Dosimetry Study in Head and Neck of Anthropomorphic Phantoms in Computed Tomography Scans

Background The aim of this study is to evaluate the diagnostic performance of contrast-enhanced computed tomography (CECT) and 2-[Fluorine-18] fluoro-2-deoxy-d-glucose positron emission tomography combined to computed tomography (18 F-FDG PET/CT) in assessment of lymphoma. Methods Hundred patients, pathologically proven as lymphoma, were evaluated by CECT and 18F-FDG PET/CT for initial assessment and staging of the disease. The number of lesions and the disease stage detected by each modality was calculated and further analyzed to be compared. Results 18F-FDG PET/CT diagnosed a total number of 545 lymphoma involved regions with sensitivity 96.6%, specificity 98.8%, and accuracy 99% that was higher than CECT which diagnosed a total number of 439 lymphomatous regions with sensitivity 87.5%, specificity 85.7%, and accuracy 88%. Discordant staging by both modalities was found in 23% of the patients. Lymphoma was upstaged by PET/CT in 17% of the patients; with major changes in 12% of them and downstaged in 6% of the patients. Conclusion 18F-FDG PET/CT scan has a better diagnostic performance, represented by sensitivity, specificity, and accuracy, than CECT scan in the initial assessment of lymphoma regarding its nodal and extra-nodal lesions that could lead to alteration of disease staging which in turn markedly affecting the decision of treatment regimens.

Section: Scanning Technique and Imaging Parameterssupporting

confidence: 90%

“…For this purpose, 100 patients diagnosed as lymphoma, which proved and classified by histopathology, were initially assessed and staged by CECT and 18F-FDG PET/ CT(Figs. 8,9,10,11,12,13,14,15,16,and 17).…”

mentioning

confidence: 99%

PET/CT and contrast-enhanced CT: making a difference in assessment and staging of patients with lymphoma

Zytoon

Mohamed

Mostafa

et al. 2020

“…If PET/CT will be adding to routine follow-up program of CMM patients, it would be strongly helpful if the radiation could be restricted to an absolute minimum. New dosimetry studies performed with phantoms of identical characteristics, using thermoluminescent dosimeters (TLDs) placed in regions close to the region where this study conducted, and identified lower dose values [24] This study had many limitations: the nature of study as a retrospective, small number size of studied patients in each group, and high dose of radiation; we should use low-dose radiation CT if follow-up done as a protocol, high cost of PET-CT epically in developing countries.…”

Section: Discussionmentioning

confidence: 98%

PET/CT in restaging, prognosis, and recurrence in patients with malignant melanoma

El-Shourbagy

Mashaly

Khodair

et al. 2020

Background: Cutaneous malignant melanoma (CMM) is a highly aggressive tumor with high tendency of return despite complete surgical removal. It has a high risk of dissemination to regional lymph nodes and visceral organs. The prognosis is highly dependent on lymph node involvement and distant metastases. Positron Emission Tomography with Computed Tomography (PET/CT) is a valuable non-invasive tool for the diagnosis and staging of patients with MM. The purpose of the present study was to evaluate the role of integrated (PET/CT) in staging, restaging, prognosis, and prediction of recurrence in patients with malignant melanoma. Results: Fifty malignant melanoma patients with age ranged from 28 to74 years (mean age 55.94 + 13.40 years) were 28 males (mean age 56.71 + 12.82) and 22 females (mean age 54.95 + 14.34). All our patients were histopathologically proven to have malignant melanoma. Twenty-one patients came for initial staging by 18F-FDG PET/CT. Their findings were compared with the reference standards and showed the sensitivity of 93.33%, specificity of 60%, and accuracy of 85.71% for primary staging. 18F-FDG PET/CT scan in 11 clinical suspicion patients of relapse after treatment showed the sensitivity of 100%, specificity of 66.66%, positive predictive value of 88.88%; negative predictive value of 100%; and accuracy of 90.90%. FDG-PET/CT of whole body scan in 18 cases of stage IV melanoma showed sensitivity of 100%, specificity of 66.66%, and overall accuracy of 94.44% for detection of distant metastases. SUVmean and SUVmax in all studied groups were significantly higher in true positive more than true negative or false-positive patients diagnosed by PET/CT with high sensitivity (82.88-100%). Conclusion: PET/CT imaging enhanced diagnostic performance in detection of the primary malignancy, in followup of high-risk patients and patients with suspected or known local or distant recurrence, and in restaging of patients with known distant metastatic disease to assess tumor response.

“…Radiation exposure could be considered a downside of the discussed modality; however, Osipov et al showed that diagnostic exposure due to repeated PET-CT examinations in a group of oncological patients was not associated with changes in mortality [47]. Reduced kilovolts (kVs) with automatic exposure control were a suggested attempt to optimize the radiation exposure in head and neck scans [48]. We should recognize limitations in the current study as there was lack of a histological proof as a true reference standard for some of the detected lesions.…”

Section: Discussionmentioning

confidence: 99%

Brain metastases assessment by FDG-PET/CT: can it eliminate the necessity for dedicated brain imaging?

Zidan

Hassan

El-Noueam

et al. 2020

Background Brain metastases (BM) are the most common intracranial tumors in adults outnumbering all other intracranial neoplasms. Positron emission tomography combined with computed tomography (PET/CT) is a widely used imaging modality in oncology with a unique combination of cross-sectional anatomic information provided by CT and the metabolic information provided by PET using the [18F]-2-fluoro-2-deoxy-d-glucose (FDG) as a tracer. The aim of the study is to assess the role and diagnostic performance of brain-included whole-body PET/CT in detection and evaluation of BM and when further imaging is considered necessary. The study was conducted over a period of 12 months on 420 patients suffering from extra-cranial malignancies utilizing brain-included whole-body PET/CT. Results Thirty patients with 71 brain lesions were detected, 18 patients (60%) had BM of unknown origin while 12 patients (40%) presented with known primary tumors. After brain-included whole-body FDG-PET/CT examination, the unknown primaries turned out to be bronchogenic carcinoma in 10 patients (33.3%), renal cell carcinoma in 2 patients (6.7%), and lymphoma in 2 patients (6.7%), yet the primary tumors remained unknown in 4 patients (13.3%). In 61 lesions (85.9%), the max SUV ranged from 0.2- < 10, while in 10 lesions (14.1%) the max SUV ranged from 10 to 20. Hypometabolic lesions were reported in 41 (57.7%) lesions, hypermetabolic in 3 lesions (4.2%), whereas 27 lesions (38.0%) showed similar FDG uptake to the corresponding contralateral brain matter. PET/CT overall sensitivity, specificity, positive and negative predictive, and accuracy values were 78.1, 92.6, 83.3, 90, and 88% respectively. Conclusion Brain-included whole-body FDG-PET/CT provides valuable complementary information in the evaluation of patients with suspected BM. However, the diagnostic performance of brain PET-CT carries the possibility of false-negative results with consequent false sense of security. The clinicians should learn about the possible pitfalls of PET/CT interpretation to direct patients with persistent neurological symptoms or high suspicion for BM for further dedicated CNS imaging.