Procedure guidelines for radionuclide myocardial perfusion imaging: (Adopted by the British Cardiac Society, the British Nuclear Cardiology Society, and the British Nuclear Medicine Society)

The additive prognostic value of coronary calcium score (CCS) to single photon emission computed tomography myocardial perfusion imaging (SPECT-MPI)-real world data from a single center

AIMS

Single-photon emission computed tomography myocardial perfusion imaging [SPECT-MPI] is a functional test for coronary ischemia. We aimed to assess the additive prognostic value of coronary calcium score (CCS) to SPECT-MPI in stable patients.

METHODS

This study is a retrospective analysis of 655 patients who underwent SPECT-MPI with CCS (2012 to 2017). Receiver operator characteristic (ROC) identified CCS cutoff value for all-cause mortality: CCS+ if > cutoff value and MPI+ if ≥ 5% total perfusion defect (TPD). Patients were divided into 1 MPI-/CCS-; 2 MPI+/CCS-; 3 MPI-/CCS+; 4 MPI+/CCS+ and compared. Cox proportional hazard analysis identified predictors of mortality.

RESULTS

CCS cutoff for all-cause mortality was > 216 (C statistic 0.756, P < 0.0001). In MPI+ groups, mean TPD was similar (13.4% and 13.1% respectively) but mortality was higher in the CCS+ (12.5% vs. 4.8%, P = 0.22) as was the severe LV systolic dysfunction (8.0% vs. 0%, P = 0.095). In MPI- groups, mean TPD was similar (0.7% and 0.9% respectively) but all-cause mortality was higher in the CCS+ (10.7% vs. 1.6%, P < 0.0001) as was severe LVSD (2.9 % vs. 0.3% P = 0.016). Age, smoking, renal impairment ,and CCS > 216 were independent predictors of mortality.

CONCLUSIONS

Patients with raised CCS on SPECT-MPI have increased mortality and poor LV function despite a negative MPI.

Improved compliance with reporting standards: A retrospective analysis of Intersocietal Accreditation Commission Nuclear Cardiology Laboratories

BACKGROUND

In 2011, Tilkemeier et al reported significant nuclear cardiology laboratory noncompliance with reporting standards. The aim of this study was to identify and examine noncompliant reporting elements with the Intersocietal Accreditation Commission Nuclear/PET (IAC) Reporting Standards and to compare compliance between 2008 and 2014.

METHODS

This was a retrospective study of compliance with 18 reporting elements utilizing accreditation findings from all laboratories applying for accreditation in 2008 and 2014.

RESULTS

1816 labs applying for initial or subsequent accreditation were analyzed for compliance. The mean reporting noncompliance per lab decreased from 2008 to 2014 (2.48 ± 2.67 to 1.24 ± 1.79, P < .001). Noncompliance decreased across lab types, labs with Certification Board of Nuclear Cardiology physicians on staff, and by geographic region (P < .001). Overall severity of reporting issues decreased. Facilities with compliant reports increased from 35.0% in 2008 to 57.1% in 2014 (P < .001).

CONCLUSION

Continuing medical education, accreditation, and other instructional activities aimed at improving nuclear cardiology reporting appear to have made a positive impact over time with the number and severity of noncompliance decreased. More labs are now compliant with the IAC Standards and, thus, reporting guidelines. However, the need for continued educational efforts remains.

Can administration of metoclopramide reduce artefacts related to abdominal activity in myocardial perfusion SPECT?

OBJECTIVES

Myocardial perfusion SPECT is frequently affected by artefacts related to abdominal activity. Metoclopramide has been suggested to relieve this, but two previous studies have shown conflicting results.

METHODS

Ninety-five patients received 10 mg metoclopramide orally after injection of 99mTc-tetrofosmin for the stress scan and 86 patients had metoclopramide after their rest injection. A control group of 82 patients did not receive metoclopramide. Scans were evaluated visually by three readers.

RESULTS

Metoclopramide given before the stress scan led to abdominal activity being visually better in 16 scans, worse in 10, and unchanged in 67 scans, compared to the same patient's rest scan without metoclopramide administration. Metoclopramide administered before the rest scan resulted in abdominal activity in 11 scans being visually better, in 19 worse, and 53 scans were deemed unchanged. These differences were not significant. The number of repeat stress or rest scans was not significantly different between patients who had received metoclopramide and those who had not. The administration of metoclopramide, irrespective of whether it was given before the stress or rest scan, made no significant difference to inferior wall-to-abdomen count ratio.

CONCLUSION

Neither qualitative nor quantitative analysis showed an effect of metoclopramide on abdominal activity in myocardial perfusion SPECT.

X-ray-based attenuation correction of myocardial perfusion scans: practical feasibility and diagnostic impact

OBJECTIVES

This study describes the practical implementation of X-ray-based attenuation correction (AC) of myocardial perfusion scans in a large teaching hospital, characterizes the impact of AC on the diagnostic confidence of the interpreter and tries to predict which patients are likely to benefit from the technique.

