Sarcoma of the thyroid co-occurrence with Carcinoma (Carcinosarcoma)

Accurate imaging of patients with possible recurrent colorectal cancer (CRC) is vital, as it is now clear that curative surgery is still possible for a proportion of patients with metastatic disease. Follow-up is usually performed with carcinoembryonic antigen (CEA) level, computerized tomography (CT) and other conventional imaging techniques, but in the last few years, functional imaging using integrated positron emission tomography and CT (PET/CT) is being used increasingly to identify recurrent disease. To evaluate the usefulness of integrated PET/CT in the follow-up of postoperative CRC patients with rising CEA level. Seventy-three histopathologically proven patients with postoperative CRC having undergone CT of chest and abdomen were subjected to PET/CT imaging. Whole-body PET/CT imaging (base of skull to mid thigh region) was performed in all patients. These patients were grouped into various categories depending on CEA level. Of the total 73 patients, 22 had CEA levels within normal limits (<3 ng/ml). Among the remaining 51 patients, CT showed recurrence in 23 (45%) patients, whereas PET/CT was positive in 36 (71%) patients. In group 1 (CEA 3-5 ng/ml), CT was positive in four of 13 (30%) patients and PET/CT was positive in seven of 13 (53%) patients, in group 2 (CEA 5-10 ng/ml) CT was positive in three of nine (33%) patients and PET/CT was positive in six of nine (67%) patients, in group 3 (CEA 10-20 ng/ml) CT was positive in five of 11 (45%) patients and PET/CT was positive in seven of 11(63%) patients, in group 4 (CEA 20-50 ng/ml) CT was positive in five of nine (55%) patients and PET/CT was positive in seven of nine (77%) patients and in group 5 (CEA >50 ng/ml) CT was positive in six of nine (67%) patients and PET/CT was positive in nine of nine (100%) patients. Among 23 patients in whom both CT and PET/CT were positive, PET/CT showed extra lesions in 17 (73%) patients and changed the management in 11 (47%) patients. PET was negative in four patients with positive findings on CT, thereby changing the management. Of the total of 51 patients, PET/CT changed the management in 28 (55%) patients. This study shows an overall detection rate of 71% for PET/CT compared with 55% for CT in postoperative CRC patients with increasing CEA. PET/CT changes the management in half of the patients, highlighting the superior role of fluorodeoxyglucose PET/CT scan over CT scan.

Carcinoembryonic antigen (CEA) is a tumor marker that is mostly used to track patients with colorectal cancer (CRC). CEA is an indirect tumor marker that can be useful in both malignant and benign diseases. We presented the case of a 49-year-old man who had been monitored for a lower rectal adenocarcinoma since 2010. In 2010, he had an abdominoperineal resection. Previously completed both neoadjuvant and adjuvant chemo-radiotherapy. In 2019, he was planned to undergo parastomal hernia (PS) repair, but studies have shown elevated CEA levels. The CEA concentration was 27.6 ng/ml. Although there were no signs of recurrence, positron emission tomography (PET) and computed tomography (PET/CT) revealed considerable uptake in the left lobar thyroid. Papillary thyroid carcinoma (PCT) was found on fine needle aspiration cytology (FNAc). He underwent total thyroidectomy and CEA level reached the baseline after thyroidectomy.

555 18F-FDG PET/CT as a new imaging modality for diagnosis of cardiac device infections (PET-ID)

Prognostic Value of PET/CT Performed Day +100 Post Autologous Stem Cell Transplantation in Multiple Myeloma: Real-World Single Center Experience

Selective Application of a Test Based on Risk: Using Limited Resources Wisely

Objective:Positron emission tomography and computed tomography (PET/CT) has become an important part of staging and treatment evaluation algorithms of lymphoma. We aimed to compare the results of PET/CT with bone marrow biopsy (BMB) with respect to bone marrow involvement (BMI) in patients with Hodgkin’s lymphoma (HL) and aggressive non-Hodgkin’s lymphoma (aNHL).Materials and Methods:The medical files of a total of 297 patients diagnosed with HL or aNHL and followed at the hematology clinics of 3 major hospitals in İstanbul between 2008 and 2012 were screened retrospectively and 161 patients with classical HL and aNHL were included in the study. The patients were referred for PET/CT and BMB at the initial staging. BMB was performed as the reference standard for the evaluation of BMI. Results:There were 61 (38%) HL and 100 (62%) aNHL patients. Concordant results were revealed between PET/CT and BMB in 126 patients (78%) (52 HL, 74 aNHL), 20 with positive PET/CT and BMB results and 106 with negative PET/CT and BMB results. There were discordant results in 35 patients (9 HL, 26 aNHL), 16 of them with positive BMB and negative PET/CT results and 19 of them with negative BMB and positive PET/CT results.Conclusion:We observed that PET/CT is effective to detect BMI, despite it alone not being sufficient to evaluate BMI in HL and aNHL. Bone marrow trephine biopsy and PET/CT should be considered as mutually complementary methods for detection of BMI in patients with lymphoma. In suspected focal involvement, combining biopsy and PET/CT might improve staging results.

