Nosheen Fatima

Recent developments and future prospects of SPECT myocardial perfusion imaging.

Myocardial perfusion SPECT imaging is the most commonly performed functional imaging for assessment of coronary artery disease. High diagnostic accuracy and incremental prognostic value are the major benefits while suboptimal spatial resolution and significant radiation exposure are the main limitations. Its ability to detect hemodynamic significance of lesions seen on multidetector CT angiogram (MDCTA) has paved the path for a successful marriage between anatomical and functional imaging modalities in the form of hybrid SPECT/MDCTA system. In recent years, there have been enormous efforts by industry and academia to develop new SPECT imaging systems with better sensitivity, resolution, compact design and new reconstruction algorithms with ability to improve image quality and resolution. Furthermore, expected arrival of Tc-99m-labeled deoxyglucose in next few years would further strengthen the role of SPECT in imaging hibernating myocardium. In view of these developments, it seems that SPECT would enjoy its pivotal role in spite of major threat to be replaced by fluorine-18-labeled positron emission tomography perfusion and glucose metabolism imaging agents.

Pulmonary embolism in pregnancy: a diagnostic dilemma

The diagnosis of PE in pregnancy poses a challenge due to pregnancy-related physiological changes. Missing the PE or wrongly treating a pregnant woman for PE has serious clinical consequences. There has been concern over the use of radiation-based imaging modalities due to risk of teratogenicity and oncogenicity. This review is focused on various diagnostic options and risks of radiation to the fetus and mother from radiation-based procedures.

Assessing adriamycin-induced early cardiotoxicity by estimating left ventricular ejection fraction using technetium-99m multiple-gated acquisition scan and echocardiography.

BackgroundAdriamycin cardiotoxicity begins with the first dose of therapy. The insult may be subclinical initially, but with continued treatment can result in clinical congestive heart failure. Therefore, a study for the detection of early cardiotoxicity of adriamycin by left ventricular ejection fraction (LVEF) estimation using technetium (Tc)-99m multiple-gated acquisition (MUGA) scan and echocardiography (ECHO) was conducted. MethodsLVEF was assessed in 42 patients with different cancers, advised to receive adriamycin (average received dose=95.2±6.82 mg/cycle, protocol dose=65±10 mg/m2) in each of six cycles. The percentage of LVEF (%LVEF) was determined as a baseline after every successive cycle, simultaneously, by a Tc-99m MUGA scan (reference method) and ECHO. ResultsA significant decline of 12.17±5.01 and 9.26±4.82 (P<0.001) in %LVEF was noted at the end of adriamycin therapy, estimated by a Tc-99m MUGA scan and ECHO respectively. Thirteen of 42 (31%) and six of 42 (14%) patients developed protocol-defined cardiotoxicity, determined by a Tc-99m MUGA scan and ECHO, respectively. The incidence of cardiotoxicity was 2.4, 2.4, 4.8, 16, and 31.2% at the median cumulative adriamycin dose of 210, 380, 450 , 550 , and 615 mg/m2, respectively. ConclusionSubclinical adriamycin cardiotoxicity was detectable from the third cycle and if not detected earlier continued therapy may progress to severe and irreversible cardiotoxicity. A decline of 5% or more of %LVEF instead of 10% should be considered as a significant marker of subclinical cardiotoxicity. A Tc-99m MUGA scan is more sensitive than ECHO for the estimation of subtle changes in %LVEF. Ideally, %LVEF must be determined at baseline and after every cycle, and if not possible then preferably from the third cycle onwards.

Controversies about Radioactive Iodine-131 Remnant Ablation in Low Risk Thyroid Cancers: Are We Near A Consensus?

Well differentiated thyroid cancers (WDTC), including papillary (80%) and follicular (10%) types, are the most common endocrine cancers globally. Over the last few decades most the diagnosed cases have fallen into low risk categories. Radioactive iodine-131 (RAI) has an established role in reducing recurrence and improving the survival in high risk patients. In patients with primary tumor size <1 cm, RAI is not recommended by many thyroid societies. However, low risk WDTC has been an arena of major controversies, most importantly the role and dose of adjuvant RAI for remnant ablation to minimize chances of recurrence and improving survival. This review is an attempt to update readers about the previous and existing practice based on results of non- randomized trials and evolving trends fueled by recently published randomized studies.

