Page 44 - ARNM-1-2

Advances in Radiotherapy
& Nuclear Medicine SUVmax relating to patient and tumor factors

comprehensive metastatic workup. 18 F-fluoro-2- patient. This cross-sectional study was carried out in the
deoxyglucose-positron emission tomography (FDG-PET), nuclear medicine and oncology departments of a tertiary
used in conjunction with computerized tomography (CT), cancer care center in Northern India. It included all
offers precise anatomical localization and functional newly diagnosed, treatment-naïve cancer patients who
information about metabolic activity. As a result, it underwent PET/CT at the mentioned departments from
becomes a useful imaging tool in both the diagnosis and January 2019 to December 2019, encompassing patients
staging of malignant tumors [1-3] . with various cancer sites.
FDG-PET/CT is widely used in evaluating malignant 2.1. Study population
[4]
tumors . The increased uptake of 18 F-fluoro-2-
deoxyglucose ( F-FDG), an analog of glucose, serves as The study population consisted of patients diagnosed with
18
a marker of increased glycolytic activity within tumor cancers in four broad organ systems, namely, head and
tissues due to their heightened metabolism compared to neck, gastrointestinal (GI), thoracic, and gynecological
surrounding normal tissues. The advent of PET-CT has cancers. Within these systems, various sub-sites were
significantly changed cancer staging, resulting in many cases explored: (i) head–and-neck system, encompassing
being upstaged or downstaged compared to conventional nasopharynx, oropharynx, hypopharynx, larynx, oral
anatomical imaging. Consequently, this change has a cavity, and CUPS neck (carcinoma of unknown primary
substantial impact on the management of individual with secondaries in the neck) cancers; (ii) GI system,
patients. Integrated PET/CT has rapidly and widely gained covering esophageal, gastro-esophageal, rectal, and anal
clinical acceptance since its acceptance, becoming an malignancies; (iii) thoracic system, including lung cancers;
indispensable imaging tool in the management of most and (iv) gynecological system, involving cervical cancers.
solid tumors over the past decade. The exclusion criteria ensured that patients with prior
oncological surgery or prior neoadjuvant chemotherapy or
PET/CT not only visualizes but also quantifies FDG radiotherapy were excluded from our study.
uptake to differentiate metabolically highly active tissues
from less active tumor tissues. Thus, the level of cell 2.2. Imaging technique
proliferation activity in different tissues can be inferred. All patients observed a minimum fasting period of at
The maximum standardized uptake value (SUV ) is a least 6 h before undergoing PET/CT. To reduce the
max
semi-quantitative parameter commonly used in reporting muscular uptake of FDG, patients were given 5 mg of
different levels of metabolic activity in PET/CT scans [5-7] .
diazepam (a muscle relaxant) about 30 min before the
To the best of our knowledge and based on an administration of the radiolabeled drugs. The injected
extensive online literature search, demographic and amount of FDG ranged from 185 MBq to 740 MBq, based
clinicopathological factors influencing the change of on the patient’s weight (0.15 mCi/kg). Immediately before
SUV in PET have not yet been comprehensively scanning, patients were instructed to void their bladder.
max
researched or documented. However, a study on squamous In accordance with the ALARA (as low as reasonably
cell carcinomas of the tongue (TSCC) established some achievable) principle of radiation protection, the facility
relationship between SUV and clinicopathological where the patients rested had limited public access. The
max
characteristics . In addition, there are systematic average PET/CT acquisition time was between 1.5 and
[8]
reports on the relationship between SUV and 2 min. Images were acquired in 3D mode, covering from
max
clinicopathological characteristics in lung, esophageal, the base of the skull to the mid-femur level, following the
ovarian, and endometrial cancers [9-12] . The present study staging and metastatic work-up protocol. This procedure
aimed to investigate the correlation of clinicopathological was carried out 45 – 50 min after the injection of the radio-
parameters with SUV in FDG PET/CT of patients labeled drugs, using a hybrid WB-FDG PET/CT Scanner
max
of various cancer sites. The established relationship (Discovery 690, General Electric Company, USA), which
could yield additional information, such as the inherent combines a 64-slice helical CT with a full-ring dedicated
aggressiveness and natural course of various tumors PET. The imaging process commenced with a topogram
based on their SUV , as well as prognostic information, (130 kV and 30 mA), followed by a spiral CT scan (130 kV
max
including the survival outcomes of the patients. and 80 – 120 mA), and concluded with an automated PET.
The CT images were obtained without the administration
2. Methods of intravenous contrast. A CT-based attenuation correction
Our study was approved by the Institutional Review factor was generated for the PET data, and the images
Board of Command Hospital (CC), Lucknow, and were reconstructed using digital geometrical processing
written informed consent was obtained from every and tomographic reconstruction employing a standard

Volume 1 Issue 2 (2024) 2 https://doi.org/10.36922/arnm.2032