PET and PET/CT imaging: what clinicians need to know

Positron emission tomography (PET), once the sole province of academic medical centers, is rapidly being adopted in daily clinical practice in community hospitals and outpatient centers. It can be especially useful in oncology, cardiology, and neurology. We provide an overview of the fundamentals of PET and PET with computed tomography (PET/CT) and discuss their current clinical utility.     

Mediastinal staging of non-small cell lung carcinoma using computed and positron-emission tomography

BACKGROUND: We evaluated the accuracy of computed tomography (CT) and positron-emission tomography (PET) in the mediastinal staging of non-small cell lung cancer. METHODS: Between May 14, 1999, and November 28, 2000, computerized tomography (CT) and positron-emission tomography (PET) were used to clinically stage 94 consecutive patients with non-small cell carcinoma of the lung (NSCCL). All patients underwent subsequent surgical staging with mediastinoscopy, anterior mediastinotomy, and/or thoracotomy with mediastinal lymphadenectomy. RESULTS: Overall accuracy was the same for both procedures. False-negative results occurred 3 times more often with CT; false-positive results occurred twice as often with PET. Sensitivity and specificity were 64% and 94%, respectively, for CT, versus 88% and 86%, respectively, for PET. Positive and negative predictive values were 80% and 88%, respectively, for CT, versus 71% and 95%, respectively, for PET. CONCLUSION: In addition to routine use of CT, PET seems to achieve high negative predictive value in the evaluation of mediastinal disease; PET seems particularly helpful in assessing absence of tumor in bulky nodes after neoadjuvant chemotherapy and/or radiotherapy.     

Staging and follow-up of gastrointestinal tumors with PET/CT

Positron emission tomography (PET) is a functional imaging modality that has been documented to be useful in patient care. Oncologic PET imaging is used for a wide variety of neoplasms, mainly for staging and follow-up, differentiation of equivocal morphologic findings, therapy stratification, and monitoring. Because PET imaging is based on the physiologically mediated distribution of the administered tracer but not on anatomic information, the addition of computed tomography (CT) to PET may improve the interpretation of PET. Combined PET and CT offers several potential advantages over PET alone that may influence the clinical routine. PET/CT was introduced into clinical use only 3 years ago and has found widespread application within only 1 to 2 years. This article summarizes preliminary data of clinical applications for PET/CT in gastrointestinal tumors.     

I-124-PET/US Fusion Imaging in Comparison to Conventional Diagnostics and Tc-99m Pertechnetate SPECT/US Fusion Imaging for the Function Assessment of Thyroid Nodules

The purpose of this study is to investigate I-124 positron emission tomography (PET)/ultrasound (US) fusion imaging for function assessment of thyroid nodules. In 70 patients, 201 lesions were examined with conventional diagnostics (CD) (thyroid US, laboratory findings and Tc-99m pertechnetate scintigraphy), Tc-99m pertechnetate single photon emission computed tomography (SPECT) and I-124 PET/computed tomography (CT). Subsequently, US fusion imaging (SPECT/US and PET/US) was performed by three experienced investigators. Patients referred for thyroid diagnostics in a clinical routine setting were included in this study if CD produced equivocal results. PET/US was superior to CD and SPECT/US in 96% and 86%, respectively, and ambiguous findings in CD were clarified by PET/US in 96% of the 70 patients. Regarding nodule-based function assessment, 10% (66%), 39% (14%) and 71% (4%) of the 201 lesions were rated with absolute certainty (equivocal or uncertain) using CD, SPECT/US and PET/US, respectively (p < 0.001). PET/US has the potential to improve the function assessment of thyroid nodules in comparison to CD.     

Novel and Simple Carbon-11-Labeled Ammonium Salts as PET Agents for Myocardial Perfusion Imaging

Background  

Positron emission tomography (PET) has clear advantages over single photon emission computed tomography (SPECT) in the field of myocardial perfusion scintigraphy (MPS); however, there are just a small number of efficient PET tracers available today for MPS. We sought to develop and perform a preliminary biological evaluation of novel carbon-11-labeled ammonium salts as potential MPS PET agents.     

From 3-D positron emission tomography to 3-D positron emission tomography/computed tomography: what did we learn?

