Dual-Modality Imaging: More Than the Sum of its Components

Abstract

The field of diagnostic radiology encompasses a wealth of imaging techniques that now are essential for evaluating andmanaging patients who needmedical care. Traditional imaging methods such as plain film radiography and more recent techniques such as x-ray computed tomography (CT) and magnetic resonance imaging (MRI) can be used to evaluate a patient’s anatomy with submillimeter spatial resolution to discern structural abnormalities and to evaluate the location and extent of disease. Thesemethods also offer relatively fast scan times, precise statistical characteristics, and good tissue contrast especially when contrast media are administered to the patient. In addition, x-ray fluoroscopy and angiography can be used to evaluate the patency of blood vessels, the mechanical performance of the cardiovascular system, and structural abnormalities in the gastrointestinal or genitourinary systems. Similarly,CTandMRIcanbeperformedwithcardiacgatingtotheheartatdifferent phases of the cardiac cycle. Computed tomography recently has experienced a significant increase in utilization with the advent of multislice helical scanning techniques that cover a large region of the patient’s anatomy within a single breath-hold, with scan speeds that can capture both the arterial and venous phases of the contrast bolus. These increased scan speeds also enhance patient comfort, and contribute to patient throughput and cost effectiveness. X-ray projection imaging, computed tomography, and magnetic resonance imaging differentiate disease from normal tissue by revealing structural differences or differences in regional perfusion of the administered contrast media. The interpretation of the images can be complicated when normal perfusion patterns are disrupted by prior surgery or radiation therapy, which can lead to tissue damage or necrosis where contrast patterns can mimic