METHODS

One hundred and seven consecutive patients underwent a 2 day (99m)Tc-tetrofosmin protocol with adenosine stress using GE Millennium VG with AC and ECG-gated acquisition (ECG-g). The diagnostic impact of AC/ECG-g was judged by a panel of three observers.

RESULTS

AC was not achieved in 46 patients. Individual observers rated AC 'essential' in 37 scans and 'helpful' in 68 scans. For ECG-g, this applied to 12 and 78 scans, respectively. The rating for AC was better than that for ECG-g in 57 scans, and vice versa in 31 scans. Equal ratings were recorded in 41 scans, and neither technique was needed in 54 scans. Diagnostic interpretation of abnormal scans was significantly more likely to benefit from either AC or ECG-g than interpretation of normal scans. Patients in whom AC was considered useful had a significantly higher body mass and chest circumference, but the overlap was large.

CONCLUSIONS

In practice, AC was not feasible in a significant proportion of our patients. AC received better ratings from observers more often than ECG-g. Interpreter confidence with AC was significantly greater in scans with perfusion defects than in normal scans. Body mass and chest circumference cannot be used to predict which patients will benefit from AC.

Efficacy of milk versus water to reduce interfering infra-cardiac activity in 99mTc-sestamibi myocardial perfusion scintigraphy

OBJECTIVE

Interference from infra-cardiac radionuclide activity prevents accurate interpretation of true myocardial perfusion. The study aim was to compare the efficacy of milk versus water in reducing infra-cardiac activity in myocardial perfusion scintigraphy.

METHODS

We prospectively randomized 198 patients undergoing stress-rest (99m)Tc-sestamibi SPECT with exercise or pharmacological stress to drink 300 ml of water or milk prior to imaging. A semi-quantitative grading of the relative intensity of infra-cardiac activity compared to the myocardial activity and a qualitative assessment of the effect on the overall interpretation was performed.

RESULTS

For stress images, there was no infra-cardiac activity in 37.9%, less intense infra-cardiac activity in 40.8%, equal in 11.7% and greater than infra-cardiac activity in 9.7% with milk, compared with 20.0%, 49.5%, 20.0% and 10.5%, respectively, with water (P=0.038). For rest images, there was also less intense infra-cardiac activity with milk compared to water (P=0.014). However, no change in subsequent image interpretation was seen.

CONCLUSION

Administration of milk resulted in a significant decrease in the intensity of infra-cardiac activity compared to water. However, this did not translate into an improvement in image interpretation.

Myocardial perfusion imaging and cardiac events in a cohort of asymptomatic patients with diabetes living in southern France

AIMS

To assess the association between abnormal stress myocardial perfusion imaging (MPI) and cardiac events (CE) in asymptomatic patients with diabetes and with > or = 1 additional risk factor. Predictors of abnormal stress MPI were also evaluated.

METHODS

Four hundred and forty-seven consecutive patients who underwent stress MPI were prospectively followed for 2.1 [0.5-4.1] years for the subsequent occurrence of hard CE (myocardial infarction and sudden or coronary death) and soft CE (unstable angina and ischaemic heart failure requiring hospitalization). Re-vascularization procedures performed as a result of the screening protocol were not included in the analysis.

RESULTS

Follow-up was successful in 419 of 447 patients (94%), of whom 71 had abnormal MPI at baseline. Medical therapy was intensified in all subjects and especially in those with abnormal MPI. Twenty-three patients with abnormal MPI underwent a re-vascularization procedure. CEs occurred in 14 patients, including six of 71 patients (8.5%) with abnormal MPI and eight of 348 patients (2.3%) with normal MPI (P < 0.005). Only two patients developed a hard CE and 12 a soft CE. In multivariate analysis, abnormal MPI was the strongest predictor for CEs [odds ratio (OR) (95% CI) = 5.6 (1.7-18.5)]. Low-density lipoprotein cholesterol > or = 3.35 mmol/l [OR (95% CI) = 7.3; 1.5-34.7] and age > median [OR (95% CI) = 6.0 (1.2-28.6)] were additional independent predictors for CE. The independent predictors for abnormal MPI were male gender, plasma triglycerides > or = 1.70 mmol/l, creatinine clearance < 60 ml/min and HbA1c > 8%, with male gender the strongest [OR (95% CI) = 4.0 (1.8-8.8)].

CONCLUSIONS

Asymptomatic patients with diabetes in this study had a very low hard cardiac event rate over an intermediate period. This could be explained by the effects of intervention or by the low event rate in the background population. Randomized studies of cardiac heart disease screening are required in asymptomatic subjects with diabetes to determine the effectiveness of this intervention.

