Using 18-fluoro-2-deoxyglucose positron emission tomography in detecting infectious endocarditis/endoarteritis: a preliminary report

RATIONALE AND OBJECTIVES: We evaluated the effectiveness of positron emission tomography (PET) with 18-fluoro-2-deoxyglucose (FDG) in the detection of infectious endocarditis/endoarteritis. MATERIALS AND METHODS: For this study, we recruited 6 patients (4 women, 2 men; age range, 35 - 78 years; mean age, 55.8 +/- 16.8 years) who were clinically diagnosed as having infective endocarditis/endoarteritis by their echocardiographic findings and by Duke criteria. RESULTS: For all 6 patients, we also found increased FDG uptakes in the corresponding areas detected in echocardiography. CONCLUSION: FDG-PET appears to be a promising tool in diagnosing infective endocarditis/endoarteritis, and further prospective studies on a large scale to fully exploit the usefulness of FDG-PET for infective endocarditis/endoarteritis are needed.     

Ability of 18-fludeoxyglucose positron emission tomography/CT to detect incidental cancer

Objective:

To determine the prevalence and clinical features of pathologically proven incidental cancer (IC) detected by whole-body fluorine-18 fludeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/CT, as well as the incidence of false-positive and false-negative results.

Methods:

We retrospectively reviewed reports derived from ¹⁸F-FDG PET/CT images of 3079 consecutive patients with known or suspected malignancies for 3 years. Discrete focal uptake indicating IC was identified from reports as well as pathological or clinical diagnoses, and the clinical courses were investigated. The false-positive result was defined as uptake indicating IC but not pathologically confirmed as malignant during follow-up. The false-negative result was defined as pathologically proven IC detected by another modality at initial clinical work-up or diagnosed during the follow-up period.

Results:

We found ¹⁸F-FDG uptake indicating IC in 6.7% of all patients, and IC was pathologically proven in 2.2% of all patients. The most common sites were the colon, lung and stomach. The median survival duration of patients with IC was 42 months. The results were false positive in 4.5% of all patients, and the results were false negative in 2.3% of all patients.

Conclusion:

¹⁸F-FDG PET/CT is a valuable tool for detecting IC. The rates of false-positive and false-negative results are within acceptable range.

Advances in knowledge:

This is the first report to describe the survival of patients with IC, and the detailed features of false-negative results at actual clinical settings.Integrated whole-body positron emission tomography (PET)/CT using the glucose analogue fluorine-18 fludeoxyglucose (¹⁸F-FDG) is an established modality for oncologic imaging. Combined metabolic and morphological images yielded by ¹⁸F-FDG PET/CT can provide accurate information on the staging, restaging and therapeutic monitoring of many common cancers.¹ Furthermore, ¹⁸F-FDG PET and PET/CT have the potential for cancer screening. Owing to the non-specific nature of ¹⁸F-FDG uptake, a wide range of malignant tumours can be visualized as incidental foci of hypermetabolism. For instance, new malignant tumours have been detected in asymptomatic individuals,² patients with head and neck cancer,³ oesophageal cancer⁴ and malignant lymphoma.⁵ Incidental focal ¹⁸F-FDG uptake within the gastrointestinal tract frequently represents malignant and pre-malignant tumours.^6,7 The detection of incidental cancer (IC) significantly impacts clinical oncological practice. Namely, the detection of a primary cancer can lead a patient to a new treatment, and the detection of a second primary cancer can lead a patient to a more suitable treatment.IC has been detected by ¹⁸F-FDG PET or PET/CT in the past decade.^8–15 8–13 The detection rate of IC ranges from 0.9% to 4.4%,^8–15 and a few reports have described a wider range (0.1–4.4%) of false-negative findings.^13–15 However, the survival of patients with IC has not been detailed. Differences in detection rates and other findings arise owing to many factors, including country, age, symptomatic or asymptomatic individuals, ¹⁸F-FDG PET or PET/CT, judgment criteria, method and period of follow-up.