P-0273 Hepatic Metastasis and Reccurence of Colorectal Cancer Assesment by 18FDG PET/CT

Comparison of the diagnostic validity of positron emission tomography (PET) alone with integrated PET and CT (PET/CT) in the search for occult primary tumors in patients with cancer of unknown primary (CUP) site in the head and neck. Thirty-nine consecutive patients with clinical CUP were investigated with PET and 38 patients with PET/CT. After initial diagnostic panendoscopy and histological confirmation of the cervical lymph node metastasis, either PET or PET/CT scanning was performed. Integrated PET/CT had a significantly higher overall detection rate than dedicated PET alone (55.2% vs 30.8%; p = .039) and positive prediction rate (93.3% vs 46.1%; p = .01). Integrated PET/CT showed to be superior to PET in the detection of the primary site of clinically occult tumors in CUP syndrome. However, a negative result should still be investigated further by means of panendoscopy with tonsillectomy and blind biopsies.

The Role of 18F-Fluorodeoxyglucose Positron Emission Tomography and CT (PET-CT) for the Diagnosis of Infections in Hemato-Oncological Patients with Persistent Neutropenia and Fever.

To determine the clinicopathological and imaging features in 18F-fluoro-2-deoxyglucose (18F-FDG) positron emission tomography and computed tomography (PET/CT) for paraganglioma of testis, and to increase the diagnostic accuracy. Methods: A case of paraganglioma of testis with multiple lymph node and lung metastasis were reported. PET/CT and pathological findings in the case were retrospectively analyzed. Results: The patient presented with high blood pressure, high level of catecholamine, and urinary vanillylmandelic acid. The patient underwent 18F-FDG PET/CT, which showed the features including the right testis nodule with a star lesion nearby, the right spermatic cord, the lymphadenopathy of bilateral inguinal and retroperitoneum, the posterior basal segment of right lung nodule, and a lot of brown adipose tissues (BAT) in the whole body with intense FDG uptake. 18F-FDG PET/CT showed that the intense FDG uptake of the BAT disappeared after the excision of the right testis and metastasis of paraganglioma. Conclusion: PET/CT shows great value in localization diagnose, clinical staging and curative evaluation. PET/CT plays a helpful role in revealing the BAT with 18F-DG avidity in the patients with paraganglioma with elevated blood pressure, high level catecholamine, and urinary vanillylmandelic acid.

Positron Emission Tomography/Computed Tomography Imaging for the Detection of Recurrent Ovarian and Fallopian Tube Carcinoma: A Retrospective Review

The aim of our study was to assess the inter-observer variability in delineation of the gross tumour volume (GTV) of oesophageal cancer on magnetic resonance (MR) in comparison to computed tomography (CT) and positron emission tomography and CT (PET/CT). Twenty-three consecutive patients with oesophageal cancer treated with chemo-radiotherapy were enrolled. All patients had PET/CT and MR imaging in treatment position. Five observers independently delineated the GTV on CT alone, MR alone, CT with co-registered MR, PET/CT alone and MR with co-registered PET/CT. Volumes of GTV were measured per patient and imaging modality. Inter-observer agreement, expressed in generalized conformity index (CIgen), volumetric conformity index (VCI), planar conformity index (PCI) and inter-delineation distance (IDD) were calculated per patient and imaging modality. Linear mixed models were used for statistical analysis. GTV volume was significantly lower on MR (33.03 cm3) compared to CT (37.1 cm3; p = 0.002) and on PET/CT MR (35.2 cm3; p = 0.018) compared to PET/CT (39.1 cm3). The CIgen was lowest on CT (0.56) and highest on PET/CT MR (0.67). The difference in CIgen between MR (0.61) and CT was borderline significant (p = 0.048). The VCI was significantly higher on MR (0.71; p = 0.007) and on CT MR (0.71; p = 0.004) compared to CT (0.67). The PCI was significantly higher on CT MR (0.67; p = 0.031) compared to CT (0.64). The largest differences were observed in the cranio-caudal direction. The highest inter-observer agreement was found for PET/CT MR and the lowest for CT. MR could reduce the difference in delineation between observers and provide additional information about the local extent of the tumour.

