Incidentally detected diaphragmatic eventration as para-cardiac thoracic activity on myocardial perfusion imaging.

Diaphragmatic eventration is the elevation of hemi-diaphragm without any disruption to diaphragmatic continuity which can be congenital or acquired. The most common acquired cause is phrenic nerve paralysis due to traumatic causes and is usually incidentally diagnosed on chest radiograph or computed tomography. We hereby report a case of a patient who had road traffic accident with fracture of the left proximal femur. Stress Myocardial Perfusion Imaging (MPI) done for pre-operative clearance showed an incidental tracer avidity adjoining to left myocardium in the thorax. It was confirmed on anatomical imaging to be gastric cavity uptake due to diaphragm eventration.

Comparison of positional artifacts in myocardial perfusion imaging in supine and semi-reclining position using dedicated D-SPECT cardiac camera: validation using CT based attenuation correction.

BACKGROUND: Soft-tissue attenuation remains a major limitation of SPECT-MPI which interferes with the diagnosis of CAD. The current study aims to evaluate the pattern of attenuation artifacts in supine and semi-reclining positions on CZT cardiac camera and their interaction with gender, BMI and stress protocols. METHODS: We prospectively analysed 150 patients acquired in supine and semi-reclining positions on CZT camera. The images were evaluated for severity and extent of defect using 17-segment model. An additional CT scan was acquired to generate AC image in the first 50 patients studied to assist investigator learning for comparison of artifact vs true defects in the two SPECT systems. The defects present in one position or showing change in severity within two positions were considered as positional artifacts and further validated using CTAC supine image. RESULTS: In overall analysis, higher extent and severity of positional artifacts were observed more in semi-reclining position affecting the apex, apico-inferior, inferolateral and inferoseptal segments. Females showed more positional artifacts than males with inferior wall attenuation in the semireclining position and anterior wall attenuation in the supine position. A positive correlation of the extent and severity of positional artifacts was noted with an increasing BMI. In patients with BMI > 30, mid inferior and inferolateral segments were most affected followed by anterior wall segments. Highest correction of artifactual perfusion defects by CTAC was noted in inferior wall followed by inferolateral segments. CONCLUSION: The incidence of positional artifacts was greater in semi-reclining position in females, higher BMI groups and adenosine stress subsets. Knowledge of the pattern of positional artifacts appears to be a reliable alternative of CTAC for correct interpretation of myocardial perfusion images.

Radiation Exposure to the Personnel Performing Myocardial Blood Flow Quantification Study Using 13N-ammonia Positron Emission Tomography/Computed Tomography.

Purpose: The present study aimed to evaluate radiation exposure to staff performing coronary flow reserve (CFR) measurement using 13N-ammonia. Materials and Methods: The radiation exposure rate during the administration of 13N-ammonia for the rest and stress part of the study was noted using an ionization chamber-based calibrated survey monitor. The radiation exposure to persons involved in dispensing radioactivity (D1), administering radioactivity (D2) and monitoring the patient during pharmacological stress (D3) were measured using an energy compensated Si-diode personal pocket dosimeter. Results: The average dose received by individuals with dosimeters D1, D2, and D3 was 1.28 ± 0.79 µSv, 1.56 ± 0.51 µSv, and 0.88 ± 0.97 µSv per injection, respectively, during the rest of study and 1.56 ± 0.96 µSv, 2.64 ± 1.22 µSv, and 2.2 ± 1.7 µSv per injection, respectively, during stress study. The average exposure rate during the administration of 13N-ammonia at 0.5 m and 1.5 m from the injection site was found to be 259 µSv/h and 53.4 µSv/h, respectively, during the rest study and 301 µSv/h and 67.25 µSv/h, respectively, during stress study. Conclusion: The exposure to the staff performing CFR study with 13N-ammonia was well within prescribed limits by the International Commission on Radiological Protection 103. The CFR measurement with 13N-ammonia positron emission tomography/computed tomography can be included in routine workups of cardiac patients without the fear of radiation exposure.

