Appropriate indications for positron emission tomography/computed tomography: College of Nuclear Physicians of the Colleges of Medicine of South Africa

Abstract

A patient-tailored treatment approach demands precise determin ation of initial disease extent combined with early, accurate assessment of response to treatment. Positron emission tomography/computed tomography (PET/CT) is currently the most widely used molecular imaging technology and is central to the advancement of patient care and biological research. [1,2] PET/CT whole-body imaging PET is a non-invasive tool that provides tomographic images and quantitative parameters of perfusion, cell viability, and proliferation and/or metabolic activity of tissues. These images result from the use of various biological compounds (such as sugars, amino acids, metabolic precursors and hormones) labelled with positronemitting radionuclides (PET radiopharmaceuticals).[1] Fusion of the functional information with the morphological detail provided by CT as PET/CT can provide clinicians with a sensitive and accurate one-step whole-body diagnostic and prognostic tool, which directs and changes patient management. [1,3] Several studies have demonstrated the superiority of combined PET/CT over either modality alone, and for many indications this is generally accepted as the gold standard for imaging in oncol ogy. [4] The value of PET/CT imaging has been best demonstrated in the setting of oncology with the use of fluorine-18-fluorodeoxyglucose ( 18 F-FDG). FDG is an analogue of glucose and is taken up by cells via the first stages of the normal glucose pathway and trapped inside cells with high glucose transporter expression and/or glycolytic activity. Tumour uptake therefore correlates with tumour growth and viability, providing metabolic quantification and frequently useful information for tumour characterisation, patient prognosis and monitoring of therapeutic response.[1] Impact on the management of oncology patientsCurrent data suggest that in as many as one-third to one-half of cancer cases, physicians without access to PET are at an increased risk of selecting the wrong management/treatment strategy for their patients. Three large-scale national studies published by the National Oncologic PET Registry in the USA have shown that PET imaging changes the intended patient management strategy in 36.5%, 38% and 49% of cases, respectively. [5][6][7] Results were consistent across all cancer types.[6] A recent study by Worsley et al. [8] found that the information derived from PET Individualised patient treatment approaches demand precise determination of initial disease extent combined with early, accurate assessment of response to treatment, which is made possible by positron emission tomography/computed tomography (PET/CT). PET is a non-invasive tool that provides tomographic images and quantitative parameters of perfusion, cell viability, proliferation and/or metabolic activity of tissues. Fusion of the functional information with the morphological detail provided by CT as PET/CT can provide clinicians with a sensitive and accurate one-step whole-body diagnostic and prognostic tool, which directs and changes patient management...

The utility of bone marrow sampling in the diagnosis and staging of lymphoma in South Africa

“…Although the number of CT scanners in SA is adequate for emergencies, there may be prolonged waiting times for their use in other situations. The PET scanners available for public sector use (considered inadequate in number by WHO standards) are situated in major urban academic centres, which also results in delays and restricted use. Additionally, special care is required in the interpretation of PET‐CT in HIV‐related lymphoma, where false‐positive findings occur .…”

Inter-observer variability influences the Lugano classification when restaging lymphoma

“…HIV-associated lymphadenopathy in patients with active viral replication may be metabolically active with PET-CT, as will lymphoma. 5 Assigning lung infiltrates, consolidation or nodules as either due to infection or lymphoma is particularly problematic in the local patient population, given the high burden of HIV and TB.…”

“…4 Internationally, combined positron emission tomography and computed tomography (PET-CT) is considered to be the principal imaging method for staging and restaging of lymphoma, although stand-alone CT is regarded as an acceptable alternative when PET-CT is unavailable. 5,6…”

Disease severity and status in Stevens–Johnson syndrome and toxic epidermal necrolysis: Key knowledge gaps and research needs

“…Fluorodeoxyglucose (FDG) is a radiolabeled analog of glucose and is taken up by cells via the first stages of the normal glucose pathway and trapped inside cells with high glycolytic activity. FDG uptake is quantifiable and correlates with metabolic activity, providing useful information on disease severity, disease progression, and therapeutic response ( 103 ). FDG-PET/CT has been used successfully to identify, localize, and quantify inflammation in vivo in an array of inflammatory conditions affecting the eye, RS, GIT, GUT, and the cardiovascular system.…”