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.

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.

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.

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.

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.

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.

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.

Scintigraphic findings in end-stage liver disease on Tc-99m sestamibi SPECT/CT myocardial perfusion imaging.

Technetium-99m sestamibi myocardial perfusion imaging is commonly employed non-invasive study for evaluation of coronary artery disease; however, incidental extracardiac scintigraphic findings observed may provide additional diagnostic information. The authors present the unusual scintigraphic findings in a case of decompensated liver disease with right hepatic hydrothorax, being planned for orthotopic liver transplant.

Development of Lu-177-trastuzumab for radioimmunotherapy of HER2 expressing breast cancer and its feasibility assessment in breast cancer patients.

HER2/neu is over expressed in 20-25% of breast cancers. HER2 breast cancers are aggressive and are associated with poor prognosis. The aim of this study was to develop the clinical grade Lu-177-trastuzumab and its preliminary evaluation for specific tumor targeting in HER2 positive breast cancer patients. Trastuzumab was conjugated to bifunctional chelator, DOTA, and characterized for integrity and the number of molecules conjugated. Radiolabeling of DOTA-conjugated trastuzumab was optimized using Lu-177. Quality control parameters including radiochemical purity, stability, sterility, pyrogenicity and immunoreactivity were assessed. A preliminary pilot study was conducted on breast cancer patients (n = 6 HER2 positive and n = 4 HER2 negative) to evaluate the ability of Lu-177-trastuzumab for HER2 specific tumor targeting. The conjugates were efficiently labeled with Lu-177 with high radiochemical purity (up to 91%) and specific activity (6-13 µCi/µg). Lu-177-trastuzumab was stable up to 12 hr post labeling. The radioimmunoassay demonstrated good antigen binding ability and specificity for HER2 receptor protein. The patient studies showed the localization of Lu-177-trastuzumab at primary as well as metastatic sites (HER2 positive) in the planar and SPECT/CT images. No tracer uptake was observed in HER2 negative patients that indicated the specificity of Lu-177-trastuzumab. The study demonstrated that in-house developed Lu-177-trastuzumab has specific targeting ability for HER2 expressing lesions and may in future become a palliative treatment option in the form of targeted radionuclide therapy for disseminated HER2 positive breast cancer.

Bone marrow hyperplasia detected by gated blood pool imaging.

Technetium-99m RBC gated blood pool ventriculography study or multigated acquisition (MUGA) is a commonly employed imaging study to determine the left ventricle ejection fraction and regional wall motion. However, tracer distribution at abnormal sites requires further evaluation. We present the case of a young thalassemia patient with significant tracer uptake in the rib cage as observed in the planar images of MUGA study helping in the demonstration of scintigraphic evidence of bone marrow hyperplasia.

Incidental detection of bronchial carcinoid on Tc-99m sestamibi SPECT/CT myocardial perfusion scintigraphy.

Technetium-99m sestamibi MPS is a commonly employed imaging study for myocardial perfusion; however, incidental extracardiac sestamibi uptake requires further evaluation, and the tracer uptake in the thorax/mediastinum may be pathological. The authors present a case of significant extra-cardiac uptake seen on stress MPS images helping in the incidental detection of bronchial carcinoid.

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.