Padma Subramanyam

Dacryoscintigraphy: an effective tool in the evaluation of postoperative epiphora.

Background and aimDacryoscintigraphy is a grossly underutilized nuclear medicine procedure for assessing the patency of nasolacrimal ducts. It is an alternate noninvasive modality requiring no added expertise when compared with dacryocystography, an invasive radiological counterpart. Dacryocystorhinostomy (DCR) is a surgical procedure in which a patent rhinostomy is made so that a low-pressure lacrimal bypass system is created, thus relieving epiphora, dacryocystitis or mucocele. DCR has been accepted as a highly successful procedure in the management of epiphora from nasolacrimal duct obstruction; however, adverse local effects can reproduce epiphora. This study highlights the utility and simplicity of dacryoscintigraphy in the postoperative setting of DCR, apart from showcasing its high sensitivity and accuracy in localizing the sites of lacrimal drainage obstruction. Materials and methodsFifty-five postoperative patients of DCR were screened. Ten volunteers constituted the control group. One drop (10 &mgr;l) of technetium pertechnetate (99mTcO4) was instilled simultaneously in the outer canthus of both eyes (50–100 &mgr;Ci). Upright dynamic (8 min) and anterior static images of the eyes (up to 20 min) were acquired on a gamma camera fitted with a high-resolution collimator. Physiological interventions that were used in this study were eye blinking, saline intervention, and lacrimal sac massaging. ResultsOut of 40 symptomatic DCR patients, 22 had complete obstruction at the presac level and 18 patients had partial obstruction. Quantitative parameters like tear transit time and lacrimal sac half-life were also calculated. After massage of the lacrimal sac, progression of the tracer was observed in five patients. Premassage and postmassage tear column measurements showed a relative increase of 30.1%. Massage of eight clinically normal ducts showed a relative increase of 2.4% (P=0.06). Statistical analysis using the Fisher test shows very significant concordance between clinical symptoms and dacryoscintigraphy findings in postoperative DCR patients (P<0.0001). The modified McNemar’s pair test did not show statistically significant differences between dacryoscintigraphy and the syringing irrigation test. ConclusionDacryoscintigraphy is a simple and easy-to-perform investigation providing high sensitivity in epiphora detection in patients after DCR. Interventions play a role in further enhancing the sensitivity of the technique. This study demonstrates the utility of dacryoscintigraphy in detecting subclinical and partial lacrimal duct obstruction with good patient compliance. It provides an easy and effective way of screening families, enabling an early diagnosis. During imaging, a high-resolution collimator is found to be an efficient substitute for the conventional pinhole collimator.

A Gluten-Free Vegan Meal for Gastric Emptying Scintigraphy: Establishment of Reference Values and Its Utilization in the Evaluation of Diabetic Gastroparesis

Purpose The aim of this study was to describe the preparation of radiolabeled idli (savory cake) meal for use as an alternate to the egg white sandwich (EWS) meal in gastric emptying scintigraphy (GES). Furthermore, the aim of this study was to establish normal emptying rates for this meal and present our experience in using it in the evaluation of diabetic gastroparesis. Patients and Methods The meal was prepared using a universally available packaged mix labeled with 1 mCi 99mTc sulfur colloid, and the stability of labeling was tested up to 4 hours in simulated gastric fluid. One hundred thirteen healthy volunteers (aged 20–78 years; 54 women, 59 men) underwent GES study using the idli meal. Gastric retention at one-half, 1, 2, and 4 hours after ingestion of the meal was estimated, and the normal limits were set using the fifth and 95th percentile values at each period. Having established its normal emptying rates, the idli meal was further used to evaluate 70 patients suspected with diabetic gastroparesis. Results The idli meal, with a calorific value ≈282 kcal, has a relatively higher fat content (8% of total mass) than EWS. More than 96% of 99mTc sulfur colloid remained bound to the meal after 4 hours suspension in simulated gastric fluid. Gastric retention greater than 30% and greater than 6% at 2 hours and 4 hours, respectively, indicated delayed gastric emptying, whereas retention less than 30% at 1 hour suggested rapid emptying. Among patients suspected with diabetic gastroparesis, delayed gastric emptying was identified in 76%, and rapid emptying was seen in 4.2%. Conclusions Radiolabeled idli meal is a good alternative to EWS meal for routine GES, especially among patients with specific dietary restrictions.

