Scientific Literature: hybrid imaging

The number of peer-reviewed papers covering the field of hybrid imaging is burgeoning, to such an extent that it is frequently difficult for healthcare professionals to keep up with the literature. As a special service to our readers, International Hospital presents a few key literature abstracts from the clinical and scientific literature chosen by our editorial board as being particularly worthy of attention.

Physical attributes, limitations, and future potential for PET and SPECT.

Garcia EV. J Nucl Cardiol. 2011 Dec 10.

Advances in SPECT and PET imaging hardware, software, and radiotracers are vastly improving the non-invasive evaluation of myocardial perfusion and function. In contrast to traditional dual-headed, sodium iodide crystal and photomultiplier cameras with mechanical collimators, new SPECT camera designs utilise novel collimators and solid-state detectors that convert photons directly to electrical signals. These cameras simultaneously collect data from as many as 76 small detectors narrowly focused on the heart. New noise regularisation and resolution recovery/noise reduction reconstruction software interprets emitted counts more efficiently and thus more effectively discriminates between useful signals and noise. As a result, shorter acquisition times and/or lower tracer doses produce higher quality SPECT images than were possible before. PET perfusion imaging has benefitted from the introduction of novel detectors that now allow true 3D imaging, new radiopharmaceuticals, and precise attenuation correction (AC). These developments have resulted in perfusion images with higher spatial and contrast resolution that may be acquired in shorter protocols and/or with less patient radiation exposure than traditional SPECT. Hybrid SPECT/CT and PET/CT cameras utilise transmission computed tomographic (CT) scans for AC, and offer the additional clinical advantages of evaluating coronary calcium, myocardial anatomy (including non-invasive CT angiography), myocardial function and myocardial perfusion in a single imaging procedure.

Bone scintigraphy in breast cancer: added value of hybrid SPECT-CT and its impact on patient management.

Sharma P et al. Nucl Med Commun 2011 Dec 7.

This study evaluated the incremental value of single-photon emission computed tomography-computed tomography (SPECT-CT) over planar scintigraphy and SPECT alone for equivocal bone scintigraphy lesions in patients with breast cancer and to assess its impact on patient management. A total of 102 patients with 115 equivocal lesions on planar scintigraphy underwent SPECT and SPECT-CT of selected volume. Images were evaluated in separate sessions to minimise recall bias. A scoring scale of 1-5 was used, where 1 is definitely metastatic, 2 is probably metastatic, 3 is indeterminate, 4 is probably benign, and 5 is definitely benign. With receiver operating characteristic analysis, area under the curves was constructed for each modality. Clinical/imaging follow-up and/or histopathology were taken as the reference standard. There were 52 indeterminate lesions on planar scintigraphy, 15 on SPECT, and three on SPECT-CT. Area under the curve for SPECT-CT was significantly larger compared with planar scintigraphy (P<0.001) and SPECT (P=0.033). This improvement was mostly for lytic lesions (P<0.0001). In patients (n=67) in whom the lesions under evaluation were the only lesions and hence whose management was decided, SPECT-CT was superior to SPECT (P=0.045) and planar scintigraphy (P <0.001). SPECT-CT is thus better than planar scintigraphy and SPECT alone for characterising equivocal bone scintigraphy lesions in patients with breast cancer and can have a significant impact on patient management. Combined anatomical and functional imaging using coronary CT angiography and myocardial perfusion SPECT in symptomatic adults with abnormal origin of a coronary artery.

Uebleis C et al. Int J Cardiovasc Imaging. 2011 Dec 7.

There has been a lack of standardised workup guidelines for patients with congenital abnormal origin of a coronary artery from the opposite sinus (ACAOS). This study evaluated the use of cardiac hybrid imaging using multi-detector row CT (MDCT) for coronary CT angiography (Coronary CTA) and stress-rest myocardial perfusion SPECT (MPS) for comprehensive diagnosis of symptomatic adult patients with ACAOS. Seventeen symptomatic patients (12 men; 54