The recent introduction of combined positron emission tomography (PET)/computed tomography (CT) scanners is having a far-reaching effect on the field of medical imaging by bringing functional imaging to the forefront in radiology, oncology and other specialties. The PET/CT scanner is an evolution in technology combining two well-developed imaging modalities: anatomical imaging with CT and functional imaging with PET. The first prototype PET/CT scanner was a consequence of a succession of steps that, in chronological order, included the development of the High Density Avalanche Chamber (HIDAC) PET camera, 3-D PET methodology and the rotating partial-ring tomograph (PRT). The successful completion of each step was a prerequisite to progress to the next phase, and the lessons learned could then be applied to subsequent initiatives. This review will map the milestones from 3-D PET to 3-D PET/CT and assess the role each step played in the development of PET instrumentation over the past two decades.     

Artifactual 2-deoxy-2-[(18)F]fluoro-D-glucose localization surrounding metallic objects in a PET/CT scanner using CT-based attenuation correction.

PURPOSE: To communicate a clinically important artifact in positron emission tomography (PET) images using a PET/computerized tomography (CT) scanner with CT-based attenuation correction. PROCEDURE: A 65-year-old man with a maxillary sinus squamous cell carcinoma was injected with 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) and underwent a PET scan using a dual modality PET/CT scanner with CT-based attenuation correction. Immediately afterward, the patient had a second scan using a different PET scanner that used a high-energy transmission source for attenuation correction. RESULTS: The PET/CT scanner images demonstrated a focus of activity in the attenuation corrected PET images corresponding to a pacemaker in the left chest wall. No abnormal focus was noted in the nonattenuation corrected PET images. The patient had no signs or symptoms of inflammation at the site. A second scan using a PET scanner with a high-energy transmission source demonstrated no abnormal focus in the AC PET images. CONCLUSIONS: PET/CT scanners using CT-based attenuation methodology can overcorrect dense objects resulting in hot spot artifacts in AC PET images.     

Interaction of colony-stimulating factors and fluorodeoxyglucose f(18) positron emission tomography

OBJECTIVE: To evaluate reports of altered diagnostic images with fluorodeoxyglucose F(18) (FDG) positron emission tomography (PET) after treatment with colony-stimulating factors (CSFs). DATA SOURCES: Literature was identified by a MEDLINE search (1966-December 2001). Key search terms included granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, macrophage colony-stimulating factor, fluorodeoxyglucose, and emission-computed tomography. English language literature was reviewed. DATA SYNTHESIS: Reports have suggested altered FDG PET images following CSF treatment. Studies that assessed the effect of CSF administration on FDG PET imaging of the bone and bone marrow were reviewed. CONCLUSIONS: Administration of CSFs may interfere with accurate FDG PET imaging. Separating FDG PET imaging from CSF therapy by >/=5 days may diminish this interference.     

Integrated PET/CT Fusion Imaging and Endoscopic Ultrasound in the Pre-operative Staging and Evaluation of Esophageal Cancer

Purpose  

Accurate staging of esophageal cancer (ECA) is critical in determining appropriate therapy. Endoscopic ultrasound (EUS), computed tomography (CT) and positron emission tomography (PET) scanning can be used, but limited data exists regarding the use of combined PET/CT fusion imaging and EUS in ECA staging. The objective of this study is to evaluate the role of integrated PET/CT imaging and EUS in the staging of ECA.     

PET与伽玛PET在癫痫灶定位中的应用

就正电子发射断层成像 (PET)与伽玛PET在癫痫灶定位中的应用作一介绍     

Colorectal cancer staging: comparison of whole-body PET/CT and PET/MR

Purpose

Correct staging is imperative for colorectal cancer (CRC) since it influences both prognosis and management. Several imaging methods are used for this purpose, with variable performance. Positron emission tomography–magnetic resonance (PET/MR) is an innovative imaging technique recently employed for clinical application. The present study was undertaken to compare the staging accuracy of whole-body positron emission tomography–computed tomography (PET/CT) with whole-body PET/MR in patients with both newly diagnosed and treated colorectal cancer.

Methods

Twenty-six patients, who underwent same day whole-body (WB) PET/CT and WB-PET/MR, were evaluated. PET/CT and PET/MR studies were interpreted by consensus by a radiologist and a nuclear medicine physician. Correlations with prior imaging and follow-up studies were used as the reference standard. Correct staging was compared between methods using McNemar’s Chi square test.

Results

The two methods were in agreement and correct for 18/26 (69%) patients, and in agreement and incorrect for one patient (3.8%). PET/MR and PET/CT stages for the remaining 7/26 patients (27%) were discordant, with PET/MR staging being correct in all seven cases. PET/MR significantly outperformed PET/CT overall for accurate staging (P = 0.02).

