Anna Płachcińska

Routine quality control recommendations for nuclear medicine instrumentation

Keywords Qualitycontrol.Qualityassurance.Nuclearmedicineinstrumentation.Gammacamera.SPECT.PET.CT.Radionuclidecalibrator.Thyroiduptakeprobe.Nonimagingintraoperativeprobe.Gammacountingsystem.Radiationmonitors.PreclinicalPETIntroductionThese recommendations cover routine quality control (QC)of instrumentation used within a nuclear medicine depart-ment. Routine QC testing starts after installation of theinstrument, and after acceptance testing, and continues on aregular basis throughout its lifetime. Additional periodictests may be carried out to provide more in-depth testing.Recommendations for acceptance testing are covered in aseparate document. These recommendations must be con-sideredinthelightofanynationalguidelinesandlegislation,which must be followed. The recommendations cover thetypes of tests to be performed, and suggested frequencies,but they do not specify the protocols to be followed, whichare available from other reference sources quoted.Acceptance and reference testsAfter installation, and before it is put into clinical use, anuclear medicine instrument must undergo thorough andcareful acceptance testing, the aim being to verify that theinstrument performs according to its specifications and itsclinical purpose. Each instrument is supplied with a set ofbasic specifications. These have been produced by themanufacturer according to standard test procedures, whichshould be traceable to standard protocols, such as theNEMA and IEC performance standards [1–4, 11, 17, 30,37]. By following such standard protocols in the clinicalsetting, with support from the vendor for supplyingphantoms and software where necessary, specificationscan be verified and baseline performance data created.Additional tests are usually also needed in order to more

Accelerated Stress Real-Time Myocardial Contrast Echocardiography for the Detection of Coronary Artery Disease: Comparison with 99mTc Single Photon Emission Computed Tomography

OBJECTIVE The aims of this prospective study were to compare the diagnostic value of accelerated vasodilator stress real-time myocardial contrast echocardiography (MCE) and single photon emission computed tomography (SPECT) against coronary angiography and to evaluate whether the addition of MCE perfusion data improves the diagnostic accuracy of stress echocardiography. METHODS A total of 103 patients with suspected or known stable coronary artery disease (CAD) underwent SPECT and accelerated high-dose dipyridamole (0.84 mg/kg intravenously for 4 minutes) atropine (up to 1 mg intravenously) stress real-time qualitative MCE. The presence of CAD was detected by coronary angiography. RESULTS CAD defined as >or= 70% stenosis was detected in 77% of patients, whereas 86% of patients had CAD defined as >or= 50% stenosis. In a territory-by-territory analysis, the concordance between MCE and SPECT in detecting perfusion defects varied from 72.8% (kappa = 0.386) to 89.3% (kappa = 0.642). There were no significant differences between MCE and SPECT in sensitivity, specificity, and diagnostic accuracy for identifying patients with CAD. Combining MCE and wall motion abnormality analysis significantly improved the sensitivity of the test compared with wall motion abnormality analysis alone. CONCLUSIONS Accelerated vasodilator stress real-time MCE yields a good concordance with SPECT in detection of perfusion defects and a similar diagnostic value for the detection of CAD. The addition of MCE perfusion data improves the diagnostic value of stress echocardiography.

Acceptance testing for nuclear medicine instrumentation

These recommendations cover acceptance and reference tests that should be performed for acceptance testing of instrumentation used within a nuclear medicine department. These tests must be performed after installation and before the instrument is put into clinical use, and before final payment for the device. These recommendations must be considered in the light of any national guidelines and legislation, which must be followed. The recommendations cover the types of test to be performed, but they do not specify the procedures to be followed, which are available from other reference sources quoted. Acceptance testing is extremely important, as it can affect the whole life performance of a system. The requirement that acceptance testing be performed should be included in the purchase agreement of an instrument. This agreement should specify responsibilities regarding who does acceptance testing, the procedure to be followed when unsatisfactory results are obtained, and who supplies the required phantoms and software. A specific time slot must be allocated for performing acceptance tests.

Clinical Usefulness of 99mTc-EDDA/HYNIC-TOC Scintigraphy in Oncological Diagnostics: A Pilot Study

