[Myocardial perfusion scintigraphy - short form of the German guideline]

Myocardial scintigraphy - a method for detecting cardiac comorbidity in psoriasis patients?

BACKGROUND

In recent years, cardiac comorbidities in psoriasis patients have increasingly moved into the focus of clinical research. The objective of the present study was to evaluate myocardial scintigraphy as a screening method in patients with psoriasis.

PATIENTS AND METHODS

Assessment of various comorbidities in 50 psoriasis patients without clinical symptoms of cardiac disease. Myocardial scintigraphy was employed to detect cardiac risk/exercise-induced ischemia.

RESULTS

Twenty-eight patients (56 %) had pathological findings on myocardial scintigraphy. Fourteen individuals showed evidence of small-vessel disease (cardiac syndrome X). Other comorbidities included obesity, arterial hypertension, nicotine and alcohol abuse, as well as elevated CRP levels. Frequencies largely corresponded to those reported in the recent literature. There was no significant correlation between the severity of psoriasis or any comorbidities and pathological findings on myocardial scintigraphy.

CONCLUSIONS

Myocardial scintigraphy seems to be a very sensitive, noninvasive method for the early detection of cardiac comorbidities in psoriasis patients. However, determining its true diagnostic value will require larger studies with control subjects and control methods such as coronary angiography.

The effect of beta blocker withdrawal on myocardial SPECT modeled from adenosine 13N-ammonia PET

AIM

The effect of beta blockers (BB) on myocardial imaging has been studied in several SPECT and PET studies with divergent results concerning perfusion and impact on diagnostic accuracy. The present study evaluated the effect of BB withdrawal on virtual SPECT studies modeled from quantitative PET perfusion scans.

PATIENTS, METHODS

Data from 20 CAD patients scheduled for adenosine 13N-ammonia imaging with and without BB were considered. Modeling the uptake characteristics of 99mTc-MIBI, all parametric stress PET polarmaps were transferred to virtual 20-segment SPECT polarmaps. The SPECT studies were categorized with a 5-point score and read to assess the effect of the BB withdrawal on scan result and interpretation.

RESULTS

The SPECT analysis revealed a mean score of 6.0 ± 4.7 with, and of 5.9 ± 4.5 without BB (p = 0.84). In 260 (74.9%) segments the scores were equal in both conditions. Without BB a downstaging was recorded in 44 segments (12.7%), an upstaging in 43 segments (12.4%). An essentially different interpretation (shift from medical therapy recommendation to angiography) was recorded in one patient. In six cases the interpretation differed mildly.

CONCLUSION

In the majority of patients studied, scan results and interpretation remain unchanged after discontinuation of the BB. Nevertheless, the segmental scan results are not uniformly affected. The recommendation to stop BBs prior to stress testing in order to ensure the highest MBF remains advisable. If temporary BB withdrawal is unfeasible due to contraindications, a tight clinical schedule, or because a patient forgot to withhold the BB, it is appropriate to perform adenosine stress testing according to the results of this study.

99mTc tetrofosmin myocardial perfusion scintigraphy in CAD. Performance with early and standard delayed acquisition and fractional flow reserve

AIM

Early stress imaging (15 min after injection of the radiopharmaceutical) in 99mTc tetrofosmin myocardial perfusion scintigraphy (MPS) has been shown feasible in comparison to standard imaging after 45 minutes, but the effects on image quality and diagnostic accuracy ask for further evaluation.

PATIENTS, METHODS

97 patients (61 men, 36 women, age 69 ± 11 years) underwent both early (EA) and standard (SA) acquisition (after 14 ± 4 min and 43 ± 6 min, respectively) using 99mTc tetrofosmin gated SPECT with iterative reconstruction. Sub-diaphragmatic tracer activity and image quality was scored in a 4-point scale by blinded observers. Semiquantitative myocardial perfusion analysis was performed on a 17-segment model using standard cardiac quantification SPECT software (4 DM-SPECT). Stenoses of indeterminate haemodynamic significance were validated by measurement of fractional flow reserve (FFR).

RESULTS

Extra-cardiac tracer activity was more commonly found in EA (43%) than in SA (38%), but without any diagnostic impact in > 95% of the patients. The mean summed stress score was significantly higher for early than standard imaging (6.4 ± 6.3 vs. 5.6 ± 6.1, p = 0.009). The amount of ischaemic area was not significantly different (EA: 9.1 ± 6.7 % vs. SA: 7.8 ± 6.9 %). The mean stress ejection fraction was 52 ± 11% (EA) compared to 55 ± 11 % (SA) (p = ns). FFR was inversely related to SDS at early (r = -0.704, p < 0.05) and standard (r = -0.678, p < 0.05) acquisition. All patients with a FFR < 0.8 (considered as hemodynamically significant stenoses) revealed a positive scan.

