Evaluation of 18F-FDG uptake and arterial wall calcifications using 18F-FDG PET/CT.

Glucose metabolic activity expressed as (18)F-FDG uptake may be increased in active atherosclerotic plaque. Calcium depositions are often increased in mature atherosclerotic plaque. The purpose of the present study was to assess the patterns of vascular-wall (18)F-FDG uptake and CT calcifications using combined PET/CT. METHODS: One hundred twenty-two consecutive patients over the age of 50 (47 women and 75 men; mean age, 66 +/- 9 y) undergoing whole-body (18)F-FDG PET/CT for tumor assessment were retrospectively evaluated. PET, CT, and PET/CT slices were generated for review. Abnormal vascular findings in major arteries in the chest and abdomen were categorized as PET positive (PET+), PET negative (PET-), CT positive (CT+), or CT negative (CT-). The topographic relationship between increased vascular-wall (18)F-FDG uptake on PET and the presence of calcifications on CT was assessed on PET/CT fused images, with abnormal sites further classified as PET+/CT+, PET+/CT-, or PET-/CT+. The presence of CT calcifications and increased vascular-wall (18)F-FDG uptake was correlated with age, sex, presence of cardiovascular risk factors, and cardiovascular disease. RESULTS: Abnormal findings were identified at 349 sites. CT calcifications (CT+) were observed at 320 sites (92%) of 100 patients (82%), more commonly in men (P < 0.03), in older patients (P < 0.0001), in patients with hypertension (P < 0.003) or hyperlipidemia (P < 0.04), and in smokers (P < 0.008). Increased vascular-wall (18)F-FDG uptake (PET+) was observed at 52 sites (15%) of 38 patients (31%), more commonly in men (P < 0.02), in older patients (P < 0.0001), and in patients with hypertension (P < 0.02), and was borderline in patients with cardiovascular disease (P = 0.057). PET+ and CT+ findings correlated in 12 patients, a PET+/CT- pattern was found in 18 patients, and 8 patients had increased vascular-wall (18)F-FDG uptake in sites with and without calcifications (PET+/CT+, CT-). Twenty-two patients (18%) had a PET-/CT- pattern. CONCLUSION: Hybrid PET/CT can be used to identify and to correctly localize vascular-wall (18)F-FDG activity. Increased vascular-wall (18)F-FDG activity was found in 15% of sites and CT calcifications were noted in 92% of sites, with congruent findings in 7%. The clinical significance of the relationship between vascular-wall (18)F-FDG uptake and CT calcifications needs to be assessed by further prospective studies with long-term follow up.     

Prospective assessment of 18F-FDG PET/CT in detection of recurrent ovarian cancer

Objective

To assess the use of positron emission tomography (PET)/computed tomography (CT) in patients with suspected ovarian cancer recurrence and describe the distribution of metastasis.

Patients and methods

This study included (39) patients suspected to have recurrent ovarian malignancy. This suspicion was either clinically, radiologically or due to raised CA-125 levels. All patients underwent 18F-FDG PET/CT, surgery was performed within 8 weeks of imaging studies. Surgical and/or histopathological examinations were available in 31 patients, and clinical, radiological and CA 125 serum level follow up in 8 patients.

Results

The overall lesion-based sensitivity, specificity, and accuracy of PET/CT for revealing recurrent ovarian carcinoma were 90%, 98% and 97%, respectively. The patient – based sensitivity, specificity, and accuracy of PET/CT were 97%, 75% and 95%, respectively.

Conclusion

18F-FDG PET/CT is a useful tool for evaluating the recurrence of ovarian cancer after first-line therapy in patients with a high risk of relapse, equivocal radiologic findings, increased or normal levels of serum CA-125. It can more accurately diagnose and localize recurrence, hence decreasing the rate of second look surgery and changing treatment plan.     

Assessment of ovarian teratoma and lymphadenopathy by 18F-FDG PET/CT

Two women presented with abdominal complaints; after clinical investigation and ultrasonography, both were suspected of having (ovarian) teratoma. The CT scan showed enlarged para-aortic lymph nodes, which increased the suspicion of a malignant process. Total-body 18F-FDG PET/CT studies helped to differentiate benign from malignant ovarian teratoma, as well as abdominal lymphadenopathy, subsequently confirmed by histopathology. When there is suspicion of a malignant teratoma, 18F-FDG PET/CT may help in accurate diagnosis and staging; as for malignant disease (either malignant transformation of mature cystic teratoma or malignant immature teratoma), a more aggressive, multimodality approach may be indicated.     

Malignant involvement of the spine: assessment by 18F-FDG PET/CT.

