects, ischemia, and equivocal. RESULTS: Mean age of the patients was 64 ± 11 years, 56% were male. Without knowledge of the CAC score MPI was evaluated as normal in 36%, compared to 40% with knowledge of the CAC score (P = 0.636). Overall, the addition of the CAC score changed the interpretation of MPI in 56 patients (37%). Importantly, the frequency of equivocal MPI interpretations decreased from 21% without knowledge of CAC score to 9% with knowledge of CAC score (P = 0.002). CONCLUSIONS: Knowledge of the CAC score has a major impact on the interpretation of MPI, increasing the interpretative certainty.

Coronary artery calcium scoring to exclude flow-limiting coronary artery disease in symptomatic stable patients at low or intermediate risk.

PURPOSE: To assess the capability of a zero coronary artery calcium (CAC) score to help exclude flow-limiting coronary artery disease (CAD) in a homogeneous population with stable anginal complaints and a low-to-intermediate pretest likelihood. MATERIALS AND METHODS: The study protocol had institutional ethics committee approval, with written informed consent from all patients. Between 2009 and 2011, a total of 3501 consecutive stable patients without known CAD underwent prospectively simultaneous myocardial perfusion imaging and CAC scoring on a hybrid, 64-section single photon emission computed tomography (SPECT)/computed tomography (CT) scanner. In 868 (25%) of 3501 patients, the CAC score was zero, and these patients constituted the current study population. When feasible, additional coronary CT angiography was performed in those with abnormal SPECT findings. Clinical follow-up was recorded with regard to invasive coronary angiography, coronary revascularization, nonfatal myocardial infarction, or death. Results were analyzed by using descriptive statistics. RESULTS: In 868 patients (mean age, 54 years ± 11 [standard deviation]; 610 [70%] female, 258 [30%] male), SPECT findings were normal in 766 (88%) and abnormal in 102 (12%), with equivocal results in 41 (5%), persistent defect in 35 (4%), and ischemia in 26 (3%). In the group with abnormal SPECT findings, additional coronary CT angiography was performed in 93 patients (91%), showing nonobstructive CAD in eight patients (9%) and normal coronary arteries in 85 patients (91%). In the other nine patients (9%), invasive angiography was used to exclude obstructive CAD. At a median follow-up of 17 months (25th percentile, 11; 75th percentile, 24 months), no coronary events were recorded. CONCLUSION: A CAC score of zero in stable patients at low or intermediate risk excludes flow-limiting CAD. These findings support the possibility of CAC scoring as a simple and safe tool to select patients for additional testing or discharge, as recommended in the literature.

Impact of a new ultrafast CZT SPECT camera for myocardial perfusion imaging: fewer equivocal results and lower radiation dose.

PURPOSE: The new ultrafast cardiac single photon emission computed tomography (SPECT) cameras with cadmium-zinc-telluride (CZT)-based detectors are faster and produce higher quality images as compared to conventional SPECT cameras. We assessed the need for additional imaging, total imaging time, tracer dose and 1-year outcome between patients scanned with the CZT camera and a conventional SPECT camera. METHODS: A total of 456 consecutive stable patients without known coronary artery disease underwent myocardial perfusion imaging on a hybrid SPECT/CT (64-slice) scanner using either conventional (n = 225) or CZT SPECT (n = 231). All patients started with low-dose stress imaging, combined with coronary calcium scoring. Rest imaging was only done when initial stress SPECT testing was equivocal or abnormal. Coronary CT angiography was subsequently performed in cases of ischaemic or equivocal SPECT findings. Furthermore, 1-year clinical follow-up was obtained with regard to coronary revascularization, nonfatal myocardial infarction or death. RESULTS: Baseline characteristics were comparable between the two groups. With the CZT camera, the need for rest imaging (35 vs 56%, p < 0.001) and additional coronary CT angiography (20 vs 28%, p = 0.025) was significantly lower as compared with the conventional camera. This resulted in a lower mean total administered isotope dose per patient (658 ± 390 vs 840 ± 421 MBq, p < 0.001) and shorter imaging time (6.39 ± 1.91 vs 20.40 ± 7.46 min, p < 0.001) with the CZT camera. After 1 year, clinical outcome was comparable between the two groups. CONCLUSION: As compared to images on a conventional SPECT camera, stress myocardial perfusion images acquired on a CZT camera are more frequently interpreted as normal with identical clinical outcome after 1-year follow-up. This lowers the need for additional testing, results in lower mean radiation dose and shortens imaging time.

[Hybrid cardiac SPECT-CT for coronary heart disease]. / Hybride cardio-SPECT-CT voor de diagnostiek van coronairlijden.

Cardiac SPECT-CT is a new hybrid technique that simultaneously produces non-invasive functional information (SPECT) and anatomical information about the coronary arteries (CT). Both types of information are crucial for optimal decision making regarding coronary revascularisation. The hybrid SPECT-CT scanner is very suitable for individual patient-tailored algorithms in which SPECT based ischaemia detection can be complemented with CT coronary angiography or vice-versa. In such approaches CT corrects the limitations of SPECT and SPECT corrects the limitations of CT. Initial studies report high diagnostic performance. The SPECT-CT technique is fast, comprehensive, efficient and even financially advantageous. SPECT-CT probably contributes to a more efficient use of invasive diagnostic coronary angiography.

Ruling out clinically suspected pulmonary embolism by assessment of clinical probability and D-dimer levels: a management study.

D-dimer test combined with clinical probability assessment has been proposed as the first step in the diagnostic work-up of patients with suspected pulmonary embolism (PE). In a prospective management study we investigated the safety and efficiency of excluding PE by a normal D-dimer combined with a low or moderate clinical probability. Of the 202 study patients this combination ruled out PE in 64 (32%) patients. The 3-month thromboembolic risk in these patients was 0% (95% CI, 0.0-5.6%). The prevalence of PE in the entire cohort was 29% (59 patients), whereas in the low, moderate and high clinical probability groups this was 25%, 26% and 50%, respectively. We conclude that ruling out suspected PE by a normal D-dimer combined with a low or moderate clinical probability appears to be a safe and efficient strategy. The accuracy of the clinical probability assessment is modest.