This study compares intrinsically coregistered 124I positron emission tomography (PET) and CT (PET/CT) and software coregistered 124I PET and MRI (PET/MRI) images for the diagnosis and dosimetry of thyroid remnant tissues and lymph node metastases in patients with differentiated thyroid carcinoma (DTC). After thyroidectomy, 33 high-risk DTC patients (stage III or higher) received 124I PET/CT dosimetry prior to radioiodine therapy to estimate the absorbed dose to lesions and subsequently underwent a contrast-enhanced MRI examination of the neck. Images were evaluated by two experienced nuclear medicine physicians and two radiologists to identify the lesions and to categorize their presumable provenience, i.e. thyroid remnant tissue (TT), lymph node metastasis (LN) and inconclusive tissue. The categorization and dosimetry of lesions was initially performed with PET images alone (PET only). Subsequently lesions were reassessed including the CT and MRI data. The analyses were performed on a patient and on a lesion basis. Patient-based analyses showed that 26 of 33 (79%) patients had at least one lesion categorized as TT on PET only. Of these patients, 11 (42%) and 16 (62%) had a morphological correlate on CT and MRI, respectively, in at least one TT PET lesion. Twelve patients (36%) had at least one lesion classified as LN on PET only. Nine (75%) of these patients had a morphological correlate on both CT and MRI in at least one LN PET lesion. Ten patients (30%) showed at least one lesion on PET only classified as inconclusive. The classification was changed to a clear classification in two patients (two LN) by CT and in four (two TT, two LN) patients by MRI. Lesion-based analyses (n=105 PET positive lesions) resulted in categorization as TT in 61 cases (58%), 16 (26%) of which had a morphological correlate on CT and 33 (54%) on MRI. A total of 29 lesions (27%) were classified as LN on PET, 18 (62%) of which had a morphological correlate on CT and 24 (83%) on MRI. In 16 lesions (15%) PET alone allowed no definite categorization. Categorization was achieved with the aid of CT and MRI, respectively, in five (one TT, four LN) and in six (two TT, four LN) lesions. In direct comparison, 23 lesions were not discernible on CT but clearly visible on MRI, 15 of which were smaller than 10 mm and about two thirds were classified as TT. Redoing dosimetry based on the volume information from MRI for these small lesions would have changed the initial therapy regime in five patients. These patients would have received (131)I therapy with standardized activities of 3.7 GBq or 7.4 GBq instead of activities higher than 10 GBq and would have benefited from reduced radiation exposure. PET/MRI is superior to PET/CT in terms of tracing back a PET focus to a morphological correlate. For this reason PET/MRI enhances diagnostic certainty for lesions<10 mm and improves pretherapeutic lesion dosimetry in DTC.

**284** ### **Objectives** Aim of our study was to evaluate the usefulness of integrated positron emission tomography and computed tomography (PET/CT) in follow up of post operative colorectal cancer patients with raising CEA levels. ### **Methods** Thirty one histopathologically proven patients of post operative colorectal cancer were subjected to F-18 FDG PET/CT imaging. Base of skull to mid thigh imaging was performed in all patients. These patients were grouped into five categories depending upon CEA level. ### **Results** Of the total of 31 patients, CT alone demonstrated recurrence in 13(42%) patients, while PET/CT was positive in 22(71%) patients. In Group I (CEA \<5ng/ml) CT was positive in 1/5 patients and PET/CT was positive in 3/5 patients. In Group II (CEA 5-10ng/ml) CT was positive in 2/6 patients and PET/CT was positive in 4/6 patients. In Group III (CEA 10-20ng/ml) CT was positive in4/7 patients and PET/CT was positive in 5/7 patients. In Group IV (CEA 20-50ng/ml) CT was positive in 3/6 patients and PET/CT was positive in 5/6 patients. In Group V (CEA \>50ng/ml) CT was positive in 4/7 patients and PET/CT was positive in 7/7 patients. Among 13 patients in whom both CT and PET/CT were positive PET/CT demonstrated extra lesions in 10 (77%) patients and changed the management in 7 (54%) patients. Of the total of 31 patients PET/CT changed the management in 16(52%) patients. ### **Conclusions** This study demonstrates overall sensitivity of 71% for PET/CT compared to 42% for CT. PET/CT changes the management in half of the patients, highlighting the superior role of FDG PET/CT scan over CT scan

Pulmonary Adenofibroma (PAF) is a rare soft tissue tumour of the lung. It is a benign lesion, having a biphasic pattern with an admixture of epithelial and stromal components and has resemblance to fibroadenoma of the breast and adenofibroma of the female genital tract. The diagnosis can be challenging and it has to be delineated from other entities with biphasic pattern, like pulmonary hamartoma, pulmonary blastoma, intrapulmonary solitary fibrous tumour and metastases from soft tissue and visceral sarcomas, as each tumour has its own therapeutic and prognostic implications. Here, we report a case of a 73-year-old male, a known case of recurrent soft tissue sarcoma of the thigh, who presented with solitary pulmonary lesion. The patient was a non-smoker and did not have any specific respiratory complaints. On staging work-up with a Positron Emission Tomography and Computed Tomography (PET-CT), a hypermetabolic lesion was identified in the anterior segment of right upper lobe of the lung, following which he underwent right lobectomy. The tumour was a solitary lesion located near the hilum and on histology showed a biphasic pattern with scattered glandular spaces lined by columnar epithelium set in a hyalinised spindle cell stroma. The cells showed mild pleomorphism with oval to elongated nuclei and indistinct cytoplasm. On immunohistochemistry, the epithelial component showed positivity for Cytokeratin (CK), Epithelial Membrane Antigen (EMA), Thyroid Transcription Factor-1 (TTF-1) and Napsin-A and the stromal component showed positivity for Vimentin, Desmin, Smooth Muscle Actin (SMA) and H-Caldesmon (High molecular weight isoform-Caldesmon). With the given histological and immunohistochemistry findings, a diagnosis of PAF was rendered.