Sumbul Zaheer

Use of Ga-68 DOTATATE PET/CT to confirm portal vein tumor thrombosis in a patient with pancreatic neuroendocrine tumor.

A 37-year-old man complained of increasing severity and frequency of abdominal pain over a 2-year period. Initial contrast-enhanced computed tomography of the abdomen demonstrated diffuse enlargement of the pancreas associated with a filling defect in the portal vein, splenomegaly with wedge-shaped peripheral splenic hypodensities and multiple hepatic hypodensities. Findings were suggestive of a pancreatic malignancy complicated by hepatic metastases, splenic infarcts, and portal vein thrombosis. We describe the use of gallium-68 DOTA-DPhe1, Tyr3-octreotate positron emission tomography/computed tomography (Ga-68 DOTATATE PET/CT) in confirming the diagnosis of a pancreatic neuroendocrine tumor with portal vein tumor thrombosis.

Usefulness of F-18 fluorodeoxyglucose positron emission tomography/computed tomography in a case of choriocarcinoma presenting as pulmonary embolism.

This case demonstrates the utility of performing F-18 fluorodeoxyglucose positron emission tomography/computed tomography for the investigation of an unresolving pulmonary embolus, where early diagnosis of tumor thrombus or primary neoplastic conditions of the pulmonary artery may be made. Choriocarcinoma presenting within the pulmonary artery is rare although a literature review shows that a number of important differential diagnoses of hypermetabolic pulmonary lesions should be kept in mind.

Recurrent Dermatofibrosarcoma Protuberans of the Shoulder with Rare Distant Abdominal Metastasis detected by Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography (FDG-PET/CT).

A 56-year-old male patient with a rare dermatofibrosarcoma protuberans and fibrosarcomatous change (DFSPFS) presented with a solitary fluorodeoxyglucose (FDG)-avid tumour with no evidence of metastasis in the left upper extremity [Figure 1A]. This initial presentation was treated with wide excision, and then again at its recurrence 8 months later. At admission, the patient had symptoms of gastritis and underwent an oesophago-gastroduodenoscopy, which was normal. Almost 3 years after the initial presentation, the patient presented with a retroperitoneal mass measuring 1.4 x 0.8 cm. Investigation revealed the tumour, which was avid on FDG-PET/CT (standardised uptake value [SUV] max 11.3) and new compared to the previous study [Figure 2B]. Mild FDG uptake was also noted in a new pulmonary nodule (SUV max 1.9) and appeared malignant [Figure 3B]. Figure 4 shows the maximum intensity projection (MIP) images from the two studies. The retroperitoneal tumour was found to be dermatofibrosarcoma protuberans with extensive fibrosarcomatous transformation, histology grade 3 [Figures 5A and ​and5B5B]. Figure 1: Fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scans at the same trans-axial levels, showing mildly FDG-avid local recurrence in the shoulder (A), with no lesion subsequently identified in the same region (B). Figure 2: Fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scan at the same trans-axial level comparing the two scans at the time of local recurrence in 2006, when there was no retro-peritoneal lesion (A) and subsequently at ... Figure 3: Fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scan at the same trans-axial level comparing the two scans at the time of local recurrence in 2006 when there was no pulmonary lesion (A) and subsequently at the time ... Figure 4: Maximum intensity projection of the fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scans at the time of the first presentation in 2006 with (A) a mildly FDG-avid local recurrence, and (B) subsequently, in 2009, with ... Figure 5: (A) Pathology slide of low-powered view of fibrosarcoma with herring-bone pattern; (B) Pathology slide showing areas of viable tumor fascicles with adjacent necrosis DFSP is a rare cutaneous tumour of low malignant grade characterised by a pattern of slow, infiltrative growth and a marked tendency to recur locally after surgical excision.1 DFSP is commonly found on the trunk (42–72%), occasionally in the proximal extremities (16–30%), and infrequently above the neck (10–16%).7 Rare distant metastases (in less than 5% of cases) may occur many years after the onset of disease and are limited mostly to the lungs, followed by regional lymph nodes, while the visceral organs and bones are rarely affected.2 Metastases are more likely with repeated incomplete surgical excisions and by tumour de-differentiation to higher grades.6 Metastases are associated with local recurrence and poor prognosis. The 5-year survival rate is estimated at 99.2%.7 DFSP is a fibrosarcoma originating from dermal fibroblasts.6 The genetic abnormalities in DFSP include a supernumerary ring chromosome related to the low amplification of sequences of chromosomes 17 and 22 which is a form of balanced reciprocal translocation.8 This rearrangement will cause fusion of alpha chain type A (COL1A1) located on 17q22 to the platelet-derived growth factor beta (PDGFB) located on 22q13. As a result, the COL1A1-PDGFB gene formation will result in up regulation of PDGFB expression, resulting in continuous autocrine activation of PDGF receptor beta (PDGFR-B) and propagation of the mitotic signal by formation of autocrine and paracrine loops.9 These transformed cells are inhibited by the tyrosine kinase inhibitor imatinib mesylate with reported cases of response often documented with FDG.10 The surgical objective in DFSP is complete tumour excision with maximal normal tissue preservation. Hence, a wide local excision with lateral margins of at least 3 cm and including the underlying fascia is recommended. In addition, micrographic controlled excision (MCE) showed favourable outcomes in treating DFSP.6 FDG-PET/CT findings in a case of recurrence of dermatofibrosarcoma in the surgical scar have been reported.3 FDG-PET/CT has also been used to monitor response to imatinib mesylate in 2 reported cases of unresectable metastatic DFSP, with a decrease in tumour uptake of FDG after treatment documented in both cases.4–5 In the former case, this decrease in uptake coincided with clinical improvement as early as 2 weeks after commencement of the therapy.4 In contrast to our case, where a FDG-avid pulmonary lesion was noted on PET/CT, a previous case reported a pulmonary nodule which was noted on CT but not on FDG-PET. It was thought this may have been due to the size (8 mm). A case has also been reported where DFSP response to imatinib was noted on FDG-PET but not on CT.10 This is similar to findings in other malignancies. DFSP is a rare cutaneous tumour of low malignant grade. FDG-PET/CT has been reported to be useful in DFSP imaging for delineating disease extent, both in staging and recurrence, which can be useful in planning surgery. FDG has also been documented as assessing DFSP response to imatinib, showing response when none was noted on CT. Given the rarity of the disease there are no large studies to date but the existing data appears promising. We suggest that FDG PET/CT be considered as an important component of the treatment plan of patients with DFSP.

