The primary clinical application of (18)F FDG PET/CT ((18)Fluorine labeled flurodeoxyglucose positron emission tomography/computed tomography) in differentiated thyroid carcinoma is in the identification of active disease in thyroglobulin (Tg) positive (>10 ng/ml), whole body iodine scan negative patients. The impact of FDG PET/CT in diagnosis, surveillance, cure, and progression-free survival of differentiated thyroid carcinoma patients remains to be seen. Five main indications of FDG PET/CT in thyroid cancer have been recommended by revised American thyroid association guidelines 2009. This review aims to provide a complete picture of PET imaging in thyroid malignancies and enumerates each indication with literature review. This review also highlights recent advances in targeted molecular imaging. Currently differentiated thyroid cancer is best imaged using conventional single photon emission computed tomography-based radioiodine tracers ((123)I/(131)I). Although the utility of FDG PET in well differentiated thyroid cancer patients who are iodine negative but with raised Tg is well established, evidence is emerging on the advantages of FDG PET/CT in other histological types of thyroid malignancy, such as Hurthle cell, medullary, and the anaplastic malignancies. Novel PET radiotracers, such as (124)Iodine ((124)I), (18)F-DOPA (3,4-dihydroxy-L-phenylalanine), and (68)Ga-DOTA peptides are revolutionizing the way thyroid malignancies are imaged. Newer concepts on targeted molecular imaging and theranostics are ushering in new possibilities for imaging and treating thyroid cancer.

Introduction:Differentiated thyroid carcinoma (DTC) is the most common pathological type of thyroid carcinoma, which includes papillary and follicular subtypes. DTC is usually indolent, characterized by good prognosis, and long-term survival. Total thyroidectomy is the mainstay of treatment in DTC which is followed by diagnostic whole body 131I (WBI) scan. Like other primary malignancies of the head and neck, DTC follows a consistent pattern of spread in the cervical LNs. The central compartment, level VI and VII, is the first sentinel node followed by spread to the lateral compartments levels II–V, followed by the contralateral side. Inspite of nodal involvement, DTC usually have a favourable outcome. Presence of extrapulmonary distant metastases could predict a poor prognosis for high-dose 131I therapy. However, distant metastasis occurs often as a grave event and mortality rates vary depending on metastatic sites.Aim and Objectives:A range of rare 131I concentrating DTC deposits in sella, orbit, choroid, skeletal muscles, liver, skin, costochondral soft tissue, pancreas and kidney, and a few benign 131I concentrating sites are being depicted.Materials and Methods:Metastatic sites from DTC can be easily identified by performing a whole body 131I (WBI) scan along with a stimulated thyroglobulin (Tg) estimation (TSH >30 uIU/ml). Apart from thyroid and thyroid-related diseases, certain benign non-thyroidal pathologies can concentrate radioiodine (131I). From 13,000 of our patients who underwent radioiodine scan for thyroid cancer, we have selected a few cases of 131I concentrating benign and malignant lesions for illustration.Results:Out of 13000 DTC patients who underwent whole body 131I scintigraphy in our department from Jan 2007 till Mar 2018, 25 patients revealed benign sites of 131I uptake. 61 % patients had residual thyroid tissue with or without associated nodal involvement. Remaining patients had distant metastases. Rare sites of functioning thyroid metastases and benign sites of I 131 uptake have been selected for illustration.Conclusion:Apart from the WBI (two-dimensional, planar) images, single-photon emission computed tomography-computed tomography (SPECT-CT) has been incremental in localizing benign lesions which greatly depends on their location. This pictorial review highlights the need to create an awareness to detect metastatic deposits of DTC at unexpected sites. Otherwise patients will need further investigation to rule out unsuspected sites of functioning distant metastases.

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.

Radiolabeled idli meal is a good alternative to EWS meal for routine GES, especially among patients with specific dietary restrictions.

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.

Baastrup's disease is a benign condition, which presents as chronic low back pain. It is also known as “kissing spine syndrome” and refers to close approximation of adjacent spinous processes producing inflammation and back pain. This condition is often misdiagnosed, resulting in incorrect treatment and persistence of symptoms. Diagnosis of Baastrup's disease is verified with clinical examination and imaging studies. Conventionally, clinicians resort to magnetic resonance imaging (MRI) of spine rather than X-ray or computed tomography (CT) in the evaluation of back pain. MRI can additionally identify flattening, sclerosis, enlargement, cystic lesions, and bone edema at the articulating surfaces of the two affected spinous processes. Studies have reported that 18Fluorine fluorodeoxyglucose-positron emission tomography/CT (FDG-PET/CT) can detect a bursitis or an inflammation as a form of stress reaction despite a negative MRI and 99mTc Methylene diphosphonate (MDP) bone scan. PET/CT is usually not a recommended investigation for this condition. However, this case report highlights the benefit of FDG-PET/CT in identifying the site of inflammatory pathology. It is also known to identify the exact site of inflammation where steroid or local anesthetic injection can be administered to alleviate pain, especially in patients with multilevel vertebral involvement.

Dacryoscintigraphy 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.

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.