Table 1.

Previous studies evaluating detection rate of incidental cancer (IC)

Prevalence and risk of cancer of incidental uptake in prostate identified by fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography

ObjectiveThe objective was to investigate the prevalence of incidental fluorine-18 fluorodeoxyglucose (FDG) uptake in positron emission tomography/computed tomography.MethodsA total of 11,239 male nonprostate disease patients were included retrospectively.ResultsThe prevalence of incidental prostate FDG uptake was approximately 1.8%. Among 198 incidental lesions, 100 patients had further examinations; 20 lesions were confirmed to be malignant, while 80 lesions were benign. After logistic regression analysis, age, site, and the maximum standard uptake value were the potent predictors for differentiation of malignant prostate lesions.ConclusionWhen focal FDG uptake in the peripheral zone of prostate is detected, especially in elderly men, further clinical evaluation is recommended.     

Hepatocellular carcinoma tumour thrombus in a re-canalised para-umbilical vein: detection by 18-fluoro-2-deoxyglucose positron emission tomography imaging

This case report describes an unusual site of tumour thrombus in a re-canalised para-umbilical vein, in a patient with hepatocellular carcinoma (HCC) and cirrhosis. The tumour thrombus was suspected on conventional radiography and confirmed using PET imaging, illustrating the complimentary value of structural and functional imaging in achieving the correct diagnosis.     

18F-FDGPET／CT偶发直结肠局灶性高代谢灶良恶性判断价值

目的：探讨PET/CT意外发现直结肠FDG局灶性高代谢灶的临床意义。方法回顾性分析34例PET/CT意外探测到直结肠局灶性高放射性摄取灶的病例,半定量分析局部病灶放射性摄取程度,均在1个月内行结肠镜检查,对表现为新生肿物病灶进行手术切除并做病理分析,将肠镜及病理结果作为金标准。所有临床资料及半定量分析数据汇总后行单因素方差分析。结果在所有34例结肠局灶性FDG高代谢病灶中,结肠镜及病理检查出恶性及癌前病变共22例,阳性预测值（PPV）为64．7％。其中8例为腺瘤,病灶SUVmax平均值为7．55±2．1,14例恶性病灶（9例腺癌,卵巢癌转移2例,间皮瘤转移2例,交界瘤转移1例）,SUVmax平均值为7．62±4．87。结肠炎性改变4例（11．8％）,SUV-max平均值为9．35±4．9,肠镜正常8例（23．5％）,SUVmax平均值为7．4±1．75。癌前病变、恶性肿瘤、炎性病变及生理性摄取组间的单因素方差分析提示各组间无显著性差异,F＝0．27,P＝0．84,其中癌前病变组与恶性病灶组无显著性差异,P＝0．968。结论18F-FDGPET/CT偶然发现直结肠局灶性高摄取病灶中癌前病变和恶性病变阳性率很高,单纯依靠SUVmax,不能进行良恶性鉴别,因此进一步结肠镜检查是有临床意义的。     

F-18-fluoro-2-deoxyglucose positron emission tomography/computed tomography in the follow-up of breast cancer with elevated levels of tumor markers

OBJECTIVE: The value of combined positron emission tomography (PET)/computed tomography (CT) in the follow-up of patients with breast cancer with elevated tumor markers but without proven metastases or local recurrence was assessed. METHODS: Thirty-four women underwent PET/CT. The PET and CT images were first analyzed separately; fused findings were then interpreted, blinded to the results of the other modalities. The results of CT, PET, and PET/CT were compared with each other and correlated to the final diagnosis. RESULTS: The PET/CT identified 149 malignant foci in 24 patients (71%). The CT detected 96 of these foci in 18 patients, whereas PET identified 124 foci in 17 patients. Differences between CT and PET were not significant. Differences between PET/CT and CT (P < 0.01) and PET/CT and PET (P < 0.01) were significant. The person-based sensitivity of PET/CT, PET, and CT was 96%, 88% and 96%, respectively. Specificity of PET/CT, PET, and CT was 89%, 78%, and 78%, respectively. CONCLUSIONS: The PET/CT is a valuable modality for the follow-up of patients with breast cancer and elevated levels of tumor markers.     

