ABSTRACT
Introduction Rectal cancer has become a major cause of mortality worldwide. Imaging has a primary role in staging and assessing the response to therapy. MRI is superior to all other modalities in local staging of the rectal tumor and in predicting tumor response. Pelvic MRI has an undeniable role in the therapeutic management of rectal cancer, particularly for the determination of the circumferential resection margin (CRM), evaluation of sphincter invasion, and assessment of the extramural vascular invasion. Post-chemoradiotherapy (CRT) staging aims at assessing treatment response and choosing methods for further treatment such as surgical resection or extended CRT. MRI with diffusion restriction is a non-invasive and useful tool for assessing the treatment response of locally advanced lower rectal cancer. It will reduce the burden of extensive abdominoperineal resection (APR) surgery in patients. Objective The purpose of this study was to determine the role of diffusion-weighted imaging (DWI) in the evaluation of post-treatment tumor response in rectal carcinoma. Materials and methods The study was approved by our institutional review board, which waived the requirement for informed consent. The clinical data of all the patients treated for rectal carcinoma at the Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore between February 1, 2014, and February 28, 2019, were retrospectively evaluated. The inclusion criteria were as follows: (1) patients with histopathologically proven rectal adenocarcinoma, (2) those who underwent APR before February 2019 at our hospital, and (3) those who underwent MRI including DWI/apparent diffusion coefficient (ADC) imaging before and after CRT. Those patients who had upfront surgery without neoadjuvant CRT and those who did not have MRI imaging with DWI/ADC were excluded from the study. Results A total of 200 patients who fulfilled the inclusion criteria were included in this study. Among those, 141 were males and 59 were females. On histology, 110 had moderately differentiated adenocarcinoma, 25 had well-differentiated adenocarcinoma, and 65 had poorly differentiated adenocarcinomas. Overall diagnostic accuracy of DWI MRI sequence was calculated to be 91%, while the sensitivity was 98.09%, specificity was 65.12%, positive predictive value was 91.12%, and negative predictive value was 90.32%. Conclusion DWI was proven to be very useful in the post-treatment evaluation of tumor response with very high diagnostic accuracy.
ABSTRACT
OBJECTIVES: Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma, which accounts for 10-15% of pulmonary cancers and exhibits early metastatic spread. This study aimed to determine the added value of 18F-FDG PET/CT imaging in tumor, node, and metastasis (TNM) staging of SCLC, compared to the conventional computed tomography (CT) scan and its potential role as a prognosticator. METHODS: This retrospective review was conducted on 23 patients, who were histopathologically diagnosed to have SCLC and referred for undergoing 18F-FDG PET/CT scanning during October 2009-December 2015. The rate of agreement between the CT and 18F-FDG PET/CT findings for TNM staging was calculated using the Cohen's kappa (κ). The median follow-up time was eight months, ranging 27-3 months). The overall and disease-free survival rates were calculated based on the extent of disease. RESULTS: 19 cases were male and four female with the mean age of 58±9 years. The 18F-FDG PET/CT identified limited and extensive diseases in 2 (8.7%) and 21 (91.3%) patients, respectively. In addition, the results of the Cohen's kappa demonstrated a strong (κ=0.82), fair (κ=0.24), and poor (κ=0.12) agreement between the PET/CT and CT findings for determining tumor, node, and metastasis stages, respectively. The 18F-FDG PET/CT scans upstaged disease in 47% of the cases with visceral and osseous metastasis. The disease-free survival rates for the limited and extensive diseases were 100% and 23% within the 12-month follow-up. In addition, 8 (35%) patients expired during the follow-up period. CONCLUSION: Improved nodal and metastatic disease identification highlights the role of 18F-FDG PET/CT scanning in initial staging of SCLC with prognostic implications.
