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Indian Journal of Nuclear Medicine : IJNM : The Official Journal of the Society of Nuclear Medicine, India logoLink to Indian Journal of Nuclear Medicine : IJNM : The Official Journal of the Society of Nuclear Medicine, India
. 2013 Dec;28(Suppl 1):S1–S2.

Nuclear Cardiology

PMCID: PMC3868027
Indian J Nucl Med. 2013 Dec;28(Suppl 1):S1–S2.

Card-01: Single-photon emission computed tomography myocardial perfusion scan: A clinical audit

Mitra Sujata, GS Muthu

Department of Nuclear Medicine and Immunoassay, Tata Main Hospital, Jamshedpur, West Bengal, India

Introduction: SPECT myocardial perfusion scan (MPS) reflects flow heterogeneity and blunted coronary reserve, thus helping in early coronary artery disease (CAD) detection. The ACC/ASNC guidelines summarize the indications of its use in diagnosis and risk stratification in chronic coronary artery disease, acute coronary syndrome and post MI need for intervention.

Objective: The present study was undertaken to audit the usefulness of SPECT MPS in establishing need for intervention (angioplasty/CABG) in CAD.

Materials and Methods: Patients referred for MPS (n = 41) were followed up for type of surgical intervention and outcome. The MPS and CAG findings were compared and concordant as well as discordant reports analyzed, together with treatment outcome. Reversible perfusion defects involving 15% or more of the total myocardial territory was taken as an indication for need for CAG and intervention.

Results: MPS correctly established need for intervention in 26/41 patients who had a perfusion defect of 15% or more of the total myocardial territory. 12 patients had a normal MPS or a perfusion defect less than 15% and they did not require intervention. 3 patients had significant perfusion defect in MPS, but were advised medical management.

Conclusion: Quantitative parameter such as extent of perfusion defect, when added to existing reporting parameters may further help to improve the accuracy of MPS in clinical decision making in CAD patients.

Indian J Nucl Med. 2013 Dec;28(Suppl 1):S1–S2.

Card-02: The association between electrocardiographic changes observed during adenosine stress test and findings of 99mTc-sestamibi gated single-photon emission computed tomography myocardial perfusion scintigraphy

Sameer Kamalakar Taywade, RV Parameswaran

Narayana Hrudayalaya, Bangalore, Karnataka, India

Objective: To evaluate the strength of association between ischemic ECG changes observed during adenosine stress test and findings of 99mTc-sestamibi gated SPECT MPS in the diagnosis of ischemic heart disease.

Materials and Methods: 117 patients with known or suspected coronary artery disease were evaluated with adenosine stress 99mTc-sestamibi myocardial perfusion scintigraphy. During adenosine infusion ST segment depression of 1mm was considered as positive ischemic ECG change. Reversible perfusion defect on MPS was further categorised on the basis of ‘sum difference score’ (SDS), as normal (<4), mild (4-8), moderate (9-13), severe (>13).

Results: Down sloping ST segment depression of ≥1 mm was observed in 27 patients out of total 117 patients (23.1%) during adenosine stress. Among these 27 patients, 18 patients showed myocardial perfusion defect on MPS (66.66%). MPS findings among these 27 patients were as follows: Mild ischemia in 2 patients, moderate ischemia in 6 patients, severe intensity ischemia in 10 patients and normal MPS in 9 patients. There was moderate association between ischemic ECG changes and detection of ischemia on MPS (coefficient of correlation r = 0.35, P = 0.006).

Conclusion: Occurrence of ischemic ECG changes during adenosine stress myocardial perfusion scintigraphy is uncommon. Such ischemic ECG changes usually correspond with moderate to severe perfusion defect on MPS. Occurrence of down sloping ST depression can be considered as specific marker of myocardial ischemia. There is moderate association between this ECG change and reversible perfusion defect on MPS. Therefore, the ECG changes observed during adenosine stress test should be evaluated and carefully correlated with MPS findings.

Indian J Nucl Med. 2013 Dec;28(Suppl 1):S1–S2.

Card-03: Single-shot cardiorenal scintigraphy with Tc-99m MIBI in cardiac patients with or without known renal dysfunction

Biju K Menon, Sushama Awasare, Gaurav Malhotra,Uday N Nayak, Ramesh V Asopa, MGR Rajan

Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, Parel, Mumbai, Maharashtra, India

Objectives: Cardiac dysfunction causing renal disorder and vice versa is well known. The aim of this pilot study was to determine, whether technical modification of simultaneously evaluating renal functions in patients undergoing myocardial perfusion imaging (MPI) with Tc-99m MIBI, was feasible and comparable to the standard Tc-99m DTPA renogram.

Materials and Methods: The study group included 8 males (40-68 years) and 2 females (48, 68 years). They underwent rest MPI with 99mTc MIBI injection under gamma camera in a standard renal acquisition protocol followed by MPI SPECT. All patients were subjected to the standard 99mTc DTPA renogram within 1-20 days of 99mTc MIBI scan (mean: 10.5 days). Both MIBI and DTPA renal studies were analyzed and compared in each patient. In addition 99mTc MIBI study was analyzed separately for evaluating cardiac functions.

