Interpretation and reporting of positron emission tomography-computed tomographic scans

Body oncology positron emission tomography-computed tomographic (PET-CT) exams are particularly complex and time-consuming studies to interpret and report. An integrated approach is required to provide the referring physician with the full clinical value of this combined modality. Special attention to the Positron Emission Tomography-Computed Tomographic Report Findings section and Impression section is necessary to insure all the information relevant to the patient's care are clearly communicated to the referring physicians.     

Positron emission tomography in oncology

Summary. The particular advantages of positron emission tomography (PET) technique are that it has higher sensitivity, higher resolution, and a higher quality of image than that found in conventional nuclear medicine. The possibility of quantification and the wide range of useful tracers have raised expectations of this new method. To date, most of the human PET cancer studies have been performed with [¹⁸F]fluorodeoxyglucose (FDG) or [¹¹CJmethionine. These are good imaging agents for tumours. However, more specific radiopharmaceuticals are required if other features of tumour metabolism are to be observed, f¹¹Thymidine may prove to be a good tracer for quantitative measurements of tumour proliferation and [¹⁸F]misonidazole has been suggested for imaging of hypoxia.     

Positron emission tomography in oncology

Positron emission tomography (PET) scans use positrons, positively charged particles, to detect metabolic and chemical changes in the body. Although the clinical applications of this technology still are evolving, PET scans are being used to detect cancer and evaluate neurologic disorders, heart muscle function, and response to treatment. In oncology, PET scans may be used to determine biopsy location, stage disease, diagnose cancer recurrence, and discern malignant from benign conditions. PET scans also have led to the incidental diagnosis of cancer. This article reviews patient preparation and PET scan procedures and includes a patient information sheet on PET scanning. Oncology nurses need to be well informed about new technologies used in cancer care, such as PET scans, to better educate and prepare patients to undergo these tests.     

Positron emission tomography and epilepsy.

PURPOSE: This review examines the current role of positron emission tomography (PET) in the investigation and management of patients with epilepsy. PROCEDURES: A literature review utilizing MEDLINE(R) and other sources was undertaken. For the comparison of the accuracy of PET with magnetic resonance imaging (MRI) for seizure focus localization, only publications since 1994 were examined. Individual patient data was tabulated to provide figures for seizure focus localization rates for different types of focal epilepsy and the prognostic value of PET findings for epilepsy surgery outcome. RESULTS: The majority of PET studies used 2-deoxy-2-[18F]fluoro-D-glucose (FDG). The epileptogenic sites typically show reduced FDG uptake (hypometabolism). In patients with intractable temporal lobe epilepsy (TLE), unilateral temporal lobe hypometabolism (UTH) corresponding to the seizure focus was seen in 86% of patients. In the same population, MRI demonstrated relevant abnormalities in 76%. UTH contralateral to the seizure focus was rarely seen (3%). Following temporal lobectomy, 86% of patients with ipsilateral UTH had a good outcome. When MRI was normal, UTH predicted a good outcome in 82%. Fifty percent with bitemporal hypometabolism had independent bilateral foci, and in those who proceeded to surgery only 50% had a good result. In extratemporal epilepsy, hypometabolism relevant to the focus was seen in 67% but, as in TLE, it was often more extensive than pathological abnormality. Recently evidence of a role for 11C-Flumazenil has emerged with reduced binding in the primary epileptogenic site. 11C-Flumazenil abnormalities appear more restricted to abnormal cortex and may be a better guide to the extent of resection required for surgical success. CONCLUSIONS: FDG-PET has a key role in the evaluation of patients with intractable partial epilepsy, particularly when surgery is a treatment option. Development and application of more specific biochemical probes may further improve the clinical value of PET for the understanding and treatment of epilepsy.     

Positron emission tomography-computed tomography patient management and workflow

This article reviews the major considerations involved in optimizing positron emission tomography-computed tomographic (PET-CT) workflows including patient management and specific acquisition, processing, and archiving procedures. Due to the dual modality nature of PET-CT and the needs of the patients typically undergoing these examinations, there is a high level of patient contact and interaction with the technologists and ancillary personnel. Each PET-CT scan itself generates a considerable volume of raw image data which must be reconstructed, and the reconstructed images distributed and archived without impeding overall workflow. PET-CT facility design and layout, the procedures for sequencing patients through each phase of the exam, and adequate staffing are important considerations for an efficient and high-quality service.     

Positron emission tomography and central neurotransmitter systems in movement disorders

Summary— This article discusses the anatomical and neurochemical structure of the basal ganglia and reviews the Positron Emission Tomographic (PET) ligands available for investigating these pathways. We discuss how clinical PET studies have improved our understanding of the neurochemical changes underlying principal movement disorders.     

Discrepancies in interpretation of ED body computed tomographic scans by radiology residents

OBJECTIVE: In academic institutions, radiology residents are often relied on for providing preliminary reports of imaging studies done in the ED. We examined the prevalence of discrepant interpretations of body computed tomographic (CT) scans in our institution. METHODS: We conducted a retrospective study on a consecutive series of body CT scans at an urban ED. We compared the preliminary interpretation by radiology residents with the final interpretation by radiology attending physicians. An interpretation was characterized as having no discrepancy, minor discrepancy, or major discrepancy. A major discrepancy was defined as a discrepancy that resulted in a change in diagnosis, treatment, or disposition. RESULTS: Two hundred three body CT scans were identified during the study period. Of these CT scans, 20 had major discrepancies (10%), 40 had minor discrepancies (20%), and 143 had no discrepancy (70%). Major discrepancies included missed appendicitis, normal appendix, missed bowel obstruction, and missed colon cancer. Computed tomographic scans with abnormal findings were more likely to contain major discrepancies (relative risk = 6.0; 95% confidence interval = 1.8-2.0). CONCLUSION: Discrepancies between radiology residents and radiology attending physicians were common at our institution. Emergency department physicians should exercise caution when relying on residents' interpretation of body CT scans.     

Positron emission tomography/computed tomography hypermetabolism of Kikuchi–Fujimoto disease mimicking malignant lymphoma: a case report and literature review

Kikuchi–Fujimoto disease (KFD), also known as histiocytic necrotizing lymphadenitis, is a benign, self-limiting inflammatory disorder of unknown etiology and pathogenesis. This report presents a rare case involving a man with ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) hypermetabolism caused by KFD mimicking malignant lymphoma. The PET/CT maximum intensity projection showed multiple hypermetabolic lymphadenopathies and homogeneous FDG uptake in the bone marrow and spleen. Malignant lymphoma was initially suspected. The patient then underwent excision biopsy of one enlarged right cervical lymph node that was selected because it showed the highest FDG uptake in PET/CT, and examination of this biopsy specimen confirmed the diagnosis of KFD. PET/CT is useful for assessing the general condition of patients and can help to select lymph nodes for excision biopsy based on the highest FDG uptake. However, KFD can predispose to localized FDG uptake and limit the specificity of PET/CT by mimicking malignancy. Thus, positive results of PET/CT should be interpreted with caution.     

Positron emission tomography in the diagnosis and management of giant cell arteritis

We describe a 58-year-old woman who presented with new onset of temporal headaches and a nondiagnostic temporal artery biopsy in whom positron emission tomography led to the diagnosis of giant cell arteritis. After treatment with corticosteroids the patient's symptoms resolved. A repeat (18)FDG PET-CT scan illustrated virtually complete resolution of the abnormal (18)FDG uptake in the arterial wall.