FDG PET and PET/CT: EANM procedure guidelines for tumour PET imaging: version 1.0. Eur J Nucl Med Mol Imaging. 2010;37:181-200. [PMID: 19915839 PMCID: PMC2886119 DOI: 10.1007/s00259-010-1459-4]

Can [18F]F-FDG PET/CT be used to assess the pre-operative extent of peritoneal carcinomatosis in patients with colorectal cancer?

PURPOSE

To evaluate whether PET/CT could be used to assess the extent of colorectal peritoneal metastases.

METHODS

All patients who underwent a PET/CT scan before a CRS-HIPEC procedure between January 1, 2010 and December 31, 2013 were retrospectively included (n = 35). Two nuclear medicine physicians (observer 1 and observer 2) separately reviewed the scans on intraperitoneal abnormalities. A simplified PCI was used to compare the extent of rPCI versus sPCI.

RESULTS

Included patients had a median age of 60.6 years. Histology of primary tumors were 51.5% adenocarcinomas, 37.1% mucinous adenocarcinoma, and 11.4% SRCC. Median sPCI was 9.5 (5.0-11.8) and median rPCI was 5.0 (3.0-7.0) for observer 1 and 4.0 (3.0-6.0) for observer 2 (p = 0.02 and p = 0.01, respectively). When compared to the surgical data, PET/CT showed a poor correlation for assessing the extent of PC for both adenocarcinoma (observer 1 rho - 0.17, p = 0.51 and observer 2 rho 0.13, p = 0.61) as well as mucinous carcinoma or SRCC (observer 1 rho 0.44, p = 0.08 and observer 2 rho 0.38, p = 0.14).

CONCLUSION

PET/CT underestimates the extent of PC during surgery in both mucinous and non-mucinous CRC and is not recommended for intraperitoneal tumor scoring.

Comparison of 18F-NaF PET/CT and 18F-FDG PET/CT for Detection of Skull-Base Invasion and Osseous Metastases in Nasopharyngeal Carcinoma

Our study aimed at comparing the diagnostic value of 18F-NaF positron emission tomography-computed tomography (PET/CT) and 18F-fluorodeoxyglucose (FDG) PET/CT for detection of skull-base invasion and osseous metastases in patients with nasopharyngeal carcinoma (NPC). Our study retrospectively analyzed 45 patients with pathologically proven NPC. They all underwent both 18F-NaF PET/CT and 18F-FDG PET/CT within a 7-day interval. Bone metastases were confirmed by follow-up using PET/CT, enhance-contrast computed tomography (CT), and magnetic resonance image (MRI). These two examinations were compared using per-patient-based analysis and per-lesion-based analysis. 18F-NaF PET/CT detected 27 patients with skull-base invasion, whereas 18F-FDG PET/CT detected 17 patients. 18F-NaF PET/CT and 18F-FDG PET/CT differed significantly in diagnosing skull-base invasion (p=0.02) and sensitivity (p=0.008). The sensitivity, specificity, and agreement rate of 18F-NaF PET/CT for detecting bone metastatic lesions were 98.3%, 65.7%, and 92.9%, respectively; these values were 42.9%, 97.1%, and 51.9%, respectively, for 18F-FDG PET/CT. 18F-NaF PET/CT and 18F-FDG PET/CT differed significantly in the number of osseous metastases detected (t=2.45, p=0.18) sensitivity (p < 0.0001) and specificity (p=0.003). In patients with nasopharyngeal carcinoma, 18F-NaF PET/CT assessed invasion of the skull base better and detected more osseous metastases than 18F-FDG PET/CT.

Carcinoma of unknown primary and paraneoplastic dermatomyositis

Dermatomyositis is known to be associated with neoplastic disorders, however the presentation of carcinoma of unknown primary as dermatomyositis is rare. We describe a case index of 50-year-old female who presented with enlarged inguinal lymph nodes accompanied with symmetric proximal muscle weakness and erythematous plaques. Conventional basic work-up did not reveal the diagnosis, however, positron emission tomography-computed tomography and re-staining of the pathology specimen suggested the ovaries as the primary site. Chemotherapy including carboplatin paclitaxel and bevacizumab led to complete response of disease and improvement in the dermatomyositis. The present case emphasizes the importance of a thorough directed evaluation for the underlying cancer in patients with carcinoma of unknown primary presenting as dermatomyositis. We further provide an up-to-date detailed review of published data describing these clinical entities.