Diagnostic performance of fluorodeoxyglucose positron emission tomography/magnetic resonance imaging fusion images of gynecological malignant tumors: comparison with positron emission tomography/computed tomography

Purpose

We compared the diagnostic accuracy of fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and PET/magnetic resonance imaging (MRI) fusion images for gynecological malignancies.

Materials and methods

A total of 31 patients with gynecological malignancies were enrolled. FDG-PET images were fused to CT, T1- and T2-weighted images (T1WI, T2WI). PET-MRI fusion was performed semiautomatically. We performed three types of evaluation to demonstrate the usefulness of PET/MRI fusion images in comparison with that of inline PET/CT as follows: depiction of the uterus and the ovarian lesions on CT or MRI mapping images (first evaluation); additional information for lesion localization with PET and mapping images (second evaluation); and the image quality of fusion on interpretation (third evaluation).

Results

For the first evaluation, the score for T2WI (4.68 ± 0.65) was significantly higher than that for CT (3.54 ± 1.02) or T1WI (3.71 ± 0.97) (P < 0.01). For the second evaluation, the scores for the localization of FDG accumulation showing that T2WI (2.74 ± 0.57) provided significantly more additional information for the identification of anatomical sites of FDG accumulation than did CT (2.06 ± 0.68) or T1WI (2.23 ± 0.61) (P < 0.01). For the third evaluation, the three-point rating scale for the patient group as a whole demonstrated that PET/T2WI (2.72 ± 0.54) localized the lesion significantly more convincingly than PET/CT (2.23 ± 0.50) or PET/T1WI (2.29 ± 0.53) (P < 0.01).

Conclusion

PET/T2WI fusion images are superior for the detection and localization of gynecological malignancies.     

Management implications of fluorodeoxyglucose positron emission tomography/magnetic resonance in untreated intrahepatic cholangiocarcinoma

European Journal of Nuclear Medicine and Molecular Imaging - Intrahepatic cholangiocarcinoma (ICC) is associated with a poor prognosis with surgical resection offering the best chance for long-term...     

PET/MRI在肺癌中的潜在临床应用价值

PET/MRI作为新出现的融合影像技术,其临床应用价值尚未得到充分证实。与CT相比,MRI具有软组织对比分辨力高、无辐射、多参数成像、能够提供更多功能信息的优势,PET与MRI的融合对于肺癌的潜在应用价值可能要优于PET/CT。简述不同的PET/MRI系统的设计,并从肺结节的检出、鉴别诊断、TNM分期、预后/早期疗效评价/肿瘤复发4个方面介绍PET/MRI在肺癌中的潜在临床价值。     

18F-Fluoride positron emission tomography and positron emission tomography/computed tomography

(18)F-Fluoride is a positron-emitting bone-seeking agent, the uptake of which reflects blood flow and remodeling of bone. Assessment of (18)F-fluoride kinetics using quantitative positron emission tomography (PET) methods allows the regional characterization of lesions of metabolic bone diseases and the monitoring of their response to therapy. It also enables the assessment of bone viability and discrimination of uneventful and impaired healing processes of fractures, bone grafts and osteonecrosis. Taking advantage of the favorable pharmacokinetic properties of the tracer combined with the high performance of PET technology, static (18)F-fluoride PET is a highly sensitive imaging modality for detection of benign and malignant osseous abnormalities. Although (18)F-fluoride uptake mechanism corresponds to osteoblastic activity, it is also sensitive for detection of lytic and early marrow-based metastases, by identifying their accompanying reactive osteoblastic changes, even when minimal. The instant fusion of increased (18)F-fluoride uptake with morphological data of computed tomography (CT) using hybrid PET/CT systems improves the specificity of (18)F-fluoride PET in cancer patients by accurately differentiating between benign and malignant sites of uptake. The results of a few recent publications suggest that (18)F-fluoride PET/CT is a valuable modality in the diagnosis of pathological osseous conditions in patients also referred for nononcologic indications. (18)F-fluoride PET and PET/CT are, however, not widely used in clinical practice. The limited availability of (18)F-fluoride and of PET and PET/CT systems is a major factor. At present, there are not enough data on the cost-effectiveness of (18)F-fluoride PET/CT. However, it has been stated by some experts that (18)F-fluoride PET/CT is expected to replace (99m)Tc-MDP bone scintigraphy in the future.     

