Role of 99mTc-sestamibi Scintimammography in Predicting Response to Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer: A Prospective Study.

Background: Neoadjuvant chemotherapy (NACT) is the first line of management for locally advanced breast cancer (LABC). However, chemoresistance is prevalent in 18%-50% of the cases. One of the important and most studied causes of chemoresistance is P-glycoprotein (Pgp) expression. 99mTc-sestamibi scintimammography may serve as a useful imaging tool to predict Pgp expression, thereby response to NACT. Aim: The aim was to study the role of 99mTc-sestamibi scintimammography in predicting response to NACT in treatment-naive, biopsy-proven LABC patients. Materials and Methods: 99mTc-sestamibi scintimammography (early and delayed images) was performed on a total of 34 patients. Eight patients were lost to follow-up, and only 26 (25 females and 1 male) patients were available for final analysis, with a mean age of 49.7 ± 10.7 years. 99mTc-sestamibi washout rate (WOR) (%) and T/B buildup were calculated. Pre-NACT and Post-NACT tumor sizes were measured clinically, and a % decrease in tumor size was calculated. The WOR and T/B buildup values were correlated with the % decrease in tumor size. Results: We found a statistically significant negative correlation between WOR (%) and % decrease in tumor size and a statistically significant positive correlation between T/B buildup and % decrease in tumor size. Furthermore, we found a positive correlation between the early T/B ratio and the Ki-67 index (P = 0.22). Conclusion: Early categorization of responders and nonresponders can help in optimal therapy planning. 99mTc-sestamibi scintimammography can serve as an imaging marker for Pgp expression, thereby predicting clinical response to NACT in LABC patients. Further studies with larger sample sizes are warranted to consolidate the above findings.

Assessment of Gastric Dysmotility Using Standardized Tc-99m Sulfur Colloid-Labeled Rice Cakes in Diabetic Patients.

Background: Diabetes mellitus is a common lifestyle disease where patients suffer from gastric dysmotility, which is usually underdiagnosed. The aim of this study was to evaluate the utility of Tc-99m sulfur colloid-labeled meal gastric emptying scintigraphy in Type 2 diabetic patients. Methods: A total of 43 patients and 30 controls, satisfying the inclusion criteria from March 2019 to August 2020, were included. Serial planar images were acquired in both anterior and posterior projections for an iso-time of 1 min at 1 min, 60 min (1 h), 120 min (2 h), and 240 min (4 h) after consumption of Tc-99m SC-labeled idly (rice cakes). The gastric emptying was considered delayed if there was <10% emptying at 1 h, <70% emptying at 2 h, and <94% emptying at 4 h. Results: The mean T1/2 was similar among cases (44.11 ± 10.52 min) and controls (49.56 ± 13.44 min, P = 0.056) while the mean gastric emptying at 1 h was slower in cases compared to controls, P = < 0.01. Two cases (4.6%) had delayed gastric emptying while none of the controls had delayed gastric emptying. T1/2 showed no association with duration of diabetes or HbA1c levels (P = 0.76, 0.45) and a weak correlation with fasting blood sugar (FBS) on the day of scan (R value = 0.18). Conclusion: In comparison to controls, diabetic patients had faster gastric emptying with no association with duration of diabetes or HbA1c levels and a weak correlation with FBS on the day of scan.

Utility of Fluorine18 Fluoro-2-deoxy-D-glucose Positron Emission Tomography/Computed Tomography in Metabolic Characterization of Solid Renal Mass Lesion and Localization of Extra Renal Lesions in the Body - A Prospective Study from the Tertiary Care Center in South India.

Purpose of the Study: Renal mass lesions in majority of the cases are due to malignant etiology and about one-third of them are reported with metastatic lesions at the time of presentation. Thus proper investigational workup is needed for staging and thereby treatment planning. The current fluorine18 fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (F18-FDG PET/CT) study was designed to characterize renal mass lesions metabolically and identifying other metabolically active lesions in the body suggesting metastatic disease. Materials and Methods: A total of 24 patients (males - 18 and females - 6) with a mean age of 53.8 ± 12.3 years were recruited in this study for dual time-point PET/CT scan. All patients with renal mass lesions underwent contrast-enhanced CT prior to PET/CT. Metabolic parameters such as maximum standardized uptake value (max.SUV) with a cut off ≥2.5 and retention index (RI) of ≥10% were used to label the lesion as malignant and remaining less than cutoff as benign. The final diagnosis of lesion on imaging was confirmed with a histopathological examination (HPE). Results: Using max.SUV cut off value, 17/24 renal mass lesions were characterized as malignant and remaining 7/24 renal lesions of benign etiology. PET/CT showed sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 80%, 75%, 94.1%, 42.8%, and 79.1%, respectively, by considering HPE as a gold standard. Nine patients were diagnosed with distant site involvement suggestive of metastases. Conclusion: F18-FDG PET/CT can efficiently characterize solid renal mass lesion as benign and malignant using metabolic parameters such as max.SUV and RI. In addition, whole-body survey identified distant site involvement in 25% of the patients, thus contributing change in management.