Conclusion

PET/MR outperformed PET/CT in CRC staging. PET/MR might allow accurate local and distant staging of CRC patients during both at the time of diagnosis and during follow-up.

     

Usefulness of position emission tomography/computed tomography in a case of sarcoidosis with multiorgan involvement

Sarcoidosis, a systemic inflammatory disease of unknown etiology, can affect any site in the body. A bone lesion was unexpectedly detected by fluorodeoxyglucose position emission tomography/computed tomography (FDG PET/CT) in a patient with multiorgan sarcoidosis. FDG PET/CT should be considered for the detection of clinically silent lesions of sarcoidosis.     

Performance of 2-Deoxy-2-[F-18]fluoro-<Emphasis Type="SmallCaps">d</Emphasis>-glucose Positron Emission Tomography and Integrated PET/CT in Restaged Breast Cancer Patients

PURPOSE: This study was conducted to compare the clinical stage derived from 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) positron emission tomography (PET) to that of integrated PET/computed tomography (CT) in restaged breast cancer patients. PROCEDURES: Fifty-eight female patients (age range 29-80 years, mean age +/-SD, 53.3 +/- 11.7 years) underwent PET/CT restaging for breast cancer. Two experienced nuclear medicine physicians interpreted PET images. A radiologist was added for reading PET/CT studies. A patient-based analysis was performed. Histopathological findings, correlative imaging studies, changes in number, size, and hypermetabolic activity of suspicious lesions and/or patient outcome served as standard of reference for determining the diagnostic accuracy of both modalities. RESULTS: PET staged 79.3% (46/58) of the patients correctly, overstaged seven (12.1%), and understaged five patients (8.6%). Integrated PET/CT staged 89.7% (52/58) of the patients correctly, overstaged four (6.9%), and understaged two patients (3.4%). The staging accuracy of PET/CT was not significantly better than that of PET alone (p = 0.059). Lesions exhibiting mild hypermetabolic activity, benign inflammatory lesions, and physiological variants largely explained incorrect PET findings. CONCLUSION: Integrated PET/CT only marginally improves the restaging accuracy over PET alone (p = 0.059) in breast cancer patients.     

Prognostic value of preoperative fluorodeoxyglucose positron emission tomography/computed tomography in patients with potentially resectable pancreatic cancer

Abdominal Radiology - To evaluate the prognostic value of preoperative 18-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with potentially...     

Comparison between 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography and positron emission tomography/computed tomography hardware fusion for staging of patients with lymphoma.

PURPOSE: 2-Deoxy-2-[18F]fluoro-D-Glucose positron emission tomography (FDG-PET) stages patients with Hodgkin's disease (HD) and Non-Hodgkin's lymphoma (NHL) with higher accuracy than computed tomography (CT). We sought to determine whether integrated (hardware) fused PET/CT imaging results in further improvements in staging accuracy. PROCEDURES: Seventy-three patients (age 51 +/- 17 years, 37 female, 36 male) with HD (n = 20) or NHL (n = 53) undergoing staging were studied with an integrated PET/CT system. Image findings were verified by clinical follow up, additional imaging and when available, histology. RESULTS: Thirty-four of 73 patients (46.5%) had evidence of disease and 39 were disease free as confirmed by clinical evaluation and follow-up for 41 +/- 22 weeks (n = 73), including biopsy (n = 26), and other imaging modalities (n = 52) when available. A discordant image interpretation between PET and PET/CT occurred in seven patients (10%). PET/CT correctly upstaged two and downstaged five patients. Overall staging was accurate in 93% with PET/CT and 84% with PET (P = 0.03). CONCLUSION: Lymphoma is staged with higher accuracy using PET/CT than PET alone.     

Utility of Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Patients with Fever of Unknown Origin Diagnosed as Lymphoma

Objective

To assess the efficacy of fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET)/computed tomography (CT) in the diagnosis of patients with fever of unknown origin (FUO), who were finally diagnosed as lymphoma.

Subjects and Methods

A retrospective study was performed in the First Affiliated Hospital, School of Medicine of Zhejiang University, China, from March 2009 to March 2012. The PET/CT images of consecutive patients with FUO were analyzed. Within 1 week of PET/CT scanning, additional histological tests were also performed if clinically needed.