The purpose of the study was to assess the role of (18)F-FDG PET/CT in the assessment of secondary malignant involvement of the spinal column. METHODS: In 51 patients, 242 lesions at the spinal region detected on (18)F-FDG PET/CT were interpreted separately on PET, CT, and fused PET/CT images, including differentiation between benign and malignant lesions and the level in the vertebral column. CT evaluation also included the type of bony lesion (osteolytic, osteoblastic, or mixed) and accompanying soft-tissue abnormalities; for example, epidural masses and tumor involvement of the neural foramina. RESULTS: Of the 242 lesions detected on PET/CT, PET alone identified 220 lesions and CT alone identified 159; 217 (90%) were malignant and 25 benign. (18)F-FDG PET alone detected significantly more malignant lesions than did CT alone (96% vs. 68%, respectively, P < 0.001). The specificity was 56% for both PET alone and CT alone. PET alone was incorrect in determining the level of abnormality within the vertebral column in 33 (15%) lesions and in determining the part of the vertebra involved in 40 (18%) lesions. In 17 (33%) patients, either epidural extension of tumor (n = 7 lesions), neural foramen involvement of tumor (n = 7 lesions), or a combination of both (n = 11 lesions) was detected. On a patient-based analysis, the sensitivity of PET and of PET/CT for the detection of spinal metastasis was 98% and 74%, respectively (P < 0.01). CONCLUSION: (18)F-FDG PET/CT has better specificity for detection of malignant involvement of the spine than does (18)F-FDG PET. It allows for precise localization of lesions and identifies accompanying soft-tissue involvement, which is of potential neurologic significance.     

Increased 18F-FDG uptake in degenerative disease of the spine: Characterization with 18F-FDG PET/CT.

We determined the prevalence of abnormal spinal 18F-FDG uptake and assessed the relationship between the severity of findings on 18F-FDG PET and the severity of degenerative spinal disease (DSD) on CT. METHODS: PET/CT scans of 150 patients >18 y old, referred for whole-body 18F-FDG PET/CT for evaluation of known or suspected malignancy from June to July 2002, were analyzed retrospectively for the presence of increased 18F-FDG uptake in the spine and for anatomic correlates. Initially, PET images were examined and foci of 18F-FDG uptake in the spine were graded on a 0-4 scale based on intensity of 18F-FDG uptake (0 = definitely normal, 1 = probably normal, 2 = equivocal, 3 = probably abnormal, 4 = definitely abnormal). From PET alone, an impression as to whether lesions were most likely metastases or degenerative, as well the level of the spine involved, was also recorded. CT images of all 150 patients were reviewed independently by a musculoskeletal radiologist, who was unaware of patient identification, history, and findings of other imaging modalities, with the location recorded and severity graded on a 4-point-scale (0 = normal, 1 = mild, 2 = moderate, 3 = severe for both degenerative disk and facet disease). The relationship between PET and CT findings was then determined. RESULTS: Of the 150 patients, 63 (42.0%) had no abnormal findings in the spine on PET (grade 0), 27 (18.0%) had grade 1, 25 (16.7%) had grade 2, 17 (11.3%) had grade 3, and 16 patients (10.7%) had grade 4 18F-FDG uptake for DSD. Two additional patients had apparent spinal metastases with no degenerative changes. Five patients had metastases and DSD (included above). Of the patients who had abnormal spinal findings graded as probable or definite for DSD on CT (grades 3-4), 11 had abnormal findings in the cervical spine, 16 in the thoracic spine, and 23 patients in the lumbosacral spine. Seven patients (4.7%) had PET findings suggestive of spinal metastases. For patients with a maximum regional DSD score of 3, the mean 18F-FDG uptake for that spinal level was 1.4 +/- 1.5, whereas for patients with a maximum regional DSD score of 0, the mean PET grade was significantly lower at 0.4 +/- 0.9 (P = 0.0001). CONCLUSION: Incidental findings on PET suggestive of DSD are common (22% of patients), most common in the lumbosacral spine, and can be recognized on CT. The severity of PET findings correlates with the severity of degenerative disk and facet disease as graded by CT, likely due to the fact that the inflammatory process that accompanies DSD is evident on PET. Increased 18F-FDG uptake in DSD should not be confused with metastatic disease.     

Normal uptake of <Superscript>18</Superscript>F-FDG in the testis: an assessment by PET/CT