Anatomical adjustments in brain positron emission tomography using CT images

We have developed a method that allows us to place regions of interest on X-ray CT (XCT) images that are automatically adjusted to positron emission tomography (PET) images from the same patient. A face mask with landmarks was used during PET and XCT studies for matching slice positions between PET and XCT. Anatomical locations in different images of the same slice can be accurately adjusted using the landmarks and a video system. In our clinical experience misadjustments of the slice position are on the average less than 2 mm in axial distance and 1.0 degrees in slice angle. The method is easily applicable to any PET or XCT device.     

Multicentre study of 18F-FDG-PET/CT prostate incidental uptake

Aim

The purpose of our study was to establish the prevalence and pathological nature of fluorine-18-fluorodeoxyglucose (18F-FDG) prostate incidental uptake (PIU) among patients studied for non-prostate-malignant purposes in three nuclear medicine centres.

Methods

We retrospectively evaluated 20,422 scans performed on male patients; all patients underwent 18F-FDG-PET/CT for purposes not related to prostate disease.

Results

Among 20,422 patients PIU was identified for 280 (1.4 %) with an average age of 70 ± 10.7 years. Sixty-three of the 280 patients with PIU (22.5 %) underwent PSA dosage and biopsy to determine the nature of the incidental uptake. Thirty-five of the 63 (55.5 %) PIU were malignant whereas 28/63 (44.5 %) were benign. The average value of PSA for patients with benign PIU was 3.7 ± 2.8 ng/ml whereas it was 7.8 ± 8.2 ng/ml in patients with malignant PIU; this difference was statistically significant. For malignant lesions, the average lesion-to-liver SUVmax ratio was 2.9 ± 2.5 and the average lesion-to-blood-pool SUVmax ratio was 3.7 ± 2.5. For benign lesions, the average lesion-to-liver SUVmax ratio was 2.5 ± 1.7 and the average lesion-to-blood-pool SUVmax ratio was 3.5 ± 2.4; there was no statistically significant difference between lesion-to-liver and lesion-to-blood-pool SUVmax ratios for benign and malignant lesions.

Conclusion

Because PIU values are indicative of malignancy for a substantial percentage of patients, further investigation is required.

     

Myocardial imaging with 18F-fluoro-2-deoxyglucose positron emission tomography and magnetic resonance imaging in sarcoidosis

Purpose Despite accumulating reports on the clinical value of ¹⁸F-fluoro-2-deoxyglucose positron emission tomography (¹⁸F-FDG PET) and magnetic resonance imaging (MRI) in the assessment of cardiac sarcoidosis, no studies have systematically compared the images of these modalities. Methods Twenty-one consecutive patients with suspected cardiac sarcoidosis underwent cardiac examinations that included ¹⁸F-FDG PET and MRI. The association of ¹⁸F-FDG PET and MRI findings with blood sampling data such as serum angiotensin converting enzyme levels was also evaluated. Results Eight of 21 patients were diagnosed as having cardiac sarcoidosis according to the Japanese Ministry of Health and Welfare Guidelines for Diagnosing Cardiac Sarcoidosis. Sensitivity and specificity for diagnosing cardiac sarcoidosis were 87.5 and 38.5%, respectively, for ¹⁸F-FDG PET, and 75 and 76.9%, respectively, for MRI. When the ¹⁸F-FDG PET and MRI images were compared, 16 of 21 patients showed positive findings in one (n = 8) or both (n = 8) of the two modalities. In eight patients with positive findings on both images, the distribution of the findings differed among all eight cases. The presence of positive findings on ¹⁸F-FDG PET was associated with elevated serum angiotensin-converting enzyme levels; this association was not demonstrated on MRI. Conclusions Both ¹⁸F-FDG PET and MRI provided high sensitivity for diagnosing cardiac sarcoidosis in patients with suspected cardiac involvement, but the specificity of ¹⁸F-FDG PET was not as high as previously reported. The different distributions of the findings in the two modalities suggest the potential of ¹⁸F-FDG PET and MRI in detecting different pathological processes in the heart.     