Lower Incidence but More Aggressive Behavior of Right Sided Breast Cancer in Pakistani Women: Does Right Deserve More Respect?

BACKGROUND The aim of this epidemiological study was to establish the laterality of breast cancer (BC) and its association with size, receptor status of the primary tumor and bone metastasis (BM) in a local population. MATERIALS AND METHODS This retrospective study included cases of BC from Jan-2009 to Dec-2011 who were referred for metastatic work up or follow up survey with Technetium-99m MDP bone scan (BS) to the Nuclear Medicine Department of Karachi Institute of Radiotherapy and Nuclear Medicine (KIRAN). A total of 384 patients out of 521 were included and all reviewed for age, primary tumor size (PTS), laterality, receptor status like estrogen receptor (ER) progesterone receptor (PR) and Her-2-Neu receptor, presence or absence of BM with sites of involvement and time interval between diagnosis of BC and appearance of BM. RESULTS The left to right sided BC proportion was significantly higher than unity (59%:41%; p<0.001). The right sided BC was observed in younger age group (46:52 years; p<0.0001) and with a smaller PTS than the left sided (3.43:4.15 cm; p<0.0001). The patients with BM had relatively higher negative receptor status with a significant predominance of right sided BC. The overall incidence of BM on BS was 28% and relatively higher in right than left breast (33%:24% p=0.068). The average number of BM sites was also significantly greater for the right side (6:4, P<0.0001). The % cumulative risk of BM in right breast was noted at significantly smaller PTS than left side with log rank value of 5.579; p<0.05. The Kaplan Meier survival plot for event free survival of BM in left sided BC was significantly higher than for the right side (log rank value=4.155, p<0.05), with an earlier appearance of BM in right BC. CONCLUSIONS 1) A left sided predominance of BC was seen in local population; 2) right sided BC had a more aggressive behavior with extensive and earlier appearance of BM at relatively younger age, smaller PTS and receptor (s) negativity.

Threshold Primary Tumour Sizes for Nodal and Distant Metastases in Papillary and Follicular Thyroid Cancers

BACKGROUND In papillary and follicular thyroid cancers (PTC, FTC), nodal and distant metastasis are generally considered important determinants of recurrence and survival, respectively. However, there is no consensus about the threshold primary tumour size (PTS) for these determinants. The aim of this study was to assess size relationships for developing nodal, pulmonary, bone and overall distant metastases. METHODS This prospective study covered 139 (93 females and 46 males) consecutive biopsy proven patients with PTC (114/139, mean age 41.0 ± 15.7 years, M: F, 35%:65%) and FTC (25/139, mean age 39.2 ± 14.3 years, M: F: 24%:76%). RESULTS Average primary tumor size was 23.4 ± 11.1 mm and 26.5 ± 13.1 mm for PTC and FTC respectively (p value=0.223). Nodal metastasis was found more common in PTC than FTC (49% vs 28%, p value <0.05), whereas overall distant metastasis was approximately the same (13% and 24%, p value =0.277); however, bone metastasis was significantly higher in FTC than PTC (24% vs 5%, p value <0.05). Cumulative risk for nodal and distant metastases for FTC and PTC starts at PTS <20 mm and may indicate an unusual aggressive tumor behavior in the studied population. Highest cumulative risk for nodal and pulmonary metastases in PTC and for bone metastasis in FTC was found to be ≥ 50 mm PTS. CONCLUSION We conclude that a PTS of <20 mm may indicate an unusual aggressive tumor behavior with highest cumulative risk for nodal and pulmonary metastases in PTC and for bone metastasis in FTC with a cutoff of ≥ 50 mm.