Cold kit for Rhenium-188 microspheres based selective intra-arterial therapy (SIRT): Preparation, characterization and feasibility study.

Selective-intra-arterial radionuclide therapy (SIRT) using radiolabeled microspheres are being widely employed for the delivery of therapeutic radioisotope to liver cancers by exploiting the dual blood supply to liver. It delivers the therapeutic radiations to tumor and spares the healthy liver. Several radiolabeled microspheres formulations, labelled with 90Y, are commercially available. However, high-cost leads to unaffordability for several patients. 188Re-based therapy seems affordable due to commercial availability of 188W/188Re generator that have long shelf-life of more than 6 months. To provide affordable solution, the microsphere cold kit with quick and facile methodology for 188Re radiolabeling has been developed. The microsphere cold kit has been characterized for their physicochemical properties. The Quality Control (QC) tests were also performed for clinical application. The feasibility studies were performed to study distribution and retention of 188Re microspheres in tumor. The results demonstrated that the developed cold kit enables facile and quick radiolabeling with 188Re. 188Re microspheres showed good retention in tumor and found suitable for SIRT.

18F-NaF PET uptake characteristics of coronary artery culprit lesions in a cohort of patients of acute coronary syndrome with ST-elevation myocardial infarction and chronic stable angina: A hybrid fluoride PET/CTCA study.

BACKGROUND: 18F-NaF PET/CT identifies high-risk plaques due to active calcification in coronary arteries with potential to characterize plaques in ST-elevation myocardial infarction (MI) and chronic stable angina (CSA) patients. METHODS: Twenty-four MI and 17 CSA patients were evaluated with 18F-NaF PET/CTCA for SUVmax and TBR values of culprit and non-culprit plaques in both groups (inter-group and intra-group comparison), and pre- and post-interventional MI plaques sub-analysis. RESULTS: Culprit plaques in MI patients had significantly higher SUVmax (1.6; IQR 0.6 vs 1.3; IQR 0.3, P = 0.03) and TBR (1.4; IQR 0.6 vs 1.1; IQR 0.4, P = 0.006) than culprit plaques of CSA. Pre-interventional culprit plaques of MI group (n = 11) revealed higher SUVmax (P = 0.007) and TBR (P = 0.008) values than culprit CSA plaques. Culprit plaques showed significantly higher SUVmax (P = 0.006) and TBR (P = 0.0003) than non-culprit plaques in MI group, but without significant difference between culprit and non-culprit plaques in CSA group. With median TBR cutoff value of 1.4 in MI culprit plaques, 6/7 plaques (85.7%) among the event prone non-culprit lesions had TBR values > 1.4 in CSA group. CONCLUSION: The study shows higher SUVmax and TBR values in MI culprit plaques and comparable TBR values for event prone plaques of CSA group in identifying high-risk plaques.

Exploring the potential utilities of 99mTc-labeled RBC-equilibrium radionuclide angiocardiography in transfusion-dependent ß-thalassemia major patients.

AIMS: 99mTc-labeled RBC-equilibrium radionuclide angiocardiography (ERNA) is done in transfusion-dependent beta-thalassemia major (ß-TM) patients routinely for cardiac dysfunction. This prospective study aimed at evaluating the potential of ERNA in demonstrating the bone marrow hyperplasia as an adjunct biomarker for monitoring the adequacy of blood transfusions in transfusion-dependent ß-TM patients. MATERIALS AND METHODS: One hundred and twenty-six patients of ß-TM (study group) and 30 nonthalassemic patients (control) underwent ERNA study with an additional whole-body imaging. We quantitated the normalized bone marrow tracer uptake (due to marrow hyperplasia) and hepatic tracer uptake (indicator of hepatic perfusion) in both the groups on whole-body imaging. Liver and myocardial iron deposition were evaluated with T2* MRI in the thalassemic group. RESULTS: ß-TM group showed significantly increased mean normalized marrow count (MN) compared to the control group (P < 0.001) reflecting peripheral marrow hyperplasia (indirect marker for blood transfusion inadequacy). The hematological parameters in the study group showed a negative correlation with MN, without such correlation in the control group. The study group showed greater derangement in hepatic perfusion with significantly less mean normalized hepatic tracer uptake (HN) compared to the control group. Hepatic iron deposition (evaluated with T2* MRI) also showed a negative correlation with hepatic perfusion parameter (HN) assessed by ERNA, though myocardial iron deposition did not show any significant correlation with cardiac systolic/diastolic parameters evaluated by ERNA in the study group. CONCLUSION: ERNA study with these novel parameters (MN and HN) may have the potential to assess peripheral marrow hyperplasia and derangement in hepatic perfusion in transfusion-dependent ß-TM.