Utility of Short-Acting Intravenous Insulin Therapy in Preparation of F-18 Fluorodeoxyglucose Positron Emission Tomography Computed Tomography Scan in Cancer Patients Incidentally Detected with High Blood Glucose Levels on the Day of Test.

BACKGROUND: In diabetic (DM) patients, hyperglycemia degrades image quality in F-18 FDG PET CT by altering bio-distribution of FDG in the body and augmenting soft tissue and muscular uptake. We intend to evaluate the use of short acting I.V insulin in minimising the rescheduling of patients detected with FBG>160 mg/dL on the day of scan. AIM AND OBJECTIVES: To show the utility of short acting IV insulin therapy in preparation of cancer patients incidentally detected with high blood glucose levels for F-18 FDG PET CT scan, (>160mg/dL) and to compare the obtained image quality with patients detected with fasting blood glucose level (FBG) <100mg/dL and <160 mg/dL, using visual and semi quantitative methods. MATERIAL AND METHODS: 613 cancer patients referred for PET CT were divided into 3 groups, Group I (n=30): known diabetics (DM) or incidentally diagnosed with FBG >160 mg/dL, Group II (n=349): DM patients with FBG <160 mg/dL (100-160mg/dL), Group III (n=234): Non DM patients FBG <100mg/dL. In Group I short acting insulin was given intravenously using a sliding scale, post insulin after 90 minutes F-18 FDG (radiotracer) injection was given and PETCT scan was obtained 60 mins post radiotracer injection. Qualitative image analysis was done using biodistribution score and quantitative analysis was done by chi square test, ANOVA (analysis of variance) and paired t-test. RESULTS: In group I patients post insulin there was significant decrease in FBG levels (216±22.2 to 136±13.4mg/dL) and acceptable image quality. Comparison of quantitative parameters (mean and maximum SUV calculated by drawing ROI around brain, heart, liver, muscle, subcutaneous fat) among the 3 groups showed significant intergroup difference with p value <0.05. CONCLUSION: This short acting I.V insulin protocol is safe and can be used to obtain optimal quality F-18 FDG PET CT scan images by alleviating the need for rescheduling patients though they present with high glucose levels.

Metachronous Second Primary Malignancies in Known Breast Cancer Patients on 18F-Fluoro-2-Deoxyglucose Positron Emission Tomography-Computerized Tomography in a Tertiary Care Center.

INTRODUCTION: Breast cancer is the most common malignancy among women all over the world, which accounts to 25% of all cancers. In known cases of breast cancer, the risk of developing another denovo malignancy is more when compared to low risk groups, which might be due to common environmental risk factors, treatment induced risk factors, Genetic susceptibility for mutations, presence of cancer syndromes or better detection due to close surveillance. OBJECTIVE: To study the profile of Metachronous 2nd primary malignancies suspected on 18F-FDG PET CT in known Breast cancer patients. In this Retrospective study from January 2014 to April 2018, all the consecutive patients with known Breast cancer, who were referred to Nuclear Medicine department for 18F- FDG PET CT for follow up evaluation were included. Suspected 2nd primary malignancies were correlated with Histopathological examination (HPE). RESULTS: During the study period, a total of 233 Breast cancer patients (all are females), with a mean age of 54.2+13.4 years were studied. On 18F-FDG PET CT scan, suspicion for 2nd primary malignancy was observed in 37 patients. HPE was done in 28/37 patients at the site of suspected lesions. 15/28 were positive for second malignancy, and remaining 13/28 were either a benign pathology or a part of metastatic disease from the primary breast cancer. The sites of 2nd primary malignancies included Contralateral breast in 8/15 (53.3%), Ovary in 2/15 (13.3%), Endometrium in 2/15 (13.3%), Lung in 1/15 (6.6%), Stomach in 1/15 (6.6%) and Urinary bladder in 1/15 (6.6%) patients respectively. The incidence of metachronous 2nd primaries in breast cancer is 67.3 per 1000 breast cancer patients. CONCLUSION: Metachronous second primary cancers in breast cancer patients are not very rare. A high imaging suspicion on 18F-FDG PET CT helps in early detection of 2nd primary cancer, thereby facilitating early and appropriate management.