Quantitative myocardial perfusion imaging by cardiovascular magnetic resonance and positron emission tomography

Recent studies have demonstrated that a detailed knowledge of the extent of angiographic coronary artery disease (CAD) is not a prerequisite for clinical decision making, and the clinical management of patients with CAD is more and more focused towards the identification of myocardial ischemia and the quantification of ischemic burden. In this view, non-invasive assessment of ischemia and in particular stress imaging techniques are emerging as preferred and non-invasive options. A quantitative assessment of regional myocardial perfusion can provide an objective estimate of the severity of myocardial injury and may help clinicians to discriminate regions of the heart that are at increased risk for myocardial infarction. Positron emission tomography (PET) has established itself as the reference standard for myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) quantification. Cardiac magnetic resonance (CMR) is increasingly used to measure MBF and MPR by means of first-pass signals, with a well-defined diagnostic performance and prognostic value. The aim of this article is to review the currently available evidence on the use of both PET and CMR for quantification of MPR, with particular attention to the studies that directly compared these two diagnostic methods.     

Computer tomography, magnetic resonance imaging, and positron emission tomography or positron emission tomography/computer tomography for detection of metastatic lymph nodes in patients with ovarian cancer: a meta-analysis

Objectives

To compare the diagnostic performances of computed tomography (CT), magnetic resonance (MR) imaging, and positron emission tomography (PET or PET/CT) for detection of metastatic lymph nodes in patients with ovarian cancer.

Methods

Relevant studies were identified with MEDLINE and EMBASE from January 1990 to July 2010. We estimated the weighted summary sensitivities, specificities, OR (odds ratio), and summary receiver operating characteristic (sROC) curves of each imaging technique and conducted pair-wise comparisons using the two-sample Z-test. Meta-regression, subgroup analysis, and funnel plots were also performed to explain the between-study heterogeneity.

Results

Eighteen eligible studies were included, with a total of 882 patients. PET or PET/CT was a more accurate modality (sensitivity, 73.2%; specificity, 96.7%; OR [odds ratio], 90.32). No significant difference was detected between CT (sensitivity, 42.6%; specificity, 95.0%; OR, 19.87) and MR imaging (sensitivity, 54.7%; specificity, 88.3%; OR, 12.38). Meta-regression analyses and subgroup analyses revealed no statistical difference. Funnel plots with marked asymmetry suggested a publication bias.

Conclusion

FDG-PET or FDG-PET/CT is more accurate than CT and MR imaging in the detection of lymph node metastasis in patients with ovarian cancer.     

Age-related structural and functional changes in the breast: multimodality correlation with digital mammography, computed tomography, magnetic resonance imaging, and positron emission tomography

Preliminary results generated from digital mammography, computed tomography, magnetic resonance imaging, and (18)F-fluorodeoxyglucose positron emission tomography demonstrate concordant findings of decreasing glandular tissue and decreasing metabolic activity with increasing age. These results are presented in the context of a detailed literature review summarizing age-related changes in the breast, both from the histologic/physiologic and the imaging perspectives. We also discuss potential applications of this approach and emphasize the importance of new advanced imaging technologies to offer high levels of quantitative precision for tissue characterization for research and clinical purposes.     