Impact of curative parathyroidectomy on left ventricular functions assessed with 2D ECHO and MUGA study.

Objectives: Primary hyperparathyroidism (PHPT) is associated with increased cardiovascular morbidity and mortality with inconsistent results on the reversibility of cardiovascular changes after parathyroidectomy (PTx). The present study was undertaken to evaluate both structural and functional cardiac changes and their reversal after PTx in patients with PHPT. Material and Methods: Thirty patients of symptomatic PHPT without cardiovascular risk factors were evaluated prospectively by means of 2D echocar- diography (ECHO) and Multigated Acquisition (MUGA) study before surgery and six months after curative parahyroidectomy. Results: Nine of 30 patients had hypertension which improved in two after PTx (p 0.20). Two patients had left ventricle hypertrophy on 2D ECHO pre- operatively which improved after PTx (p <0.001). Left ventricular ejection fraction (LVEF) did not show significant change before and after PTx on 2D ECHO. Nine out of 30 patients had hypertension which improved in two after PTx (p 0.20). Two patients with left ventricle hypertrophy on 2D ECHO preoperatively improved after PTx (p <0.001). Left ventricular ejection fraction (EF) did not depict significant change before and after PTx on 2D ECHO. Whereas, four out of six patients with preoperative EF <50% representing systolic dysfunction on MUGA study showed improvement after PTx. On 2D ECHO, eight patients depicted diastolic dysfunction which improved in six patients after curative surgery (p= 0.07). However, on MUGA study, 13 pa- tients presented with tTPF >180 ms indicating diastolic dysfunction, of which ten showed improvement after PTx (p= 0.007). Conclusion: The present study analyzed preoperative and postoperative cardiac function using both 2D ECHO and MUGA study. MUGA study provided a more objective assessment of the cardiac function by determining left ventricular ejection fraction and diastolic dysfunction.

Prominent aortic radiotracer activity on equilibrium radionuclide ventriculography (ERNV) due to anterior transposition of aorta: A clue to diagnosing levo-transposition of great arteries (L-TGA) ?

Levo-transposition of great arteries (L-TGA) is a rare acyanotic congenital heart anomaly characterized by transposition of morphological left and right ventricles along with their corresponding atrio-ventricular valves in addition to transposition of primary arteries. Many cases of L-TGA are asymptomatic and are diagnosed accidently in adulthood during workup of other conditions. We hereby report a patient with incidentally diagnosed L-TGA who was subjected to Equilibrium Radionuclide Ventriculography (ERNV) for assessment of ventricular function. Planar ERNV images in best septal view showed prominent tracer activity in the anteriorly transposed aorta which can be a helpful clue to raise the suspicion of L-TGA in an asymptomatic adult undergoing ERNV.

Hepato-cardiac juxtaposition secondary to right hemi-diaphragmatic eventration on 99mTc-Sestamibi myocardial perfusion scintigraphy.