肺部单发结节在~(18)氟脱氧葡萄糖-正电子发射体层显像检查后外科决策

目的探讨肺部单发结节(SPN)患者在18氟脱氧葡萄糖-正电子发射体层显像(FDG-PET)检查后的外科决策。方法 1998年10月—2006年4月对375例直径1.0～3.0 cm的SPN患者行FDG-PET检查,采用目测法结合半定量分析判读。结果 FDG-PET定性诊断的敏感度、特异度、准确率分别为73.7%(188/255)、71.7%(86/120)、73.1%(274/375);FDG-PET无法区别良性显影病变与腺癌;对于肺外病灶FDG-PET也存在假阳性。结论 PET检查阳性的SPN,除非抗感染或抗结核治疗有效,否则都应当通过手术切除等途径确诊;对PET检查阴性的SPN患者,或手术切除,或定期随访。     

Significance of 18F-2-deoxy-2-fluoro-glucose accumulation in the stomach on positron emission tomography

Objective  To explain the accumulation of ¹⁸F-2-deoxy-2-fluoro-glucose (¹⁸FDG) on positron emission tomography (PET) in the stomach and differences in its pattern, we focus on the accumulation pattern in association with endoscopic findings of the gastric mucosa and Helicobacter pylori (Hp) infection. Methods  Of 599 cases undergoing ¹⁸FDG-PET examinations, we retrospectively analyzed the pattern of ¹⁸FDG accumulation in the stomach, findings of upper gastrointestinal endoscopy, and Hp infection. The pattern of ¹⁸FDG accumulation was classified into three groups: localized accumulation only in the fornix (Group A, 32 patients), diffuse accumulation throughout the entire stomach (Group B, 49 patients), and no accumulation (Group C, 191 patients). Results  Regarding the relation between Hp infection and ¹⁸FDG accumulation, Hp infection was positive in 56.3% of Group A, 73.5% of Group B, and 24.1% of Group C, with significant differences (p < 0.001). Regarding the relation between ¹⁸FDG accumulation and gastric mucosal inflammation, when Groups A and B were compared with Group C, nearly half of the cases in the former groups had papular redness with a significantly higher frequency of redness and erosion. Three cases found to have malignant tumor were limited to the former groups. One MALT lymphoma case was also found in the same group. Accumulation of ¹⁸FDG largely corresponded to mucosal inflammation including superficial gastritis and erosive gastritis, and therefore the main cause of non-specific ¹⁸FDG accumulation was considered to be inflammatory mucosa (mainly redness). The accumulation pattern was not associated with atrophic changes of the gastric mucosa or with Hp infection, but with mucosal inflammatory changes, including redness and erosion localized to the fornix. Conclusions  Accumulation of ¹⁸FDG in the stomach suggests a high probability of the presence of inflammatory change in the gastric mucosa forming a background for the development of cancer or malignant lymphoma, and thus requires further endoscopic examinations.     

