Combined modalities to obtain better accuracy

February 5, 2019 0 By S Harachand

The rapid development of positron emission tomography (PET) and MR technology in the last few decades has led to multimodality imaging devices.

Combining PET and CT scanning, radiologists can better detect changes in lesions over time. This can also provide information on the nature of growth. The clinician will be able to know whether the growth is stable, quick, and if the patient is not responding to treatment.

A new generation of hybrid scanners with integrated PET and single-photon emission computed tomography (SPECT) with CT is a considered option for patients with recurrent ovarian cancer. PET/CT detects more lesions than PET or CT alone. PET/CT permits the exact anatomical localisation of pathologic tracer uptake. This will help the oncologist to direct treatment to the precise site of tumour recurrence. Hence, PET/CT should be considered for follow-up of patients with ovarian cancer.

Adding CT perfusion (CTP) imaging is a safe and powerful tool to improve the accuracy and the positive predictive value of coronary computed tomography angiography (CTA) alone, shows current evidence. The combination of CTP with CTA not only provides anatomic information concerning luminal stenosis, plaque morphology, and total plaque burden but also provides data on myocardial tissue hemodynamics.

Different acquisition protocols for CTP imaging can assess myocardial perfusion in a qualitative, semiquantitative, or quantitative manner. It holds immense potential to evaluate almost every aspect of the broad spectra of ischemic heart disease with the possibility of guiding treatment decisions for a patient on an individual basis, researchers say.

Recently, cardiovascular PET-CT has emerged as an imaging technology with the potential to simultaneously describe both anatomical structures and physiological processes in vivo. PET-CT has tremendous clinical application. Studies are underway to explore these possibilities.

“Fusion imaging is now catching up very fast among various clinical disciplines,” says Dr Shanmugham, a consultant radiologist from Tuticorin, Tamil Nadu. “Almost all the imaging modalities have their own limitations. Combining different technologies can provide better characterisation and clarity in many clinical situations where an assessment becomes challenging.”

In some cases, for example in a bone tumour, CT/MRI can be preferred. “It harnesses the strength of both CT and MRI. While one modality helps determine the status of bone marrow, the other gives a better view of the bone tissue. Combining both, the clinician will get a highly detailed picture of the condition,” informs Dr A Anbarasu, a consultant radiologist and imaging specialist from Coimbatore, Tamil Nadu and the author of Oxford Handbook of Head and Neck Imaging – an introduction to the theory and practice of head and neck radiology.

Ultrasound has its limitations in poorly echogenic patients or organs. Such difficult-to-visualize lesion can be rendered visible by Smart Fusion, a technique that combines imaging modalities. Smart Navigation, a needle tracking technology, allows for oblique needle paths and real-time monitoring at the patient’s bedside without exposing him or her to ionizing radiation. Both Smart Fusion and Smart Navigation are more accessible and less expensive than a procedure performed under CT or MRI guidance. This modality is especially useful in interventional radiology settings.

PET/MR imaging can be beneficial to improve early and differential diagnosis of Alzheimer’s disease, studies show. Through combining the metabolic and molecular information from PET, and the structural and functional information from MR imaging, PET/MR imaging is considered to have the potential to broaden diagnostic power. With new emerging PET radiotracers and MR imaging techniques, it could become a conventional first-line one-stop-shop clinical imaging tool to improve the current understanding of AD