Comparable Ablation Efficiency of 30 and 100 mCi of I-131 for Low to Intermediate Risk Thyroid Cancers Using Triple Negative Criteria.

BACKGROUND There is controversy about ablation efficacy of low or high doses of radioiodine-131 (RAI) in patients with differentiated thyroid cancers (DTC). The purpose of this prospective study was to determine efficacy of 30 mCi and 100 mCi of RAI to achieve successful ablation in patients with low to intermediate risk DTC. MATERIALS AND METHODS This prospective cross sectional study was conducted from April 2013 to November 2015. Inclusion criteria were patients of either gender, 18 years or older, having low to intermediate risk papillary and follicular thyroid cancers with T1-3, N0/N1/Nx but no evidence of distant metastasis.Thirty-nine patients were administered 30 mCi of RAI while 61 patients were given 100 mCi. Informed consent was acquired from all patients and counseling was done by nuclear physicians regarding benefits and possible side effects of RAI. After an average of 6 months (range 6-16 months; 2-3 weeks after thyroxin withdrawal), these patients were followed up for stimulated TSH, thyroglobulin (sTg) and thyroglobulin antibodies, ultrasound neck (U/S) and a diagnostic whole body iodine scan (WBIS) for ablation outcome. Successful ablation was concluded with stimulated Tg< 2ng/ml with negative antibodies, negative U/S and a negative diagnostic WBIS (triple negative criteria). ROC curve analysis was used to find diagnostic strength of baseline sTg to predict successful ablation. RESULTS Successful ablation based upon triple negative criteria was 56% in the low dose and 57% in the high dose group (non-significant difference). Based on a single criterion (follow-up sTg<2 ng/ml), values were 82% and 77% (again non-significant). The ROC curve revealed that a baseline sTg level ≤ 7.4 ng/ml had the highest diagnostic strength to predict successful ablation in all patients. CONCLUSIONS We conclude that 30 mCi of RAI has similar ablation success to 100 mCi dose in patients with low to intermediate risk DTC. A baseline sTg ≤ 7.4 ng/ml is a strong predictor of successful ablation in all patients. Low dose RAI is safer, more cost effective and more convenient for patients and healthcare providers.

Predictive value of pyramidal lobe, percentage thyroid uptake and age for ablation outcome after 15 mCi fixed dose of radioiodine-131 in Graves' disease

Purpose: The purpose was to find out the efficacy of fixed 15 mCi radioactive iodine-131 (RAI) dose and predictive values of various factors for inducing hypothyroidism in Graves’ disease (GD). Materials and Methods: Retrospective study conducted from January 2012 till August 2014. Patients with GD who had a technetium-99m thyroid scan, thyroid antibodies, received fixed 15 mCi RAI and did follow endocrine clinics for at least 6 months were selected. RAI was considered successful if within 6 months of RAI therapy patients developed hypothyroidism. Results: Of the 370 patients with GD who had RAI during study period, 210 (57%) qualified study criteria. Mean age of patients was 48 ± 15 years with female: male ratio of 69:31, positive thyroid antibodies in 61%, means thyroid uptake of 15.09 ± 11.23%, and presence of pyramidal lobe in 40% of total population. Hypothyroidism was achieved in 161 (77%) patients while 49 (23%) patients failed to achieve it (remained either hyperthyroid or euthyroid on antithyroid medication). Patients who became hypothyroid were significantly younger with higher proportion of presence of thyroid antibodies and pyramidal lobe and lower percentage thyroid uptake than those who failed. Multiple logistic regression analysis revealed that age (odds ratio; OR = 2.074), pyramidal lobe (OR = 3.317), thyroid antibodies (OR = 8.198), and percentage thyroid uptake (OR = 3.043) were found to be significant prognostic risk factors for post-RAI hypothyroidism. Gender was found to have nonsignificant association with the development of hypothyroidism. Receiver operating characteristic analysis revealed age <42 years and thyroid uptake <15% as threshold values for the development of post-RAI hypothyroidism. Conclusion: We conclude that fixed (15 mCi) RAI dose is highly effective in rendering hypothyroidism in patients with GD. Age (≤42 years), thyroid uptake (≤15%) and presence of pyramidal lobe are strong predictors of hypothyroidism and must be considered for selecting optimal RAI dose.