Stroke volume measurements with first-pass dynamic positron emission tomography: Comparison with cardiovascular magnetic resonance

Background  The assessment of forward stroke volume (SV) using dynamic, first-pass cardiac positron emission tomography (PET) was shown to be feasible in a limited number of studies with small numbers of subjects. The aim of this study was to compare first-pass derived SV with cardiovascular magnetic resonance imaging (CMR)-obtained values in a larger population of subjects. Methods and Results  Fifty-nine subjects with varying degrees of cardiac function were studied. Stroke volume was assessed using oxygen-15-labeled water (H₂ ¹⁵O) dynamic first-pass PET for both the right ventricle (RV) and left ventricle (LV), and compared with the findings of aorta velocity-encoded phase-contrast CMR. The PET-estimated SV was higher for the RV than for the LV (133±34 vs 116±31 mL, P<.01, ±SD), and both were higher compared with values obtained by CMR (81±20 mL, both P<.01,±SD). Although significant, the correlations between PET and CMR were moderate for both the RV (r=0.37, P<.01) and the LV (r=0.40, P<.01,±SD). Bland-Altman analysis revealed a progressive overestimation with increasing SV measured in either ventricle. Conclusions  First-pass dynamic H₂ ¹⁵O PET for the assessment of forward SV is feasible, although values are progressively overestimated with increasing SV, particularly when the RV is used, and correlations with aorta velocity-encoded phase-contrast CMR are moderate. These findings are probably protocol-dependent and warrant further study before the use of first-pass dynamic H₂ ¹⁵O PET in clinical or research settings can be advocated.     

Diagnostic efficacy of bone scintigraphy, magnetic resonance imaging, and positron emission tomography in bone metastases of myxoid liposarcoma

Myxoid liposarcomas (MLS) have a tendency to metastasize to unusual sites. We report an unusual case of bone metastases not detected by bone scan and neither by fluorodeoxyglucose positron emission tomography (PET-FDG) and successfully identified with magnetic resonance imaging (MRI) in a patient with metachronic MLS. Histopathological examination of the primary tumor evidenced a tumor with unfavorable prognostic markers, and the biopsy of an iliac bone lesion confirmed the diagnosis of metastatic disease. On histological grounds, the tumor showed features of a more differentiated neoplasm without foci of round cells or necrosis in the latter. MRI allowed the identification of disseminated disease compared to computed tomography (CT) and PET scans. Thus, because of the heterogeneous histological features of MLS and the biological behavior of the disease, a combined approach of FDGPET-CT and MRI, may allow a more accurate staging of soft tissue sarcomas.     

Simultaneous whole body 18F-fluorodeoxyglucose positron emission tomography magnetic resonance imaging for evaluation of pediatric cancer: Preliminary experience and comparison with 18F-fluorodeoxyglucose positron emission tomography computed tomography

AIM: To describe our preliminary experience with simultaneous whole body ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography and magnetic resonance imaging (PET-MRI) in the evaluation of pediatric oncology patients.METHODS: This prospective, observational, single-center study was Health Insurance Portability and Accountability Act-compliant, and institutional review board approved. To be eligible, a patient was required to: (1) have a known or suspected cancer diagnosis; (2) be under the care of a pediatric hematologist/oncologist; and (3) be scheduled for clinically indicated ¹⁸F-FDG positron emission tomography-computed tomography (PET-CT) examination at our institution. Patients underwent PET-CT followed by PET-MRI on the same day. PET-CT examinations were performed using standard department protocols. PET-MRI studies were acquired with an integrated 3 Tesla PET-MRI scanner using whole body T1 Dixon, T2 HASTE, EPI diffusion-weighted imaging (DWI) and STIR sequences. No additional radiotracer was given for the PET-MRI examination. Both PET-CT and PET-MRI examinations were reviewed by consensus by two study personnel. Test performance characteristics of PET-MRI, for the detection of malignant lesions, including FDG maximum standardized uptake value (SUVmax) and minimum apparent diffusion coefficient (ADCmin), were calculated on a per lesion basis using PET-CT as a reference standard.RESULTS: A total of 10 whole body PET-MRI exams were performed in 7 pediatric oncology patients. The mean patient age was 16.1 years (range 12-19 years) including 6 males and 1 female. A total of 20 malignant and 21 benign lesions were identified on PET-CT. PET-MRI SUVmax had excellent correlation with PET-CT SUVmax for both benign and malignant lesions (R = 0.93). PET-MRI SUVmax > 2.5 had 100% accuracy for discriminating benign from malignant lesions using PET-CT reference. Whole body DWI was also evaluated: the mean ADCmin of malignant lesions (780.2 + 326.6) was significantly lower than that of benign lesions (1246.2 + 417.3; P = 0.0003; Student’s t test). A range of ADCmin thresholds for malignancy were evaluated, from 0.5-1.5 × 10^-3 mm²/s. The 1.0 × 10^-3 ADCmin threshold performed best compared with PET-CT reference (68.3% accuracy). However, the accuracy of PET-MRI SUVmax was significantly better than ADCmin for detecting malignant lesions compared with PET-CT reference (P < 0.0001; two-tailed McNemar’s test).CONCLUSION: These results suggest a clinical role for simultaneous whole body PET-MRI in evaluating pediatric cancer patients.     

