A pulmonary embolism (PE) that obstructs pulmonary arterial blood flow is a medical emergency. Its early detection and appropriate management can be lifesaving. CT pulmonary angiography (CTPA) is currently in use as a standard tool for diagnosis of PE. This study was performed to determine the prognostic accuracy of contrast reflux into the inferior vena cava (IVC) and hepatic veins on CTPA in patients suffering from acute PE. Materials and Methods The study was composed of 285 patients between 15 to 85 years of age that had filling defects in pulmonary arteries on CTPA that were consistent with those of a pulmonary embolism. The extent of contrast reflux into the IVC and hepatic veins was determined on the basis of a Groves scale. The patients were followed for a period of 30 days. Results Of 285 total patients, 200 (70.17%) survived the post PE period of 30 days and were labeled as survivors. The other 85 (29.83%) patients did not survive the 30-day duration and were called non-survivors. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of IVC contrast reflux grading were 65.8%, 90%, 73.68%, 86.12 % and 82.8 % respectively. Conclusion We conclude that IVC contrast reflux grading assessed on helical CT is a beneficial tool for predicting prognosis in cases of acute PE.

OBJECTIVE - The purpose of this study was to assess the radiation dose levels from common computed tomography (CT) examinations performed in Radiology Department of Pakistan Institute of Medical Sciences (PIMS), and evaluate these according to diagnostic reference levels (DRLs) proposed by European Commission (EC) guidelines, and thus contributing towards the establishment of local and national DRLs. To the best of our knowledge, this is the first study of its kind to explore radiation doses from CT examinations in Pakistan. STUDY DESIGN - This was a quantitative study conducted at PIMS, Islamabad, spanning a duration of eight weeks. Scan parameters and dose profile data of 1506 adults undergoing examinations of head, neck, chest and abdomen-pelvis regions, comprising of single- and multi-phase, contrast-enhanced and unenhanced studies. Dose indicators utilized by EC guidelines for DRLs include volume CT dose index (CTDIvol) and Dose Length Product (DLP) for single slice and complete examination radiation doses, respectively. METHOD - Values of CTDIvol, DLP and scan lengths were extracted from the CT operators console. Other control variables included gender, contrast enhancement and phasicity of study. IBM SPSS package was used to obtain descriptive statistics such as mean and quartiles. RESULTS - DRLs calculated as 75th percentile of CTDIvol, DLP for various anatomical regions are by and far comparable to European DRLs. CONCLUSION – This study describes institutional diagnostic reference levels for common CT exams in Islamabad and provides benchmark values for future reference. Our DRL values are mostly comparable to European and international DRLs. Similar, albeit large scale, surveys are recommended for establishment of local and national DRLs, eventually contributing towards development of regional DRLs. KEYWORDS: CTDIvol, DLP, Diagnostic Reference Levels, Computed Tomography, Radiation Monitoring, Scan length