Unilateral Graves' Disease: The Lesser Known.

BACKGROUND: Here, we present a retrospective study conducted from 2009 to 2018, which showed the presence of unilateral uptake of radioactive tracer on 99mTc thyroid scintigraphy scan in 15 patients with Graves' disease. MATERIALS AND METHODS: All these patients had either clinical features of Graves' disease or elevated thyroid hormone levels along with ultrasonographic features, showing either normal thyroid gland or diffuse thyroiditis. The scintigraphic features revealed increased uptake in one lobe of the thyroid gland with the other lobe being normal. RESULTS: Of the 15 patients, 13 were females and two were males. The mean age of the patients was 47 years with standard deviation of 3.4 years (range 26-70 years). Eight of the 15 patients had increased uptake on the right lobe and seven had increased uptake in the left lobe. CONCLUSION: This study shows that there exists an entity called unilateral Graves' disease which should be further evaluated.

A Prospective Study Comparing Functional Imaging (18F-FDG PET) Versus Anatomical Imaging (Contrast Enhanced CT) in Dosimetric Planning for Non-small Cell Lung Cancer.

OBJECTIVES: 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET-CT) is a well-used and established technique for lung cancer staging. Radiation therapy requires accurate target volume delineation, which is difficult in most cases due to coexisting atelectasis. The present study was performed to compare the 18F-FDG PET-CT with contrast enhanced computed tomography (CECT) in target volume delineation and investigate their impacts on radiotherapy planning. METHODS: Eighteen patients were subjected to 18F- FDG PET-CT and CECT in the same position. Subsequently, the target volumes were separately delineated on both image sets. In addition, the normal organ doses were compared and evaluated. RESULTS: The comparison of the primary gross tumour volume (GTV) between the 18F-FDG PET-CT and CECT imaging revealed that 88.9% (16/18) of the patients had a quantitative change on the 18F-FDG PET-CT. Out of these patients, 77% (14/18) of the cases had a decrease in volume, while 11% (2/18) of them had an increase in volume on the 18F-FDG PET-CT. Additionally, 44.4% (8/18) of the patients showed a decrease by > 50 cm 3 on the 18F-FDG PET-CT. The comparison of the GTV lymph node between the 18F-FDG PET-CT and CECT revealed that the volume changed in 89% (16/18) of the patients: it decreased and increased in 50% (9/18) and 39% (7/18) on the 18F-FDG PET-CT. New nodes were identified in 27% (5/18) of the patients on the 18F-FDG PET-CT. The decrease in the GTV lymph node on the 18F-FDG PET-CT was statistically significant. The decreased target volumes made radiotherapy planning easier with improved sparing of normal tissues. CONCLUSION: GTV may either increase or decrease with the 18F-FDG PET-CT, compared to the CECT. However, the 18F-FDG PET-CT-based contouring facilitates the accurate delineation of tumour volumes, especially at margins, and detection of new lymph node volumes. The non-FDG avid nodes can be omitted to avoid elective nodal irradiation, which can spare the organs at risk and improve accurate staging and treatment.

Intracranial meningioma, mimicking brain metastasis on 18F sodium fluoride bone scan in a case of carcinoma cervix.

Bone scintigraphy (BS) is a well--established commonly used imaging modality for staging and follow--up evaluation of cancer patients. Occasionally, BS may show asymptomatic unusual extraosseous lesions in the body which may or may not be related to primary disease. We here present an interesting case of carcinoma cervix in whom 18F sodium fluoride positron emission tomography-computerized tomography (PET-CT) bone scan detected an intracranial lesion. Initially, this lesion was suspected as brain metastasis; however, later on, combined PET--CT images and contrast-enhanced CT confirmed this lesion as calcified falcine meningioma in the right posterior parietal region.