Fluorine-18 deoxyglucose uptake in sarcoidosis measured with positron emission tomography

Regional pulmonary glucose metabolism (MR_glu; mol h^–1 g^–1), extravascular lung density (D_EV; g cm^–3) and vascular volume (V_B; ml cm^–3) were measured in a single midthoracic transaxial slice (2 cm thick) using positron emission tomography (PET) in seven patients with histologically proven sarcoidosis. The measurements were repeated 1–7 months later after steroid therapy (in two cases, no treatment) in order to assess MR_glu as an index of inflammation and relate it to routine pulmonary function tests, chest radiography and serum angiotensin converting enzyme (SACE) levels. MR^glu was computed from serial lung scans and peripheral venous blood samples for 60 min following an i.v. injection of¹⁸F-2-fluoro-2-deoxy-D-glucose (¹⁸FDG). Both MR_gu (which was increased in six of seven patients) and elevated SACE levels returned to normal in those patients treated with high-dose steroids. Regional vascular volume was normal in six of seven cases and did not change significantly with therapy. The high tissue density measured in all patients decreased significantly in two of three patients treated with 40 mg prednisolone daily. The abnormal MR& observed in active sarcoidosis becomes normal pari passu with SACE levels during high-dose steroid therapy. We conclude that MR^glu measured with¹⁸FDG and PET may reflect disease activity in sarcoidosis in quantitative terms (per gram lung tissue) and in respect of disease distribution.     

Dynamic 18F-fluorodeoxyglucose positron emission tomography/CT in hibernoma: Enhanced tracer uptake mimicking liposarcoma

We report on two cases of patients with fat-equivalent masses in computed tomography (CT), referred to our department for dynamic positron emission tomography/CT (dPET/CT) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) in order to investigate their dignity. Both qualitative and quantitative information, as derived from dPET/CTs, couldn’t exclude a high-grade liposarcoma: Visual evaluation, revealed a large hypermetabolic focus of intense ¹⁸F-FDG uptake in each patient (average SUVs 8.3 and 11.3). Regression-based parametric imaging demonstrated an enhanced distribution volume, which correlates to perfusion, and a high phosphorylation rate that correlates to cell viability. Kinetic analysis, based on a two-tissue compartment model demonstrated an enhanced FDG transport k₁ and an enhanced phosphorylation rate k₃. A non-compartmental approach based on fractal dimension revealed also enhanced values. However, final diagnosis was based on biopsy, which revealed hibernoma, a benign brown fat tumor. Brown adipose contains increased numbers of mitochondria and a high-rate of glucose metabolism. Therefore, they have increased FDG uptake. The evaluation of lipomatous lesions on CT, with high FDG uptake, should include the possibility of hibernoma as a differential diagnosis.     

Clinical significance of thyroid uptake on F18-fluorodeoxyglucose positron emission tomography

Significant uptake of the thyroid is often identified as an incidental finding on whole-body F18-fluorodeoxyglucose positron emission tomography (FDG-PET) for non-thyroid disease. Sometimes, it is a dilemma for radiologists to interpret clinical significance of thyroid uptake and give adequate recommendation for further evaluation. In general, diffuse uptake of the thyroid glands on FDG-PET is considered to be benign and very likely secondary to thyroiditis and/or hypothyroidism; a further correlation or investigation of the thyroid function and/or ultrasound is helpful. Focal uptake of the thyroid on FDG-PET is defined as an incidentaloma, which is more clinically significant owing to its high risk of malignancy ranging 25–50%. Although maximum standardized uptake value and corresponding computed tomographic finding may help to differentiate benign from malignant lesion, a cytological diagnosis is often advised. The clinical significance of diffuse plus focal uptake of the thyroid on FDG-PET is not well known; it may also be associated with an increased risk of malignancy when compared with a diffuse uptake pattern only.     

2-[18F]-fluoro-2-desoxy-D-glucose positron emission tomography initial staging impacts on survival in Hodgkin lymphoma