UK nuclear medicine survey 2003-2004

OBJECTIVES

This survey was designed to assess the trends in the frequencies of nuclear medicine procedures in the UK and to determine their contributions to the annual collective effective dose to the UK population. The average activities administered by nuclear medicine departments were compared with guidance on diagnostic reference levels issued by the Administration of Radioactive Substances Advisory Committee.

METHOD

The survey was carried out by e-mailing a questionnaire to every known nuclear medicine centre in the UK.

RESULTS

The total number of procedures performed annually has increased by 36% over the last 10 years to a level of about 11 procedures per 1000 head of population in the financial year 2003-2004. Seventy-three per cent of all nuclear medicine administrations are for planar imaging, with single-photon emission computed tomography and positron emission tomography contributing 16% and 2%, respectively. Non-imaging diagnostic procedures represent 7% of all nuclear medicine administrations, and therapy 2%. Bone scans continue to be the most frequent procedure. The UK annual collective effective dose from diagnostic nuclear medicine is about 1600 man Sv, resulting in an annual per caput dose of nearly 0.03 mSv. Bone scans are the largest contributor to the collective dose, but myocardium scans are close behind. Planar imaging is responsible for 62% of the total collective effective dose from diagnostic nuclear medicine in the UK, with single-photon emission computed tomography, positron emission tomography and non-imaging contributing 33%, 5% and 0.3%, respectively.

CONCLUSIONS

The practice of nuclear medicine is still expanding in the UK with single-photon emission computed tomography imaging of the myocardium rapidly approaching bone scans as the main contributor to population exposure. The activities administered for most procedures have remained substantially unchanged and adhere closely to those recommended by the Administration of Radioactive Substances Advisory Committee.

The effect of Butterworth and Metz reconstruction filters on volume and ejection fraction calculations with 99Tcm gated myocardial SPECT

This study was carried out to measure the differences produced by change of reconstruction filter in calculations of left-ventricular end-diastolic volumes, end-systolic volumes, stroke-volumes and left-ventricular ejection-fractions from (99)Tc(m) Sestamibi (Bristol-Myers Squibb) gated myocardial perfusion SPECT studies. 30 patients had gated SPECT myocardial perfusion imaging at rest. The acquired projections were separately filtered with two filters, a low-pass filter (Butterworth) and an edge-enhancement filter (Metz). Each study was then further processed to determine left-ventricular end-diastolic volume, end-systolic volume, stroke volume and ejection fraction, and to assess defect size. The results for each patient with the two filters were compared. Calculated end-diastolic volumes, end-systolic volumes and left-ventricular ejection fractions, for each filter, were well correlated. Stroke volumes showed worse correlation. The differences between left-ventricular ejection-fractions, end-diastolic volumes and end-systolic volumes were statistically significant. There was no significant difference in stroke volumes. Ejection fractions were inversely correlated with defect size, but change in ejection fraction due to filter was not. End-diastolic and end-systolic volumes were correlated with defect size, but change in volumes due to filter was not. Thus the results for changes produced by choice of filter are not dependent on defect size. Using different reconstruction pre-filters in gated myocardial perfusion SPECT significantly changes the results of calculations of physiological parameters. Each centre should be consistent in the use of filters as this may affect the clinical consequences of the result.

Are exercise stress tests appropriate for assessing myocardial ischemia in patients with major depressive disorder?

BACKGROUND

Major depressive disorder (MDD) disproportionately affects patients with coronary artery disease (CAD). Evidence of myocardial ischemia with electrocardiography (ECG) or single-photon-emission-computed-tomography (SPECT) assessments during exercise testing is an important determinant of CAD prognosis. However, many key symptoms of MDD, such as reduced interest in daily activities, lack of energy, and fatigue, may affect exercise performance and the detection of ischemia in patients with MDD. This study evaluated the extent to which MDD and depressive symptomatology moderate exercise test performance and compared the ability of ECG versus SPECT for detecting ischemia in 1367 consecutive patients who underwent exercise testing.

METHODS

All patients underwent a brief, structured psychiatric interview (PRIME-MD) and completed the Beck Depression Inventory (BDI) on the day of their exercise (treadmill) test.

RESULTS

A total of 183 patients (13%) met diagnostic criteria for MDD. Patients with MDD achieved a significantly lower percent of maximal predicted heart rate (%MPHR), exhibited lower peak exercise mets, and spent less time exercising compared with patients without MDD (all P values <.05). BDI scores were also negatively correlated with all 3 indices of exercise performance (all P values <.01). There were no differences in rates of SPECT ischemia in patients with MDD (40%) versus patients without MDD (45%; P =.23); however, rates of ECG ischemia were significantly lower (30%) in patients with MDD than in patients without MDD (48%; P <.0001).

CONCLUSIONS

Results suggest that patients with CAD who have MDD, depressive symptomatology, or both exhibit poor exercise tolerance and performance and that ECG, as compared with SPECT, may not be as reliable in detecting ischemia in patients who are depressed.