Liver radiotracer activity interfering with the inferior myocardial wall in a patient undergoing myocardial perfusion imaging (MPI) with 99mTc-Sestamibi is a known pitfall. We report a patient with pituitary macroadenoma who was subjected to stress-MPI study for pre-anesthetic clearance. The post-stress raw image showed the liver radiotracer activity in close approximation to the anteroseptal wall of the left ventricular myocardium, secondary to right hemi-diaphragmatic eventration.

Freeze-dried microspheres for selective intra-arterial radionuclide therapy: an affordable solution.

OBJECTIVE: Selective intra-arterial radionuclide therapy (SIRT) using radiolabelled microspheres is for the delivery of therapeutic radioisotope to liver cancers and thus, sparing healthy liver. Several radiolabelled microspheres are commercially available. The main issue associated with these microspheres is affordability. Re-188 is a generator produced radionuclide, emits high energy therapeutic beta particle and imageable gamma photons for pre- and post-therapy dosimetry. METHODS: Tc-99m/Re-188 labelled microspheres have been developed and quality control tests have been performed for suitable clinical use. The clinical studies with Re-188 microspheres for SIRT have been performed. Post-therapy images were acquired for dosimetry. RESULTS: The microspheres were found to possess spherical morphology of less than 20 µm size. The quality control revealed the suitability of microspheres for intravenous administration. The preliminary studies in thirty patients demonstrated good retention in tumor and high tumor to normal liver ratio. Re-188 microspheres were well tolerated by patients. Same microspheres labelled with either Tc-99m or Re-188 were used for pretherapy dosimetry and Re-188 labeled microspheres for therapy (SIRT) as a single-day procedure. CONCLUSION: The freeze-dried microspheres may emerge as highly cost-effective candidates for both pre-therapy dosimetry and SIRT and may benefit a large population with inoperable liver cancer.

225Ac-PSMA-617 Radioligand Posttherapy Imaging in Metastatic Castrate-Resistant Prostate Cancer Patient Using 3 Photopeaks.

PSMA-based radioligand therapies have shown the beneficial effect in metastatic castrate-resistant prostate cancer (mCRPC) patients when they become refectory to the established treatments with associated potential toxicities and high mortality rate. Ac-PSMA therapy is known to be remarkably effective in substantially pretreated mCRPC patients. However, posttherapy imaging is usually not performed as alpha emitters are really difficult to image. We presents a patient of mCRPC treated with Ac-PSMA-617, and his posttherapy whole-body scans acquired by using 3 different photopeaks (78, 218, and 440 keV) fairly demonstrated the tracer's distribution and the efficacy of targeted alpha therapy.

Effect of ursodeoxycholic acid in facilitating early hepatic clearance of radiotracer among patients undergoing 99mTc-sestamibi myocardial perfusion scintigraphy: A randomized double blind placebo controlled parallel trial.

BACKGROUND: Infra-cardiac tracer activity due to persistent hepatic activity interferes in inferior and infero-septal wall assessment during 99mTc-MIBI SPECT/CT myocardial perfusion scintigraphy (MPS) in evaluation of patients with coronary artery disease. It affects image interpretation with increased study duration. Ursodeoxycholic acid (UDCA) is known to enhance hepatic excretion of bilirubin and bile salts, though its role in enhancing the hepatic tracer clearance in facilitating cardiac imaging is not known. METHODS: This prospective, randomized double-blind, placebo controlled clinical trial of 120 patients, referred for adenosine stress or viability MPS studies were randomized 1:1 to receive either UDCA or placebo. Outcome was quantitative & qualitative improvement in imaging for better interpretation and to reduce the waiting time for scan. RESULTS: 118 participants (59 ± 11.9 years; 84 men) underwent adenosine stress MPS or viability MPS. Sixty participants had UDCA while 58 had placebo intervention. The study showed significant decrease in liver counts with improved myocardial to liver ratio at 30 and 60 minutes in adenosine stress MPS group, and marginally significant alteration in liver counts at 60 minutes in viability MPS group receiving UDCA, resulting in better images. CONCLUSION: UDCA intervention in MPS provides early and better image due to faster hepatic tracer clearance.