The clinical usefulness of a new 99mTc-labeled somatostatin analogue has been studied from the standpoint of oncological diagnostics. The group of patients studied included 40 individuals with diagnosed malignant neoplasms (32 primary and 8 metastatic). Among the primary tumors were 7 pituitary adenomas (5 hormonally active and 2 inactive), 1 liposarcoma, 2 carcinoids, 1 breast carcinoma, and 21 cases of lung cancer (2 small cell and 19 non-small cell) were represented. The metastatic tumors consisted of: 3 malignant melanomas, 1 pheochromocytoma, 1 prostatic cancer, 1 leiomyosarcoma, 1 pancreatic carcinoma ectopically secreting ACTH, and 1 carcinoid of the thymus. The radiopharmaceutical, 99mTc-EDDA/HYNIC-octreotide, was i.v. administered at the activity of 740-925 MBq. The imaging was comprized of a whole-body scan and single photon emission computed tomography. Positive scintigrams were obtained in 4 of 5 hormonally active pituitary adenomas, in 1 of 2 cases of carcinoid, in liposarcoma, breast cancer, and all cases of small cell (SCLC) and non-small cell lung cancer (NSCLC). The neoplastic metastases were visualized in 2 of 3 cases of melanoma and in patients with pheochromocytoma, pancreatic carcinoma secreting ACTH, and thymic carcinoid. Scintigrams were negative in both hormonally inactive pituitary adenomas, in one case of metastatic malignant melanoma, leiomyosarcoma, and in cases of metastasis from the prostatic carcinomas. The results of this pilot study indicated that 99mTc-EDDA/HYNIC-TOC is a potentially useful radiopharmaceutical for the imaging of a wide range of primary and metastatic tumors. More detailed indications for the clinical usefulness of the new tracer for the imaging of selected tumor types require studies on much larger groups of patients. Special attention should be paid to the successful imaging of all cases of NSCLC.

Gated 99mTc-MIBI single-photon emission computed tomography for the evaluation of left ventricular ejection fraction: comparison with three-dimensional echocardiography

ObjectiveParameters of left ventricular systolic function directly influence the management of patients with suspected coronary artery disease (CAD). Quantitative gated single-photon emission computed tomography (QGS; Cedars-Sinai Medical Center, Los Angeles, CA, USA) allows the computation of left ventricular ejection fraction (LVEF) from myocardial perfusion imaging studies which are frequently performed on patients with suspected CAD. Three-dimensional (3D) echocardiography is considered to be the echocardiographic “gold standard” for the quantification of LVEF. We sought to compare QGS with 3D echocardiography in the evaluation of EF in patients with suspected CAD.MethodsNinety-one consecutive patients with suspected CAD, scheduled for coronary angiography, underwent rest electrocardiographic-gated technetium-99m methoxyisobutylisonitrile SPECT (G-SPECT) with measurement of LVEF by QGS and transthoracic 3D echocardiography with off-line measurement of LVEF (Tomtec 4D LV Analysis 1.1). The diagnosis of CAD was based on coronary angiography, performed on every patient.ResultsNine patients were excluded from the analysis owing to unsuitability for 3D echocardiography (8 patients) or G-SPECT (1 patient). In the remaining group of 82 patients, 71 (87%) had significant CAD, 34 (42%) had a history of myocardial infarction, and 50 (61%) had perfusion defects at rest G-SPECT images. The mean LVEF measured by QGS and 3D echocardiography was 53 ± 13% and 53 ± 10%, respectively. The mean difference in LVEF between 3D echocardiography and QGS was 0.1 ± 6.0% (P = 0.87), and the correlation between the values obtained by both methods was high (r = 0.88, P < 0.001). The largest discrepancies were observed in patients with small ventricular volumes.ConclusionsIn patients undergoing diagnostic work-up for CAD, the measurement of LVEF by QGS algorithm provides high correlation and satisfactory agreement with the results of reference ultrasound method-3D echocardiography.

Quantitative assessment of technetium-99m methoxyisobutylisonitrile planar perfusion heart studies: application. of multivariate analysis to patient classification

A quantified evaluation of planar cardiac perfusion scintigrams (the objective of the study), obtained using technetium-99m methoxyisobutylisonitrile (MIBI) was performed on the basis of an analysis of circumferential profile curves, representing the perfusion as seen in three typical projections. The analysis involved the curves obtained both at rest and after stress, and was based on a comparison of their shape (trend) with the normal trend (normative evaluation). The latter was obtained by means of an original method of iterative fitting of individual curves into the database. The base consisted of curves recorded in 53 patients (separately in males and females) with normal perfusion of the left ventricle (group I, the reference group). A group of 90 patients suspected of having coronary artery disease (group II) was subdivided into two subgroups on the basis of coronary arteriography: (a) those with and (b) those without critical stenosis of at least one artery. Profile curves characterising the LV perfusion were obtained at rest and after stress. Defects of perfusion were quantified by comparison of individual curves with the normal trends. By means of multivariate analysis it was demonstrated that vectors of mean values characterising the scintigraphically assessed defects of LV perfusion in the two subgroups of group II differed very significantly (P<10−5). Applying methods of discriminant analysis, a classification of patients from group II was performed into those with probable defects of perfusion and those free of such defects. The sensitivity, specificity and accuracy of diagnosis of coronary ischaemia, based on quantified planar99mTc-MIBI scintigraphy, reached 86%, 87% and 87%, respectively.