Impact of glycosylated hemoglobin (HBA1C) on the extent of perfusion abnormalities and left ventricular dysfunction using gated myocardial perfusion imaging and clinical outcomes in diabetic patients.

ObjectivesThe aim of the study was to determine the impact of glycosylated hemoglobin (HBA1C) on the extent of perfusion abnormalities and left ventricular dysfunction (LVD) using gated myocardial perfusion imaging (GMPI) and clinical outcomes in diabetic patients. Materials and methodsA total of 1013 individuals (457 diabetic patients and 556 nondiabetic controls) were included in the study. Among the diabetic patients, 254 (56%) were male and 203 (44%) were female, with a mean age of 58±9 years. Stress GMPI was evaluated for the size and severity of perfusion defects, transient ischemic dilation (TID) ratio (>1.22), and LVD. Patients were followed up for 22 months (12–24 months) for fatal myocardial infarction or nonfatal myocardial infarction (NFMI). ResultsGMPI was found to be normal in 49 and 68% (P<0.0001) of diabetic patients and nondiabetic controls, respectively; fixed defects were seen in 21 and 16% (P=0.049), reversible defects in 30 and 16% (P<0.0001), and TID in 19 and 8% (P<0.0001) of participants in the diabetic and nondiabetic groups, respectively. Receiver-operating characteristic curve analysis revealed the diagnostic strength of HBA1C for coronary artery disease at a cutoff value greater than 7.3% (P<0.0001). Fasting blood sugar and duration of diabetes had poor diagnostic strength (P>0.05). The diabetic cohort was divided into group A (HBA1C>7.3%) and group B (HBA1C⩽7.3%). GMPI in groups A and B revealed fixed defects in 33 and 9% and reversible defects in 41 and 22%, respectively; the sum stress score was 6±2 and 5±2, the sum thickness score was 38±8 and 32±6, and %left ventricular ejection fraction was 53±16 and 58±11, with TID in 32 and 8%, in groups A and B, respectively (all with P<0.0001). The Kaplan–Meier survival curves in groups A and B revealed event-free survival of 97.2 and 98.3% for fatal myocardial infarction (P=0.742) and 87.1 and 97.9% for NFMI (P<0.05), respectively. ConclusionHBA1C is a reliable predictor of coronary artery disease and the magnitude of perfusion defects and LVD and the incidence of NFMIs are higher at an HBA1C level greater than 7.3%.

18FDG synthesis and supply: a journey from existing centralized to future decentralized models.

Positron emission tomography (PET) as the functional component of current hybrid imaging (like PET/ CT or PET/MRI) seems to dominate the horizon of medical imaging in coming decades. 18Flourodeoxyglucose (18FDG) is the most commonly used probe in oncology and also in cardiology and neurology around the globe. However, the major capital cost and exorbitant running expenditure of low to medium energy cyclotrons (about 20 MeV) and radiochemistry units are the seminal reasons of low number of cyclotrons but mushroom growth pattern of PET scanners. This fact and longer half-life of 18F (110 minutes) have paved the path of a centralized model in which 18FDG is produced by commercial PET radiopharmacies and the finished product (multi-dose vial with tungsten shielding) is dispensed to customers having only PET scanners. This indeed reduced the cost but has limitations of dependence upon timely arrival of daily shipments as delay caused by any reason results in cancellation or rescheduling of the PET procedures. In recent years, industry and academia have taken a step forward by producing low energy, table top cyclotrons with compact and automated radiochemistry units (Lab- on-Chip). This decentralized strategy enables the users to produce on-demand doses of PET probe themselves at reasonably low cost using an automated and user-friendly technology. This technological development would indeed provide a real impetus to the availability of complete set up of PET based molecular imaging at an affordable cost to the developing countries.