V/Q Scanning Using SPECT and SPECT/CT

Abstract

Learning Objectives: On successful completion of this activity, participants should be able to describe (1) advantages and shortcomings of planar versus SPECT V/Q scanning, (2) advantages and disadvantages of CT pulmonary angiography versus V/Q SPECT in the investigation of pulmonary embolism, and (3) an overview of image acquisition, processing, display, and reporting of V/Q SPECT studies.Financial Disclosure: The authors of this article have indicated no relevant relationships that could be perceived as a real or apparent conflict of interest. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, participants can access this activity through the SNMMI Web site (http:// www.snmmi.org/ce_online) through September 2016.Planar ventilation-perfusion ( V/Q) scanning is often used to investigate pulmonary embolism; however, it has well-recognized limitations. SPECT overcomes many of these through its ability to generate 3-dimensional imaging data. V/Q SPECT has higher sensitivity, specificity, and accuracy than planar imaging and a lower indeterminate rate. SPECT allows for new ways to display and analyze data, such as parametric V/Q ratio images. Compared with CT pulmonary angiography, SPECT has higher sensitivity, a lower radiation dose, fewer technically suboptimal studies, and no contrast-related complications. Any nuclear medicine department equipped with a modern hybrid scanner can now perform combined V/Q SPECT with CT (using low-dose protocols) to further enhance diagnostic accuracy. V/Q SPECT (with or without CT) has application in other pulmonary conditions and in research. Si nce its first description by Wagner et al. in 1964 (1), the planar lung scan has been one of the most commonly performed studies in nuclear medicine. It is, however, a test with significant limitations, which have had an adverse impact on its reputation (2,3). Because planar imaging is a 2-dimensional technique, it has inherent limitations, especially related to overlap of anatomic segments. Assigning defects to specific lung segments is often difficult, and the variability in segment size and shape between patients makes accurate determination of the extent of embolic involvement in individual segments a challenge (2). Embolic defects may not be detected if there is shine-through from underlying lung segments with normal perfusion, thus resulting in an underestimation of the extent of perfusion loss (4). Furthermore, the medial basal segment of the right lower lobe is often not visualized on planar scans (2,5). Added to these factors is the widespread use of probabilistic reporting criteria, and a relatively high indeterminate rate, both of which have caused significant dissatisfaction among referring physicians (6,7). ...

Pulmonary embolism: clinical guidelines of European Society of Cardiology (2014).The Task Force of the European Society of Cardiology for diagnosis and management of pulmonary embolism

“…Цель вентиляционного сканирования -повышение специфичности исследо вания: при острой ТЭЛА в гипоперфузируемых сег ментах легочной ткани вентиляция не изменена (дисбаланс) [145,146]. В соответствии с данными Международной комиссии по радиационной безопас ности (ICRP) радиационное воздействие при ска нировании легких взрослого человека среднего тело сложения с 100 МБк макроаггрегированных частиц альбумина, меченых Tc 99m, в среднем составляет 1,1 мЗв и, следовательно, гораздо ниже, чем при КТ ангиографии (2-6 мЗв) [147,148].…”

Diagnostic Imaging in Acute Pulmonary Embolism

“…BTPA, SPECT V/P, ve planar V/P sintigrafisi arasında karşılaştırmalar sınırıdır. Ancak bu konu ile ilgili ilk veriler SPECT V/P'nin BTPA ile benzer doğruluğa sahip olduğunu göstermektedir (21).…”

Pulmoner emboli tanısında D-dimer düzeyleri ile ventilasyon/perfüzyon sintigrafisindeki bulgular arasındaki ilişki

“…Örnek olarak sağ akciğer alt lob medial bazal segment planar çekimlerde genellikle görüntülenemez. Bu sorun V/P sintigrafisinin sensitivitesi ve spesifitesi yüksek olan SPECT/BT ile elde edilmesi sayesinde aşılabilmektedir [10]. Ventilasyon/perfüzyon sintigrafisinin yorumlanmasında PİOPED kriterleri kullanılmaktadır.…”