Association of use of proton pump inhibitors and H2 antagonists with stomach wall uptake in 99mTc-methoxy-isobutyl-isonitrile (MIBI) myocardial perfusion imaging.

BACKGROUND: Stomach wall uptake (SWU) of tracer in 99mTc-MIBI myocardial perfusion imaging (MPI) occasionally leads to imaging artifacts, thereby lowering the diagnostic accuracy. It is less-studied phenomenon for possible link with proton pump inhibitors (PPIs) intake. This prospective work looked for association of SWU with PPI intake and compared its incidence with H2 antagonists (H2A) users and patients not on either gastroprotective medication. METHODS: One hundred fifty-six patients undergoing one day stress/rest 99mTc-MIBI SPECT-MPI were distributed into four groups: control group (n = 48, not on any gastroprotective medication), PPI group (n = 47, on PPI treatment), H2A group (n = 19, on H2A therapy), and intervention group (N = 42, PPI discontinued for 3 days before MPI). Poststress planar images were analyzed for clinically relevant SWU. RESULTS: Clinically relevant SWU was seen in 36% of PPI group patients compared to 8% in the control group, 10.5% in the H2A group, and 9.5% in the intervention group, respectively, with statistically significant difference. Only 1/40 patients undergoing exercise stress showed clinically relevant SWU compared to 26/116 patients undergoing adenosine stress (P = .020). CONCLUSION: Patients on PPIs scheduled for vasodilator stress MPI may discontinue PPIs for 3 days, or replace with H2A to reduce the incidence of clinically relevant SWU associated with PPI therapy.

Prognostic value of left ventricular mechanical dyssynchrony indices in long-standing type II diabetes mellitus with normal perfusion and left ventricular systolic functions on SPECT-MPI.

OBJECTIVE: To test whether phase analysis indices from SPECT-MPI for left ventricular mechanical dyssynchrony (LVMD) are predictors of major adverse cardiac events (MACEs) in long-standing diabetes mellitus (DM). METHODS: A total of 136 DM patients with normal perfusion and left ventricular systolic functions were followed up for about two years and divided into two groups according to the presence and the absence of MACEs. RESULT: Thirteen (9.5%) patients experienced MACEs during follow-up. Patients experiencing MACEs showed significantly higher phase standard deviation (PSD) and wider phase bandwidth (PBW) than those who did not. Moreover, both PSD and PBW showed significant correlations (r = 0.25 and 0.27; P < 0.05) with duration of DM. Logistic regression analysis revealed significant associations of DM duration, microvascular complications, and LVMD indices for predicting MACEs. Kaplan-Meier event-free survival analysis revealed significantly higher rate of MACEs (Logrank = 10.02; P = 0.001) in patients with high PSD and wide PBW. An overall fit model consisting of high-PSD and wide-PBW group was improved with the addition of microvascular complications (χ2 = 15.9; P = 0.03) and further by addition of DM duration of ≥ 15 years (χ2 = 24.3; P = 0.007) as variables. CONCLUSION: LVMD indices are novel prognostic markers in diabetic patients with normal perfusion and left ventricular systolic functions and their increases in magnitudes with DM-duration and in the presence of microvascular complications.

Evaluation of left ventricular mechanical dyssynchrony with phase analysis in end-stage renal disease patients with normal gated SPECT-MPI.