肺癌的MR全身DWI与PET成像的对照研究

目的：探讨MR DWI及PET成像在肺癌诊断及鉴别诊断中的应用价值。方法：26例临床高度怀疑为肺癌且接受了PET检查的患者行MR DWI检查,通过三维图像重组及黑白翻转技术,得到＂类PET＂图像,观察病变的形态、大小和分布,并与PET影像进行比较,在工作站上测量肺部病变的ADC值及SUV值,进行相关性分析。最终的诊断结果依据影像学检查、病理诊断和随访复查共同确定,其中肺癌19例,肺部炎性假瘤1例,慢性炎症4例,淋巴结反应性增生2例。结果：以病理结果为金标准,PET检出肺癌的敏感度为100%,特异度为57.1%;MR DWI的敏感度为94.7%,特异度为71.2%。肺癌与炎性病变的ADC值及SUV值差异均有统计学意义（P〈0.01）,肺癌病灶的ADC值与SUV值没有明显线性相关关系（r=-0.293,P〉0.05）。结论：MR DWI及PET成像对肺癌的诊断有较高的敏感度及特异度,两种方法互为补充,可为肺癌的诊断及鉴别诊断提供更多的信息。     

Cardiac metabolism: A technical spectrum of modalities including positron emission tomography,single-photon emission computed tomography,and magnetic resonance spectroscopy

Noninvasive techniques for the assessment of cardiac metabolism are important for the detection of potentially salvageable tissue in jeopardized areas of the myocardium. The correct identification of hibernating and stunned myocardium in patients with severely depressed cardiac function can have vital therapeutic consequences for the patient. Changes in myocardial fatty acid and glucose metabolism during acute and prolonged ischemia can be traced by positron-emitting or gamma-emitting radiopharmaceuticals. Alternatively,³¹P-labeled magnetic resonance spectroscopy can be used for the assessment of high-energy phosphate metabolism. It is not yet clear which modality will emerge as the most useful in the clinical setting. Positron emission tomography (PET) that uses combinations of flow tracers and metabolic tracers offers unique opportunities for quantification and high-resolution static and rapid dynamic studies. Currently, assessment of glucose metabolism with¹⁸F-fluorodeoxyglucose is regarded as the gold standard for myocardial viability and prediction of improvement of impaired contractile function after revascularization. However, preserved oxidative metabolism may be required for potential functional improvement, and therefore assessment of residual oxidative metabolism by¹¹C-labeled acetate PET may prove to be more accurate than¹⁸F-fluorodeoxyglucose PET, which reflects both anaerobic and oxidative metabolism. Moreover, because fatty acids are metabolized only aerobically, they are excellent candidates for the clinical assessment of myocardial viability and prediction of functional improvement after revascularization. Especially derivatives of fatty acids that are not metabolized but accumulate in the myocyte are attractive for myocardial imaging. Examples are¹²³I-beta-methyl-p-iodophenyl pentadecanoic acid and 15-(o-¹²³I-phenyl)-pentadecanoic acid. These tracers can be detected by planar scintigraphy and single-photon emission computed tomography, which are more economical and widely available than PET. In addition, 511 keV collimators have been developed recently, making the detection of positron emitters by planar scintigraphy and single-photon emission computed tomography feasible. The experience with³¹P-labeled magnetic resonance spectroscopy in humans is still limited. With current magnetic resonance spectroscopic techniques, insufficient spatial resolution is achieved for clinical purposes, but the possibility of serial measurements to monitor rapid changes of phosphate-containing molecules in time makes magnetic resonance spectroscopy very valuable for the research of myocardial metabolism.     