Tc-99m macro aggregated albumin scintigraphy - indications other than pulmonary embolism: A pictorial essay

Introduction: Tc-99m macro aggregated albumin (MAA) is synonymous for lung perfusion scintigraphy and is part of the study in the evaluation of pulmonary thromboembolism. We wanted to highlight the utilities of Tc-99m MAA other than pulmonary embolism as a pictorial assay. Materials and Methods: Patients referred for Tc-99m MAA scintigraphy under various indications were included in this pictorial essay. Commercially available TechneScan LyoMAA cold kit from Mallinckrodt Medical B.V., Holland was used. Acquisition protocols for different indications are described in this article. Different clinical indications (e.g., pulmonary artery stenosis, hepatopulmonary syndrome, FEV1 calculation in lung surgery planning, selective internal radiation therapy planning, venography for deep venous thrombosis, left to right cardiac shunts, etc.) where Tc-99m MAA scintigraphy was asked for; how it helped in different clinical scenarios and how it can be used clinically is explained with unique and interesting case examples and images. We also reviewed the literature to look for certain remote indications of MAA imaging for the sake of completion like – (shunt scintigraphy, peritoneopleural communication, etc.) Conclusion: Tc-99m MAA is a very useful radiopharmaceutical, which can be used for many other indications apart from the commonly used indication of lung perfusion scan in pulmonary embolism. It can provide useful clinical information in other indications, which we try to highlight in this article.

Scintigraphic assessment of patellar vascularity in total knee replacement surgeries following lateral release

For a total knee replacement (TKR) to function well, the patella must track centrally in the trochlear groove. Lateral retinacular release (LR) is performed as an integral step in TKR to avoid maltracking. Patellar resurfacing and infra patellar fat pad excision are other small surgical procedures performed during TKR that can also easily deprive the patella of its vascularity. A three phase bone scan helps in the assessment of patellar vascularity. Literature review reveals a variable association (10-56%) of LR and patellar hypovascularity in Caucasians. Objective: LR release done in TKR is known to compromise patellar viability, while its extent and severity is still debated. Our prospective study was undertaken to evaluate the effects of LR on patella along with other variables like patellar resurfacement, fat pad excision, patelloplasty on knees by 99mTechnetium labeled methylene diphosphonate (99mTc MDP) three phase bone scintigraphy (TBS). Materials and Methods: 45 TKRs were done between Jan 05 and Jan 06. Of them, 15 patients (21 knees) of primary TKR were considered prospectively. Patients undergoing uni/bilateral TKR due to symptomatic knee osteoarthritis were only selected for this study. Pre- and immediate postoperative TBS was done with modified positioning of knee joints (adducted, externally rotated and flexed to 30°) to visualize patellae away from knee joint, which otherwise gets superimposed on the femoral condyles. A follow-up TBS at 8-10 weeks was done in patients showing immediate post-op patellar hypovascularity. Results: 12/21 knees (57%) needed LR. Of these 12 knees, 8 (66%) showed hypovascularity; whereas 9 knees with no LR, 1 knee showed hypovascularity. All 9 knees (8 post LR+1 without LR) with hypovascularity underwent TBS again at 8-10 weeks and were found to show improvement in their vascularity status in all cases. Conclusion: Our study showed a higher incidence of LR in our population (57%). Association of LR and patellar ischemia was significant, about 16 times the risk. MDP bone scintigraphy is the only objective tool to quantify patellar vascularity. Overall 42.8% knees post-TKR had a transient patellar ischemia, and 38% of them were following LR. All of them recovered at 8-10 weeks postoperatively.

Lymphoscintigraphy in Unilateral Lower Limb and Scrotal Lymphedema Caused by Filariasis

Lymphedema is the edema that results from chronic lymphatic insufficiency. Lymphatic filariasis is caused by the filarial nematodes Wuchereria bancrofti, Brugia malayi, and Brugia timori. Lymphatic filariasis is common in tropical and subtropical regions. Early diagnosis and prompt therapy can be implemented using lymphoscintigraphy. Our patient is a 15-year-old boy presenting with a 3-month history of hydrocele. The patient was referred to us to rule out any lower limb lymphatic obstruction as the patient is from an endemic area. Tc Sulfur colloid (filtered) lymphoscintigraphy showed abnormal tracer collection in the scrotum and penis. There is associated dermal backflow or stasis in the left thigh region extending just above the knee, suggesting partial obstruction of left inguinal lymphatic channels.

Isolated skeletal muscle metastatic deposit in a patient with micropapillary carcinoma thyroid identified by 18F FDG PET CT.