Results: Qualitatively, renal dynamic images of Tc-99m MIBI scan were comparable to Tc-99m DTPA scan. Gamma camera clearance (ml/min) of 99mTc DTPA was expressed as GFR where that of 99mTc MIBI was expressed as ‘MIBI clearance’. GFR and MIBI clearance in patients with EF ≤45% (n = 5) was 77.2 ± 22.3 and 161.2 ± 21.4 respectively while in patients with EF >45% (n = 5) these were 91.1 ± 33.1 and 163.2 ± 34.3 respectively (statistically insignificant). There was a strong correlation (0.82) between GFR and 99mTc MIBI clearance in all patients. GFR and 99mTc MIBI clearance/% uptake for each kidney were not significantly different in all patients (9.02 ± 0.19 and 9.4 ± 0.07 for DTPA and MIBI respectively).

Conclusions: Simultaneous evaluation of 99mTc MIBI renal clearance is a reliable marker for kidney function in patients undergoing myocardial perfusion study and it correlates well with GFR by gamma camera technique. We suggest that due to unequal extraction of 99mTc DTPA and 99mTc MIBI, expressing the clearance as per % uptake of respective tracer is a new and comparable parameter which should be used.

Indian J Nucl Med. 2013 Dec;28(Suppl 1):S1–S2.

Card-04: Use of resting electrocardiogram and echocardiography in evaluation of attenuation artefacts in myocardial perfusion images

Mattakarottu Joseph Jacob

Department of Nuclear Medicine, Indian Naval Hospital Ship Asvini, Colaba, Mumbai, Maharashtra, India

Objective: The aim of this study was to evaluate the role of resting electrocardiogram (ECG) and echocardiogram while interpreting attenuation artifacts in myocardial perfusion images.

Materials and Methods: Twenty patients (age range 36-70 years [mean age 55 years]) referred from cardiology center for stress myocardial perfusion study were included in this prospective study. There were 06 females and 14 male patients in the study group. Patient underwent single day stress–rest protocol study using 99m-Tc sestamibi as tracer and siemens dual head E soft gamma camera for imaging. All patients underwent gated SPECT study. Diaphragmatic as well as breast attenuation artifacts were analyzed by gated image as well as presence or absence of “R” wave in ECG. This was counterchecked with the echocardiography finding.

Results: In seven patients, there was fixed perfusion defect in inferior wall in perfusion images. Gated SPECT image showed wall motion in this region. Electrocardiogram showed “R” wave in inferior leads indicating that the area is viable and contracting. Echocardiography showed normal wall motion in inferior wall. In two female patients, there was fixed perfusion defect in anterior wall in perfusion image with normal wall motion in gated SPECT image and normal “R” wave in anterior leads in ECG. Echocardiography showed normal wall motion in these areas.

Conclusion: “R” wave in resting ECG is a reliable marker of viability and contractility of myocardial segments and this can be used as additional information to clear doubt of scar in perfusion images along with gated SPECT and echocardiography and will be very useful in centers with no facility for echocardiography. Careful study of ECG will avoid wrong reporting of fixed perfusion defect due to attenuation artifacts in myocardial perfusion images.

Indian J Nucl Med. 2013 Dec;28(Suppl 1):S1–S2.

Card-05: Synthesis and bio-evaluation of novel 99mTC-hynic-fatty acid complexes for their potential use as myocardial imaging agent

Abhishek Sharma, Anupam Mathur, VV Murhekar, Madhav B Mallia1, HD Sarma2, Uma Sheri, SS Sachdev, Sharmila Banerjee1

Radiopharmaceuticals Program, Board of Radiation and Isotope Technology, 1Isotope Application and Radiopharmaceuticals Division, 2Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

Objective: 123I-labeled fatty acids are used for early detection of myocardial abnormalities in high risk patients. The inherent problems associated with the use of cyclotron produced radionuclide, 123I, necessitate the need for 99mTc based derivatives for the aforementioned application. Though a number of 99mTc based derivatives have been evaluated but none of them represented characteristics suitable for clinical use. In this regard, two novel fatty acid derivatives have been synthesized and radiolabeled with 99mTc via 99mTc-HYNIC chemistry.

Materials and Methods: The two fatty acids utilized were 11 and 12 carbon fatty acids. The fatty acid-HYNIC conjugates were prepared in five step synthetic procedure. In brief, reactive form of hydrazino-nicotinamide (HYNIC) i.e. succinimidyl 6-BOC-HYNIC was synthesized from 6-chloro-nicotinic acid. This was then reacted with 11 and 12 amino fatty acids respectively to yield 11 carbon and 12 carbon HYNIC-fatty acid conjugates, which on subsequent de-protection gave the desired target ligands. The conjugates were characterized by 1H-NMR and labeled with 99mTc using Tricine and ethylenediamine diacetic acid (EDDA) as co-ligands. The radiolabeling procedure followed for both the synthesized HYNIC-fatty acid conjugates is same. 99mTcO4- (30 mCi, 0.5 mL) was added to a mixture of tricine (40 mg), EDDA (10 mg), HYNIC-fatty acid (2-3 mg) and SnCl2 (100 μg) and heated in boiling water for 30 min. The complexes were characterized by HPLC and obtained in high labeling yield and purity >70%.

Results: Bio-distribution studies of the two 99mTc-EDDA-HYNIC-fatty acid complexes showed initial myocardial uptake at 2 min, however retention was not observed over time. The initial uptake and retention in the target organ was found to increase with chain length with 12 carbon chain showing superior behavior.

Conclusion: The rapid clearance of the complexes from the myocardium limits the utility of the synthesized complexes for myocardial imaging.

Articles from Indian Journal of Nuclear Medicine : IJNM : The Official Journal of the Society of Nuclear Medicine, India are provided here courtesy of Wolters Kluwer -- Medknow Publications

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