Objective The aim of this study was to assess the physiological uptake of ¹⁸F-fluoro-2-deoxyglucose (FDG) by an apparently normal testis with combined positron emission tomography–computed tomography (PET/CT) and its correlation with age, blood glucose level, and testicular volume. Methods The testicular uptake of ¹⁸F-FDG, expressed as the standardized uptake value (SUV), was measured on PET/CT images in 203 men. The correlation between SUV and age, blood glucose level, and testicular volume was assessed. Results The SUV in the total of 406 testes was 2.44 ± 0.45 (range 1.23–3.85). The SUV was 2.81 ± 0.43 (2.28–3.85) for 30–39 years (n = 12), 2.63 ± 0.45 (1.77–3.75) for 40–49 years (n = 64), 2.46 ± 0.35 (1.44–3.15) for 50–59 years (n = 82), 2.51 ± 0.41 (1.50–3.46) for 60–69 years (n = 86), 2.43 ± 0.47 (1.42–3.29) for 70–79 years (n = 86), and 2.18 ± 0.45 (1.23–3.03) for 80–89 years (n = 76). When we calculated the mean SUV of bilateral testes in each patient, there were significant statistical differences between those in the age group of 30–39 years and 80–89 years, 40–49 years and 80–89 years, and 50–60 years and 80–89 years, when using an unpaired test with Bonferroni correction. The laterality index (|L − R|/(L + R) × 2) in 203 men was 0.066 ± 0.067 (0–0.522). There was a mild correlation between the mean SUV and age (r = −0.284, P < 0.001) as well as between the mean SUV and mean volume (r = +0.368, P < 0.001). There was no correlation between the mean SUV and glucose blood level (r = −0.065, P = 0.358). Conclusions Some uptake of FDG is observed in the normal testis and declines slightly with age. Physiological FDG uptake in the testis should not be confused with pathological accumulation.     

18F-FDG uptake in the normal appendix in adults: PET/CT evaluation

Annals of Nuclear Medicine - This study aimed to determine the level of 18F fluorodeoxyglucose (18F-FDG) activity in the normal adult appendix using positron emission tomography/computed tomography...     

18F-FDG PET/CT伪影和不常见生理性摄取分析

目的 探讨^18F-脱氧葡萄糖（FDG）PET/CT显像各种伪影的影像学表现及其产生的原理.方法 回顾性分析^18F-FDG PET/CT检查患者的图像,根据伪影产生的原因进行分类,同时对临床不常见的生理性摄取进行分析.结果 伪影分为自身因素和设备技术因素伪影,自身因素所致伪影中以呼吸运动伪影和高密度物质伪影最为常见;设备因素伪影中以截断伪影、注射点外漏和放射性污染最为常见.不常见的生理性摄取包括：子宫内膜摄取、乳腺摄取和脂肪摄取.结论 PET显像伪影影像学表现可分为“热区”或“冷区”.不常见的生理性摄取主要表现为“热区”.伪影产生原因中以CT应用于PET显像后物理学因素多见.不常见的生理性摄取与检查技术有关.     

Normal and abnormal patterns of 18F-fluorodeoxyglucose PET/CT in lymphoma

In spite of the high performance of 18F-fluorodeoxyglucose (FDG) PET for the evaluation of lymphoma, inherent limitations of this modality underscore the additional value of PET/CT as an important tool in the assessment of this disease. Accumulating data on the use of PET/CT in lymphoma indicate the contribution of hybrid imaging to improved interpretation accuracy of PET using FDG and CT. Knowledge of the normal and abnormal patterns of FDG-PET/CT imaging and their variability in patients with lymphoma is important to provide a comprehensive clinically significant interpretation that has an impact on patient management and potentially on outcome.     

Physiological 18F-FDG uptake in the normal adult anal canal: evaluation by PET/CT

Annals of Nuclear Medicine - Despite their benefit for detecting primary tumors, data for normal 18F-fluoro-2-deoxy-d-glucose (FDG) uptake in the anal canal are insufficient. Here we used positron...     

Correlations between 18F-FDG uptake by bone marrow and hematological parameters: measurements by PET/CT

The aim of this study was to investigate the correlations between ¹⁸F-FDG uptake by bone marrow and various hematological parameters.

Forty-eight patients who underwent FDG-PET/CT studies and also received hematological examinations within 5 days before or after the PET study were included in this study. All patients had not received chemotherapy. FDG uptake by bone marrow was measured as a standardized uptake value (SUV) on three-dimensional PET/CT fusion images, and the uptake ratio (UR) of the SUV of bone marrow to the SUV of longitudinal dorsal muscle was calculated. The correlations between the SUV and the UR of bone marrow and various hematological parameters were evaluated.

Bone marrow FDG uptake was strongly correlated with the white blood cell counts but was not significantly correlated with the red blood cell and platelet counts. The neutrophil count was significantly correlated with bone marrow FDG uptake but the lymphocyte count was not.

FDG uptake by bone marrow was specifically correlated with the neutrophil count, suggesting that the FDG uptake by bone marrow reflects marrow metabolism that is mainly regulated by granulocyte progenitors and stimulated by endogenous hematopoietic growth factors. They may also be helpful in interpreting PET images, especially for diagnosing bone marrow involvement by malignancy.     

Influence of reconstruction iterations on 18F-FDG PET/CT standardized uptake values.