Perfusion lung scintigraphy for the prediction of postoperative residual pulmonary function in patients with lung cancer

BACKGROUND Accurate prediction of postoperative pulmonary function in patients with non-small cell lung cancer is crucial for proper qualification for surgery, the only effective therapeutic method. The aim of the study was to select the most accurate method for acquisition and processing of lung perfusion scintigraphy (LPS) combined with spirometry for prediction of postoperative pulmonary function in patients qualified for surgery. MATERIAL AND METHODS LPS was performed in 70 patients (40 males, 30 females), with preoperative spirometry (mean FEV1preop = 2.26 ± 0.72 L), after administration of 185 MBq of 99mTc-microalbumin/macroaggregate, using planar (appa) and SPECT/CT methods. Predicted postoperative lung function (FEV1pred) was calculated as a part of active lung parenchyma to remain after surgery. A non-imaging segment counting method was also applied. FEV1pred(appa, SPECT, SPECT/CT, segm.) were further compared with actual FEV1postop values obtained from postoperative spirometry. RESULTS In the whole studied group (47 lobectomies, 23 pneumonectomies) mean value of FEV1postop was equal to 1.76 (± 0.56) L. FEV1pred(appa, SPECT, SPECT/CT, segm.) were equal to 1.75 (± 0.58) L, 1.71 (± 0.57) L, 1.72 (± 0.57) L and 1.57 (± 0.58) L, respectively. A segment counting method systematically lowered predicted FEV1 values (p < 10-5). Moreover, in 31 patients with FEV1preop < 2 L error of predicted values was assessed with Bland-Altman method. Mean absolute differences FEV1postop - FEV1pred amounted to: appa - (0.04 ± 0.13) L, SPECT - (0.07 ± 0.14) L, SPECT/CT - (0.06 ± 0.14) L and segm. - (0.21 ± 0.19) L, respectively. Lower limit of 95% confidence interval calculated for planar - optimal method, was equal to -220 mL (also determined separately in subgroups after lobectomy and pneumonectomy). CONCLUSIONS This study shows that planar LPS may be applied for prediction of postoperative pulmonary function in patients qualified for pneumonectomy and lobectomy. If actual FEV1postop value is to be ≥ 800 mL, predicted value should exceed 1000 mL.

Long-term prognostic value of inducible and resting perfusion defects detected by single-photon emission computed tomography in the era of wide availability of coronary revascularization.

To assess the long‐term prognostic value of various types of perfusion defects detected by single‐photon emission computed tomography (SPECT) in patients with stable angina.

Patient exposure to ionising radiation due to nuclear medicine cardiac procedures

Nuclear cardiology procedures are among the most extensively performed radionuclide studies. Procedures for the assessment of myocardial perfusion, contractile function and metabolism have gained a prominent position in clinical practice. Health risk to patients from radiopharmaceuticals results only from exposure to ionizing radiation. Nuclear medicine diagnostic procedures,including the cardiological ones, are accompanied by a very small risk of radiation induced malignant tumours. Death risk from stress and rest perfusion of myocardium (effective dose of about 10 mSv) could be estimated as lower than 0.1 per mille.

Diagnostic value of optimised real-time sonoelastography in the assessment of liver fibrosis in chronic hepatitis B and C

Aim To optimise the method of real-time elastography (RTE) in the assessment of liver fibrosis using an in-house prepared method for elastogram analysis, as well as a semiquantitative analysis based on newly introduced parameters. Material and methods Sonoelastography was performed in 94 patients with various degrees of liver fibrosis and also in 25 healthy volunteers. As a reference method for diagnostic efficacy of sonoelastography-based parameters used for the assessment of fibrosis degree in patients with chronic B and C hepatitis, a liver biopsy was used. Patient’s elastograms were analysed using in-house prepared software, Pixel Count, calculating two semiquantitative parameters: mean stiffness fraction (MSF%) and intrinsic stiffness ratio (ISR). Results Statistically significant differences between distributions of the above presented parameters for different degrees of liver fibrosis were revealed. Indices of diagnostic efficacy for detection of significant liver fibrosis (F ≥ 2) using MSF% amounted to: sensitivity – 76%, specificity – 87% and ISR: 81% and 87%, respectively. Sensitivity of both parameters in detection of cirrhosis (F = 4) was equal to 88% and specificity amounted to: for MSF% – 84% and ISR – 86%. Interobserver reproducibility determined for both of the above parameters was high, intraclass correlation coefficients (ICC) were 0.91 for MSF% and 0.93 for ISR. Conclusions Real-time elastography applied in this study, using in-house prepared Pixel Count software, provided good reproducibility and diagnostic efficacy, especially specificity, in the assessment of liver fibrosis degree.