CONCLUSION

Stress 99mTc tetrofosmin MPS with early acquisition is feasible and at least equally accurate when iterative reconstruction is applied.

Use of myocardial perfusion imaging and estimation of associated radiation doses in Germany from 2005 to 2012

PURPOSE

For several years the Working Group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine has been performing a regular survey to obtain information on technique, utilization and development of myocardial perfusion scintigraphy (MPS). Currently, data of six surveys from 2005 to 2012 are available. The aim of this paper is to deliver a general and comprehensive overview of all surveys documenting the course of patient doses over time and the development of the method.

METHODS

A one-page questionnaire with number of MPS patients, number of stress and rest MPS, referral structure and several technical issues was sent to all centres performing MPS in Germany and evaluated. With the data on protocol utilization, effective MPS patient doses were estimated.

RESULTS

MPS per million population (pmp) varied between 2,380 and 2,770. In 2012, MPS pmp showed a slight increase for the first time. From 2005 to 2009 the angiography to MPS ratio increased from 3.4 to 4.4, and the revascularization to MPS ratio decreased from 0.66 to 0.53. In 2012, both indices demonstrated an opposite trend for the first time (4.1 and 0.55). A total of 108 centres participated in all surveys. They showed an increase in MPS patients of 4.0 % over the reporting period. In 2012, more than 50 % of the centres experienced no change or an increase in MPS numbers. The leading single competitor was MRI, followed by angiography and stress echocardiography. (201)Tl studies have decreased since 2005 from 20 to 5 %. (99m)Tc MPS studies showed a mild increase in 2-day protocols. In 2012, the average effective dose per patient was estimated at 7.4 mSv. Due to the decreasing use of (201)Tl, a mild decline over the observation period can be documented. Dynamic exercise stress was the most common stress test and adenosine the leading pharmacological stress agent, with a growing percentage. In 2012, the regadenoson percentage was 9 %. Gated single photon emission computed tomography (SPECT) noted an increasing acceptance with >70 % in 2012. The segmental scoring of perfusion studies had a low acceptance. Ambulatory care cardiologists represented the major referral group.

CONCLUSION

Germany has a moderate to moderate-high MPS utilization rate. Nevertheless, coronary artery disease (CAD) diagnosis and disease management are dominated by angiography. The survey data reveal a positive trend in MPS and a decrease in average patient dose reflecting good practice with guideline adherence, the implementation of technical improvements and success in training.

[Myocardial perfusion scintigraphy 2012 in Germany. Results of the 6th Query]

AIM

The working group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine presents the results of the 6th survey on myocardial perfusion scintigraphy (MPS) of the reporting year 2012.

METHOD

278 questionnaires (177 private practices (PP), 78 hospitals (HO), 23 university hospitals (UH)) were evaluated.

RESULTS

MPS of 105,941 patients were reported. 95% [2005 = 80%] of MPS studies were conducted with (99m)Tc perfusion radiopharmaceuticals and only 5% with 201Tl. 79% [2009 = 76%] of the MPS were performed in PP, 15% [2009 = 17%] in HO, and 6% [2009 = 7%] in UH. Data from 108 centres which participated in all surveys from 2005 to 2012 showed an increase in MPS numbers of 4.0% (PP +6.1%, HO +18.2%, UH -18.3%). 29% of all participants (27% of PP, 31% of HO, and 26% of UH) noticed no change and 26% of all participants (28% of PP, 17% of HO and 35% of UH) an increase in their MPS requests since the 2009 query. The type of stress was pharmacological in 39% [2009 = 31%]. Of these 61% with adenosine (39% with exercise), 22% with regadenoson (51% with exercise), 14% with dipyridamole (60% with exercise), and 3% with dobutamine. Gated SPECT was performed in 73% [2009 = 56%] of all rest, in 70% [2009 = 56%] of all stress and in 67% [47%] of all stress and rest MPS. Only 36% [2009 = 33%] of the centres performed a quantification of all their studies with scores, whereas 41% [2009 = 52%] did not apply any quantification. 60% [2009 = 49%] of the MPS were requested by ambulatory care cardiologists.

CONCLUSION

The survey on MPS in Germany reveals a good conformity of imaging procedures with the current guideline. A positive development in MPS practice and referral can be stated. However, there is still some potential of MPS processing considering the quantitative perfusion analysis.