Micropapillary carcinoma of thyroid is said to be low risk differentiated thyroid malignancy with excellent prognosis. We report the identification of an isolated FDG avid muscle deposit in a treated case of micropapillary carcinoma of the right lobe and widely invasive follicular carcinoma of the left lobe thyroid gland. Patient was found to have an elevated thyroglobulin level with negative iodine scan (TENIS syndrome) on follow up at 6 months. An 18F FDG PET CT (18 fluorine-fluorodeoxyglucose positron emission computed tomography) whole body study revealed a solitary FDG avid deltoid muscle deposit which was histopathologically confirmed to be metastatic papillary carcinoma. While follicular carcinoma is known to have distant metastases, this may be the first reported case of solitary skeletal metastases from micropapillary carcinoma of thyroid and probably the second reported skeletal muscle deposit from DTC detected on 18F FDG PET CT done following elevated thyroglobulin level and negative 131 iodine WB scan (TENIS). This case also assumes importance because it demonstrates possibility of metastases even from a micropapillary carcinoma in contrast to American Thyroid Association guidelines (2009) which suggests that micropapillary carcinoma of thyroid does not merit further treatment after a Total Thyroidectomy.

Random Synchronous Malignancy in Male Breast: A Case Report

We report here a case of a random synchronous male breast malignancy in a patient with a known base of tongue malignancy that was incidentally detected on a whole body 18-fluorine deoxyglucose positron emission tomography and computed tomography (18F-FDG PET/CT). Patient was referred to us for PET/CT staging and radiotherapy planning for a poorly differentiated squamous cell carcinoma of base of tongue. Histopathologically, the incidentally detected breast lesion was proven to be an invasive ductal carcinoma. 18F-FDG PET/CT being a whole body imaging modality is known to detect a considerable number of synchronous primaries. Synchronous malignancies in the head and neck area and the upper aerodigestive tract are well established. However, synchronous malignancy in male breast is reportedly uncommon. Our case is unique for the fact that a random synchronous dual malignancy of base of tongue and breast in a male patient was detected during a whole body 18F-FDG PET/CT imaging.

Feasibility study of axillary reverse mapping lymphoscintigraphy in carcinoma breast: A concept toward preventing lymphedema.

Objective: In the surgery of breast cancer, axillary reverse mapping (ARM) is the identification and preservation of arm draining lymph node (ARM node) during an axillary dissection. The assumption is that the ARM node is different from node draining breast and is unlikely to be involved even in the patients with axillary nodal metastases. If we can identify and preserve ARM node using lymphoscintigraphy; morbidity of lymphedema, as seen with axillary dissection, may be avoided. Materials and Methods: Pathologically proven 50 breast cancer patients undergoing initial surgery (cTx-4, cN0-2, and Mx-0) were included in this study. Less than 37 MBq, 0.5 ml in equally divided doses of filtered 99mTc sulfur colloid was injected intradermally into the second and third web spaces. ARM nodes in the axilla were identified with the help of Gamma Probe intraoperatively; however, their location was noted with the reference to specific anatomical landmarks and sent for histopathological examination after excision. Results: The ARM node was successfully identified in 47/50 cases (sensitivity - 94%). In 40 out of 47 cases (85%), the location of the ARM node was found to lateral to the subscapular pedicle, above the second intercostobrachial nerve and just below the axillary vein. Of the 47 patients in whom ARM node/s were identified, metastasis was noted in 5 of them (10%). Four out of these 5 patients had the pN3 disease. Conclusion: ARM node exists, and it is feasible to identify ARM node using radio isotope technique with an excellent sensitivity. ARM node seems to have a fairly constant location in more than 80% cases. It is involved with metastasis (10% cases) only when there are multiple lymph nodal metastases in the axilla.

Zosteriform cutaneous metastases from an occult primary malignancy of lung identified by whole-body FDG PETCT imaging

Cutaneous metastasis may be the first evidence of internal malignancy or a sign of recurrence of malignancy and is considered a grave prognostic sign. There are various morphological variants of cutaneous metastases, with the most common being solitary to multiple erythematous infiltrating papules and nodules and the rarer variants being carcinoma erysipeloides, carcinoma en cuirasse, carcinoma telangiectaticum, alopecia neoplastica, metastasis to the inframammary crease, and zosteriform pattern. FDG PETCT is an established imaging modality in the identification of an unknown primary malignancy and also has an important role in the therapeutic decision-making.

Dual Time Point 18F-FDG PET/CT Imaging Identifies Bilateral Renal Tuberculosis in an Immunocompromised Patient with an Unknown Primary Malignancy

18F-FDG PET/CT imaging is an established imaging modality for cancer staging and response assessment. Its role in identifying infective and inflammatory pathologies from malignancy is debated. Dual time - point imaging is a refined technique used to overcome this interpretational dilemma. We present a 59 year old male with an unknown primary malignancy who was referred for a 18F-FDG PET/CT imaging. Images revealed primary lung malignancy with co existing bilateral renal tuberculosis which otherwise would have gone amiss or would have been considered as metastases.