Ellinor Busemann Sokole

EANM/ESC procedural guidelines for myocardial perfusion imaging in nuclear cardiology

The European procedural guidelines for radionuclide imaging of myocardial perfusion and viability are presented in 13 sections covering patient information, radiopharmaceuticals, injected activities and dosimetry, stress tests, imaging protocols and acquisition, quality control and reconstruction methods, gated studies and attenuation-scatter compensation, data analysis, reports and image display, and positron emission tomography. If the specific recommendations given could not be based on evidence from original, scientific studies, we tried to express this state-of-art. The guidelines are designed to assist in the practice of performing, interpreting and reporting myocardial perfusion SPET. The guidelines do not discuss clinical indications, benefits or drawbacks of radionuclide myocardial imaging compared to non-nuclear techniques, nor do they cover cost benefit or cost effectiveness.

Value and limitations of thallium-201 scintigraphy in the acute phase of myocardial infarction

We examined the diagnostic usefulness of thallium-201 scintigraphy in 200 patients with acute myocardial infarction. The scintiscans showed a defect, suggesting infarction in 165. In all 44 patients studied iwthin six hours after onset of symptoms the scintiscans indicated a defect. Frequency of positive scans was significantly higher (90 of 96) in patients studied within 24 hours after onset than in those (75 of 104) studied later (p less than 0.01).

Location and size of acute transmural myocardial infarction estimated from thallium-201 scintiscans. A clinicopathological study.

A clinicopathological study was performed in 23 patients who died from acute transmural myocardial infarction and who had been studied with thallium-201 during the acute phase. Twenty patients died within five days and three later than five days after scintigraphy. The scintigraphic location and the estimated size of infarction in vivo were correlated with postmortem findings. There was good agreement in 91%percnt; between scintigraphic and postmortem location of infarction and in 70%percnt; between the ECG and postmortem find- ings. The size of infarction as determined from computer-processed schematic drawings of postmortem slices of the heart correlated well with the size determined from processed schematic drawings of the scintiscans (r = 0.91 for anterior infarction, r = 0.97 for inferior infarction, r = 0.86 for anterior-inferior infarction). It is concluded that thallium-201 scintigraphy provided more precise location of infarction than the ECG and that the size of the scintigraphically abnormal area reflected the extent of necrotic myocardium.

Thallium-201 scintigraphy in unstable angina pectoris.

SUMMARYThallium-201 scintigraphy was performed during the pain free period in 98 patients with unstable angina. Scintiscans were positive in 39 patients, questionable in 27 patients and normal in 32 patients. Eighty-one patients responded favorably to treatment (group I). Seventeen patients had complicated courses (group Il) and despite maximal treatment with propranolol either developed infarction (six patients) or continued to have angina necessitating coronary surgery (11 patients). In group I during the pain free period 26 of 81 patients had positive thallium-201 scans, whereas 20 patients had an abnormal ECG at that time; during angina 18 patients had transient ECG changes. In group II during the pain free period 13 of 17 patients had positive scans, whereas two patients had abnormal ECG at that time; during angina 12 patients showed transient ECG changes. The sensitivity to recognize group 11 was 76% for thallium- 201 scintigraphy, 11% for ECG during the pain free period; 70% for ECG during angina; 94% for the combination of either positive scans or abnormal ECG. Thus, 1) positive thallium-201 scans occur in patients with unstable angina, 2) positive scans can be obtained during the pain free period, 3) thallium-201 scans are more frequently positive in patients with complicated course.

Potential value of thallium-201 scintigraphy as a means of selecting patients for the coronary care unit.