Results

A total of 73 consecutive patients were included. Of these, 34 (47s%) had a PET/CT finding suggestive of the presence of lymphoma and 29 (85s%) had a diagnosis of confirmed lymphoma; 39 (53s%) had a PET/CT result revealing the absence of lymphoma and 4 (10s%) were diagnosed by biopsy as having lymphoma. The most frequent lymphoma diagnosis was peripheral T cell lymphoma (n = 16; 55s%), followed by diffuse large B cell lymphoma (n = 9; 31s%). The accuracy of PET/CT was 88s%.

Conclusion

In this study, PET/CT had high diagnostic accuracy in patients with FUO resulting from lymphoma, which indicated that PET/CT scanning was a valuable diagnostic tool for these groups of patients with FUO.Key Words: Fever of unknown origin, Positron emission tomography, Computed tomography, Diagnosis, Lymphoma     

Radiomics Analysis of PET and CT Components of PET/CT Imaging Integrated with Clinical Parameters: Application to Prognosis for Nasopharyngeal Carcinoma

Molecular Imaging and Biology - To investigate the prognostic performance of radiomics features, as extracted from positron emission tomography (PET) and X-ray computed tomography (CT) components...     

Clinical Value of Combined Positron Emission Tomography/Computed Tomography Imaging in the Interpretation of 2-Deoxy-2-[F-18]fluoro-<Emphasis Type="SmallCaps">d</Emphasis>-glucose–Positron Emission Tomography Studies in Cancer Patients

Background Positron emission tomography (PET)/computed tomography (CT) is a new imaging modality that provides exact coregistration of anatomic and metabolic data. We have investigated to what degree this new technique might affect the interpretation of PET images in a nonselected group of consecutive cancer patients, reflecting routine condition in a busy cancer center.Methods Whole-body 2-deoxy-2-[F-18]fluoro-d-glucose (FDG)–PET and PET/CT fusion image sets were compared in 100 consecutive, nonselected patients: 21 with head and neck cancer, 39 with chest malignancies, and 40 with malignancies of the abdomen and pelvis. All studies were performed for primary staging or evaluation of therapy and were interpreted by two nuclear medicine physicians also trained in radiology. Areas of abnormal FDG uptake were identified on PET and graded as likely benign, equivocal, or likely malignant. Positron emission tomography/computed tomography fusion images were then made available, and the initial findings were amended if necessary.Results One hundred sixty-six areas with abnormal FDG uptake were identified. Based on PET alone, 51 sites were considered equivocal for malignancy. With PET/CT, the number of equivocal lesions decreased to 24. This difference is more marked in the head and neck as well as the abdomen and pelvis. When the equivocal sites were included in the analysis and grouped with the malignant sites, positive predictive value (PPV) of PET/CT was 89% compared with 75% for PET (p = 0.04).Conclusion Combined PET/CT results in increased reader confidence and 53% fewer equivocal readings, as well as improved PPV compared with PET alone.*Contributed equally to this work.     

Diagnostic Accuracy of Ultrasound and 18-F-FDG PET or PET/CT for Patients with Suspected Recurrent Papillary Thyroid Carcinoma

The purpose of this study was to evaluate the diagnostic accuracies of ultrasound (US) and 18-F-FDG positron emission tomography (PET) or PET/computed tomography (CT) for detecting recurrent papillary thyroid carcinoma (PTC) after total thyroidectomy. Our study enrolled 76 postoperative patients who underwent both neck US and PET because of the suspicion of recurrence. The results of US and PET were correlated with the histopathology, the radioactive iodine whole body scan (WBS) or the clinical follow-up results. Among them, 53 patients had recurrent disease (local recurrence, 42; distant metastasis, 3; elevated Tg level, 8) and 23 showed no evidence of disease. From the analysis, US showed higher diagnostic accuracy, sensitivity and specificity compared with those of PET (71.1%, 71.7% and 69.6% vs. 55.3%, 56.6%, and 52.2%). PET added diagnostic information in a limited number of patients with negative results on neck US (3 with neck recurrence and 2 with distant metastasis). (E-mail: jeonghlee@hanmir.com)     

Zero-Extra-Dose PET Delayed Imaging with Data-Driven Attenuation Correction Estimation

Molecular Imaging and Biology - Delayed positron emission tomography (PET) imaging may improve sensitivity and specificity in lesion detection. We proposed a PET data-driven method to estimate the...