AIM: To assess the prognostic value and risk classification improvement of metabolic staging (MS) with Initial 2-[18F]-fluoro-2-desoxy-D-glucose positron emission tomography (FDG-PET) in initial staging of Hodgkin’s Lymphoma (HL) patients to predict 5 years overall survival (5y-OS) and event free survival (EFS).METHODS: A total of 275 patients were included in this retrospective study, 155 patients were staged with conventional anatomical staging (AS), and 120 also submitted to MS (FDG-PET). Prognostic analysis compared 5y-OS and 5y-EFS of patients staged with AS and MS. Risk-adjusted models incorporated clinical risk factors, computed tomography and FDG-PET staging.RESULTS: During the follow up of 267 evaluated patients, 220 (122 AS and 98 MS) achieved complete remission after first-line therapy (median follow-up: 70 ± 29 mo), treatment failure occurred in 79 patients and 34 died. The 5y-EFS for early vs advanced disease in AS patients was 79.3% and 66.7%, and 85.6% and 53.6% in MS patients, respectively (P < 0.01). The 5y-OS for early and advanced disease with AS was 91.3% and 81.5%, and 97.5% and 80.7% for patients staged with MS, respectively. Cox proportional hazards analysis demonstrated that FDG-PET added significant prognostic information and improved risk prediction (P = 0.02).CONCLUSION: Initial staging FDG-PET could be used as an accurate and independent predictor of OS and EFS in HL, with impact in 5y-EFS and OS.     

Quantitative fluorine 18 deoxyglucose uptake by myocardial positron emission tomography in rats

BACKGROUND: In vivo quantitative assessment of positron emission tomography (PET) with 2-deoxy-2-[fluorine 18]fluorodeoxyglucose (FDG) for rat heart has not been explored because of the theoretical limitation of spatial resolution. Our objective was to assess whether FDG uptake measured by PET is correlated with tissue radioactivity of FDG in rat heart directly measured by an automated gamma counter. METHODS AND RESULTS: Ten Sprague-Dawley rats were used for echocardiographic assessment and FDG-PET. Rats were sacrificed immediately after PET scanning, and the radioactivity of FDG in 4 segmental tissue samples of the middle transverse section was measured. Quantitative PET values in a total of 40 regions of interest, in which partial volume effect was corrected based on the phantom study and wall thickness obtained by echocardiogram, were compared with radioactivity of the corresponding 40 tissue samples. Linear regression analysis revealed that tissue radioactivity of FDG was well correlated with the quantitative PET value (Y = 1.17X; r = 0.985, P <.0001). CONCLUSIONS: Quantitative FDG-PET for rat heart is a reliable approach for assessing glucose metabolism in vivo after correction is made for partial volume effect. These results can be used for various models of heart disease with repeated studies over the disease process in the same animal.     

Cancer treatment monitoring with fluorine-18 2-fluoro-2-deoxy-d-glucose and positron emission tomography: frustration or future

Offprint requests to: H. Minn     

Fluorine-18 fluoro-2-deoxyglucose positron emission tomography in recurrent rectal cancer: relation to tumour size and cellularity

The aim of this study was to assess the value of fluorine-18 fluoro-2-deoxyglucose (FDG) positron emission tomography in patients with recurrent rectal cancer, in relation to tumour size and cellularity. Thirty-seven patients (21 mean and 16 women; mean age, 55.4±9.58 years) with suspected recurrence of rectal cancer were studied. FDG uptake was quantified by the differential absorption ratio (DAR). In 29 patients magnetic resonance imaging was also performed. To evaluate the signal intensity of the lesion, the lesion to muscle signal intensity ratios (SIR) were calculated on T2-weighted images. In seven patients who received surgical treatment the DAR and SIR were compared with the tumour cellularity. All 32 patients with confirmed recurrence showed increased FDG accumulation in the mass (DAR=4.57±1.89) in comparison with low FDG accumulation in five patients with scar (DAR=1.17±0.43). There was a significant correlation (r=0.661,P<0.001) between the DAR and the tumour diameter. There was no correlation between the DAR and SIR, whereas there was a significant correlation (r=0.565,P<0.01) between the DAR corrected using count recovery coefficient (DAR^*) and SIR. In the histopathological findings there was a tendency for the DAR^* and SIR to correlate with tumour cellularity. It is concluded that the DAR of recurrent rectal cancer should be evaluated taking into consideration the tumour size and cellularity.