The potential value of thallium-201 scintigraphy as a means of selecting patients for appropriate coronary care unit admission was evaluated. Studies were made prospectively on 203 patients with possible acute myocardial infarction but atypical history and non-diagnostic electrocardiogram at a time when the clinical diagnosis was still in doubt. Under conventional circumstances, this particular group of patients will be admitted to the coronary care unit for observation in order to rule out myocardial infarction by further clinical evaluation. Scintigraphy was performed upon arrival in the coronary care unit and within 10 hours after the last episode of chest pain. Of 203 patients, 49 had positive, 47 had questionable, and 107 had normal thallium-201 scintiscans. Serial serum enzyme determinations and further clinical follow-up disclosed acute myocardial infarction in 34 patients: all had abnormal scans. Of47 patients subsequently determined to present with unstable angina, 27 had abnormal scans, ofwhom 7 subsequently developed acute myocardial infarction. Of 24 patients with previous myocardial infarction, 18 patients had abnormal scans. None of either the 25 patients with stable angina or the 73 patients with atypical complaints showed frank perfusion defects, though questionable abnormal scintiscans were obtained in 5 and 12 patients in these groups, respectively. It is concluded that thallium-201 scintigraphy, when performed within a time interval of 10 hours after the last episode ofchest pain, may be ofvalue as a means of selecting those patients requiring further stay in hospital and observation in the coronary care unit.

Noninvasive visualization of acute myocardial infarction in man with thallium-201.

Myocardial imaging using 201Tl was performed in 10 patients with supposedly normal myocardial perfusion and in 11 patients with acute myocardial infarction. In all patients with acute myocardial infarction the scintiscan showed an area with diminished radioactivity at the site corresponding the electrocardiographic localization of the infarction. 210Tl seems to be of diagnostic value for recognizing acute myocardial infarction in the very first hours after its onset and for visualizing infarction in patients in whom pre-existing electrocardiographic abnormalities prevent its diagnosis and/or localization.

Influence of collimator choice and simulated clinical conditions on 123I-MIBG heart/mediastinum ratios: a phantom study.

Purpose123I presents imaging problems owing to high-energy photon emission. We investigated the influence of collimators on 123I-MIBG heart/mediastinum ratios (H/M ratios). Secondly, we assessed the influence on H/M ratios of different activity concentrations, simulating clinical conditions. Thirdly, the value of scatter correction was assessed.MethodsThe AGATE cardiac phantom was filled with 123I in three sequential conditions: A, heart and mediastinal activity; B, adding lung activity; and C, adding liver activity (protocol I). In protocol II, myocardium and liver were filled with different activities ranging from low to high. For each condition, static anterior planar and single-photon emission computed tomography studies were acquired on a Siemens e.cam (SI) and a General Electric Millennium VG (GE) system, using low-energy high-resolution and medium-energy (ME) collimators for protocol I and only ME collimators for protocol II . For the SI camera, a triple energy window (TEW) scatter correction was applied.Results Planar H/M ratios were influenced by scatter and septal penetration from increasing amounts of liver activity. These effects were less pronounced for ME collimators. Although the TEW scatter correction increased ratios overall, TEW correction did not improve the relative differences between the ratios. TEW correction therefore does not add any benefit to obtain an accurate reflection of myocardial activity concentrations.Conclusion For straightforward implementation of semi-quantitative 123I-MIBG myocardial studies, we recommend the use of ME collimators without scatter correction.

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

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.

Dosimetry of iodine-123 iodobenzamide in healthy volunteers

The distribution of the dopamine D2-receptor specific ligand iodine-123 (S)-(−)-2-hydroxy-3-iodo-6-methoxy-N[(1-ethyl-2-pyrrolidinyl)methyl]-benzamide (1231-IBZM) was investigated in human adults from whole-body scans, blood samples and urine collected up to 48 h after injection. Results from the present study performed in six healthy volunteers were combined with those of five volunteers from a previous study. Using the brain, liver, lungs and spleen as source organs, the MIRD method was applied to calculate the absorbed radiation dose of the radioligand in various organs. The thyroid (despite blockage), gall-bladder wall, large intestinal walls and spleen received the highest absorbed doses. The average effective dose equivalent of 123I-IBZM for adults was estimated to be 0.034 mSv/MBq. The absorbed dose to the thyroid may be a limiting factor for 1231-IBZM studies in children.