The incidence and sites of Nasopharyngeal carcinoma (NPC) metastases on FDG PET/CT scans

INTRODUCTION The only investigation to determine if a whole body FDG PET/CT scan is helpful in the evaluation of NPC is a study from Stanford. In this study, 26 patients with whole body PET/CT, were evaluated for lesions below adrenals and showed that 7.7% of distant metastases were below adrenals. Our study comparing distant metastases below diaphragm with Stanford study to evaluate the need for whole body PET/CT. MATERIAL AND METHODS Reports of NPC patients in Singapore General Hospital were reviewed. The lesions were analyzed for total number and number below diaphragm. The lesions below the diaphragm were further analyzed if they were solitary or involved multiple areas and if any additional lesions were above diaphragm. RESULTS 717 reports were included in final analysis. The number of FDG avid lesions in these reports was 709. Distant metastases represented 352 of the 709 lesions. The number of lesions below diaphragm was 152, of the lesions below diaphragm only 16 of lesions have no co-existing distant metastases above diaphragm. From these lesions, there were only 12 solitary lesions. The other 4 has concurrent metastases but all localized below diaphragm. CONCLUSION Compared to Stanford study, number of reports is more representative in this study and the yield is much lower (7.7% versus 2.26%). From the results of our study we can consider limiting the scan area from vertex to below diaphragm. However, the symptoms and clinical presentation of the patient will further direct the requesting physician in the area to be imaged.

18F-fluorodeoxyglucose-positron emission tomography/computed tomography imaging of metastatic nasopharyngeal cancer with emphasis on the distribution of bone metastases

Distant metastases change the prognosis of patients with nasopharyngeal carcinoma (NPC) which most commonly metastasizes to the bone. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is reported as useful in imaging NPC metastases. Our study assesses the incidence and distribution of bone metastases detected by 18F-FDG PET/CT in NPC. 717 18F-FDG PET/CT scan reports of histologically proven NPC patients imaged in Singapore General Hospital, Singapore, between 2003 and 2009 were reviewed for the total number of metastases (scanned from vertex to mid-thigh) and analyzed for distribution. Of the 709 FDG avid metastases in these reports, 357/709 (50.35%) were locoregional nodal metastasis and 352/709 (49.65%) were distant metastases of which 192/709 (27.08%) of total metastases and 54.54% of distant metastases (192/352) were in the bones. The majority of the bone lesions 125/192 (65.1%) were in the axial skeleton with 109/192 (56.77%) in the lower skeleton (thoracolumbar spine, sacrum, and pelvis). The incidence of bone metastases in our study (27.08%) was higher than that reported in other studies, for example, 15% by Liu et al. and 11% (230 patients) by Caglar et al. Bone metastases have been reported in the femurs and the feet and as such some metastases may have been outside the field of view of the scans. In our study, 27% of FDG avid NPC metastases are in the bones.

Gender, Race, and Age at Diagnosis as Risk Factors for Metastasis or Recurrence among 1,657 Thyroid Cancer Patients Treated with Radioiodine across 40 Years in Singapore

Background: To obtain descriptive data on Singaporean thyroid cancer patients treated with radioiodine and to assess gender, race, and age at diagnosis as risk factors for metastasis or recurrence. Methods: This is a retrospective study of all thyroid cancer patients treated with radioiodine of any prescribed activity at our institution. Data collected included: age at diagnosis, gender, race, histopathological type, duration of follow-up, and metastasis at diagnosis (locoregional or distant) or recurrence at any time. Gender, race, and age at diagnosis were analyzed for possible associations with metastasis or recurrence. Results: A total of 1,657 thyroid cancer patients were treated with radioiodine across a 40-year period; mean follow-up 6.4 ± 6.9 years (median 4.2 years). 656 (39.6%) patients had metastasis or recurrence over the duration of their follow-up. Male gender (odds ratio (OR) 1.38; p = 0.006), Malay race (OR 1.71; p < 0.0001), and age at diagnosis of > 46 years (OR 1.31; p = 0.007) were significantly associated with metastasis or recurrence. Conclusion: Male gender, Malay race, and age at diagnosis of > 46 years were significant risk factors for metastasis or recurrence in Singaporean thyroid cancer patients treated with radioiodine.