Use of Spect Ct Scan in Diagnosing Radiation Induced Pulmonary Artery Stenosis

The use of computed tomography of chest(CT Chest) for evaluation of acute dyspnea has increased 5 folds in the last decade, and is the preferred investigation of choice for diagnosing pulmonary embolism(PE), although studies have shown equal efficacy of CT scan and ventilation and perfusion(V/Q) scan. The modern multidectector CT Chest can reliably identify smaller clots even in sub segmental pulmonary arteries and also precisely quantify the right ventricular functions aiding in thrombolytic therapy for PE. However, renal failure limits the use of this test due to risk of contrast induced nephropathy. Planer V/Q scans lack spatial resolution and often reported as indeterminate limiting their widespread application. The addition of single photon emission computer tomography (SPECT) to V/Q scan can overcome this problem and gives excellent anatomical details of lungs leading to growing popularity among physicians. We present a case of radiation induced pulmonary artery stenosis which was accurately identified by SPECT CT scan, missed by CT pulmonary angiogram(CTPA).