Temporal lobe epilepsy: Correlation of proton magnetic resonance spectroscopy and 18F-fluorodeoxyglucose positron emission tomography

Proton magnetic resonance spectroscopy (MRS) has demonstrated reduction of N-acetylaspartate (NAA) in the epileptogenic temporal lobe. However, the correlation of NAA reduction with cerebral metabolic abnormalities is unknown in temporal lobe epilepsy (TLE). Proton MRS and ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG/PET) were used to study 12 unilateral TLE patients with medically intractable seizures and 26 age-matched healthy volunteers. The epileptogenic temporal lobe of each patient was determined by both electroencephalography and FDG/PET. The NAA/choline-plus-creatine (NAA/(Cho+Cr)) ratio correlated significantly with the interictal glucose metabolism (r = 0.54, P 0.01) in 12 TLE patients. The mean NAA/(Cho + Cr) ratio in the epileptogenic temporal lobe was significantly less than that in the contralateral side (P < 0.01), and less than that in normal control temporal lobes (P < 0.0001). These results suggest that quantitative MRS abnormalities reflect underlying metabolic pathology in TLE.     

Computed tomography, magnetic resonance imaging and 11C-metomidate positron emission tomography for evaluation of adrenal incidentalomas

Background

Given the higher sensitivity of modern computed tomography (CT) scanners, adrenal incidentalomas are being discovered increasingly often. This implies a growing quantitative diagnostic and clinical problem. CT and/or magnetic resonance imaging (MRI) and usually thorough hormonal testing are routinely used to determine the origin of these lesions. Recently, positron emission tomography (PET) using the tracer ¹¹C-metomidate (MTO) has been established as an alternative diagnostic method with high sensitivity for identifying adrenocortical lesions. The aim of this study was to evaluate the clinical use and value of MTO-PET compared to CT and MRI in the characterisation and work-up of adrenal incidentalomas.

Methods

Initially, we retrospectively evaluated 20 adrenal incidentalomas in patients who had undergone CT, MRI and MTO-PET and from whom we had either histopathological diagnosis or clinical follow-up data. After this analysis we conducted a prospective study in order to compare the imaging modalities. In the latter study, 24 incidentalomas were imaged by CT, MRI and MTO-PET and the results were correlated to those from histopathology (n = 8) and clinical diagnosis after follow-up (n = 16).

Results

In the retrospective analysis, MRI and especially MTO-PET, correlated well to histopathology and clinical diagnosis after follow-up, whereas specificity with CT was low. This was possibly due to the presence of several haematomas/fibrosis which were misdiagnosed as adrenocortical adenomas. In the prospective cohort, sensitivity and specificity with CT were 0.71 and 1.0, respectively, and further characterisation by MRI increased these values to 0.86 and 1.0, whereas maximum sensitivity and specificity were reached when MTO-PET was added.

Conclusion

The diagnosis of an adrenocortical adenoma may be established by CT in most patients and by MRI in an additional number. For the few remaining patients needing further characterisation, MTO-PET is advantageous as an additional imaging modality.     

Recurrent ovarian endodermal sinus tumor: demonstration by computed tomography,magnetic resonance imaging,and positron emission tomography

We report a case of recurrent endodermal sinus tumor.of the ovary that was identified and/or clearly depicted by computed tomography, magnetic resonance imaging, and positron emission tomography. The potential roles of various imaging modalities in the detection of recurrent endodermal sinus tumor are discussed.