Phase analysis using gated single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) is a relatively new tool for the assessment of ventricular synchrony. Hypertension, diabetes, renal diseases, and dyslipidemia may affect the phase parameters though their impact is not well understood. The present study aimed to evaluate the incidence of the left ventricular mechanical dyssynchrony (LVMD) in end-stage renal disease (ESRD) patients with normal gated SPECT-MPI and QRS duration (<120 ms) on electrocardiogram. Data of 129 patients (86 males) referred for gated SPECT-MPI for their pretransplant evaluation with normal gated stress SPECT-MPI (SSS <3 and ejection fraction ≥50%) were included in the study analysis. Documented clinical history along with confounding factors such as hypertension, dyslipidemia, smoking, and alcoholism were evaluated. Left ventricle functional (end-diastolic, end-systolic, and LV myocardial volume) and phase parameters (phase standard deviation [PSD], phase bandwidth [PBW] and entropy) were calculated using the QPS-QGS program. LVMD was noted in 36 (28%) of ESRD patients with normal QRS duration and gated SPECT-MPI. The mean attenuated corrected LV myocardial volume, ejection fraction, mean PSD, and PBW values were 84.3 ± 38.1 ml, 65.3 ± 13.5%, 9.8° ± 3.9°, and 61.4° ± 24.7°, respectively. The LV myocardial volume shows statistically significant correlation with the phase parameters (r = 0.31-0.47; P < 0.001). LVMD is present in a significant number of ESRD patients, and its extent is more with increase in LV myocardial volume. It may have an additional role in risk-stratification for cardiovascular disease in ESRD patients.

Impact of hibernating and viable myocardium on improvement in perfusion and left ventricular ejection fraction after coronary artery bypass graft.

OBJECTIVES: The association between the extent and degree of perfusion-metabolism mismatch and improvement in perfusion and left ventricular ejection fraction (LVEF) after revascularization was assessed. The secondary aim was to identify the best precoronary artery bypass graft surgery (pre-CABG) PET parameter, if any, to predict the improvement in the perfusion and LVEF after CABG. METHODS AND RESULTS: Overal, 31 patients (mean age: 58+8.3 years) with ischemic left ventricle dysfunction underwent NH3 and F-FDG PET for the assessment of myocardial viability. CABG was performed in these patients and after a mean interval of 3 months, NH3 PET was repeated. The percentages of viable myocardium (VM), hibernating myocardium, degree of mismatch, and LVEF in pre-CABG PET were calculated. These were compared, the median [INCREMENT]LVEF and percent increase in perfusion being 5 (interquartile range: 3-9) and 78.7 (interquartile range: 51.3-100), respectively. No significant association was observed between the severity or extent of perfusion defect/mismatch and improvement in perfusion or LVEF after CABG. Patients with at least 65% VM predicted a 5-unit increase in LVEF at 88.9% sensitivity (P=0.1). CONCLUSION: There was no significant relation between the severity and extent of perfusion-metabolism mismatch with improvement in perfusion and LVEF after CABG. After CABG for ischemic left ventricle dysfunction, VM shows a tendency toward better improvement in LVEF.

Left ventricular mechanical dyssynchrony assessment in long-standing type II diabetes mellitus patients with normal gated SPECT-MPI.

BACKGROUND: Assessment of left ventricular mechanical dyssynchrony (LVMD) using phase analysis of gated SPECT-MPI is well established. However, there is little information about the influence of diabetes mellitus on phase analysis. The present work was to evaluate the LVMD in longstanding type II diabetes mellitus (DM) patients with normal gated SPECT-MPI. METHODS: Retrospective analysis of 146 (86 type II diabetics for > 5 years' duration and 60 nondiabetics) consecutive patients with normal gated SPECT-MPI and adequate LVEF was done. Sixty age- and sex-matched nondiabetic served as control. LVMD was determined from the cutoff values (> mean + 2 SD) observed for phase standard deviation (PSD) and phase bandwidth (PBW) from the control subjects. Multivariate logistic regression analysis was applied to assess the correlation between various confounding factors. RESULTS: LVMD was detected in 24 (28%) diabetic patients with the pre-defined cut-off values for PSD (> 10.8) and PBW (> 35.6) derived from the controls. Hyperlipidemia, overweight/obesity, duration of DM and its long-term complications were independently associated with LVMD, with long-term complications being the highest risk factor (OR 28.00; P < .001). CONCLUSION: The evolution time of the patients with type II diabetes mellitus affects the left ventricular mechanical synchrony.