The goal of this study was to evaluate the effect on the average standardized uptake value (avgSUV) and maximum standardized uptake value (maxSUV) of changing the number of iterations in the reconstruction process on studies acquired with PET/CT. METHODS: Data from 50 human tumors were acquired on a PET/CT scanner, using the CT portion for attenuation correction. Reconstruction was performed using the 2-dimensional reconstruction method of ordered-subsets expectation maximization (OSEM) with 28 subsets and with 1, 2, 3, 4, 5, 10, 20, and 40 iterations. The standardized uptake value (SUV) of the studies was analyzed by positioning a region of interest tightly around the tumor and reproducing the same area on all same-study iterations for SUV measurements. RESULTS: The differences in mean avgSUV and mean maxSUV were statistically different across different iteration groups. SUV data demonstrated that the avgSUV measurements have the most significant differences between 1 versus 2 iterations and 2 versus 3 iterations. The P values for these comparisons were less then 0.001. For maxSUV, all differences had P values less than 0.001. There also was a systematic increase in the SUVs as the number of iterations increased. The avgSUV increased at early iterations (less than 5), with just 50%-60% increasing after 5 iterations. However, maxSUV increased systematically at early iterations, and this trend continued as the number of iterations increased. CONCLUSION: The OSEM algorithm converges sooner for avgSUV than for maxSUV. The likely reason is that avgSUV depends on low-frequency features that are recovered with fewer iterations. The differences in maxSUV were likely due to noise, which increased with the number of iterative updates, and to increased resolution and recovery of high-frequency features (i.e., tumor heterogeneity) with a larger number of iterations. Factors that determine the quantitative accuracy of iterative reconstruction may have played an additional role. Given the continued change in maxSUV with iterations, great care must be taken in selecting the number of iterative updates when using it to assess tumors and their response to chemotherapy and radiation therapy. Because 2-5 iterations with 8-28 subsets are being used in clinical settings, these data are pertinent when comparing the SUVs of a tumor before and after therapy.     

~(18)F-FDGPET/CT棕色脂肪摄取的影像学分析

目的:分析18F-FDG PET/CT检查中棕色脂肪组织(BAT)摄取的规律和特点,以避免不必要的误诊。方法:回顾性分析行PET/CT全身检查的2350例受检者的图像。结果:34例(1.44%)有不同程度BAT摄取,其中恶性肿瘤患者9例(甲状腺癌术后4例)。BAT显影主要在寒冷季节出现,女性比例(2.57%)高于男性(0.76%);特征性表现为对称性分布于肩颈部、锁骨上区、脊柱两旁、纵隔、肾上腺及肾周区的高摄取灶,SUVmax为7.18±4.27。BAT显影部位的数目与摄取的SUVmax呈正相关(r=0.78,P<0.05);5例检查者进行了延迟扫描,延迟后BAT分布、形态无明显变化,SUVmax显著升高(P<0.05)。4例甲状腺癌术后复查病例的BAT摄取不同程度影响了对区域淋巴结的观察。结论:BAT摄取的分布及影像表现具有一定的特征性,显影部位越多,SUVmax越大,延迟扫描后SUVmax显著升高,容易干扰对显影区域病灶的观察。     

Incidental pituitary uptake on whole-body 18F-FDG PET/CT: a multicentre study

Purpose

The purpose of this study was to determine the incidence of incidental pituitary uptake on whole-body ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and to investigate its clinical significance.

Methods

The files of 40,967 patients who underwent whole-body FDG PET/CT were retrospectively reviewed. Quantification of pituitary metabolic activity was obtained by using the maximum standardized uptake value (SUV_max). Hormone assays and pituitary MRIs were performed to assess pituitary lesions.

Results

Focally increased pituitary FDG uptake on PET/CT was found in 30 of 40,967 patients, accounting for an incidence of 0.073%. The mean SUV_max of 30 patients was 8.9?±?6.6 (range: 3.2–32.6). Histological diagnosis was obtained in three patients and included two growth hormone-secreting adenomas and one non-functioning adenoma. Hormone assays were performed on serum samples from 11 patients, 2 of whom were shown to have hypersecretion of pituitary hormone. MRI was performed on 19 patients. Abnormal MRI findings suggesting a pituitary mass were found in 18 of 19 cases (94.7%). The mean SUV_max calculated without correction for partial volume effect for macroadenomas was significantly higher than the SUV_max for microadenomas (11.5?±?8.4 vs 4.8?±?1.3; p?<?0.05). There were no cases diagnosed with metastasis to the pituitary gland during clinical follow-up.

Conclusion

Incidental pituitary FDG uptake was a very rare finding. Cases with incidental pituitary FDG uptake were diagnosed primarily with clinically non-functioning adenomas, and there were also a few functioning adenomas. Further evaluations, including hormone assays and pituitary MRI, are warranted when pituitary uptake is found on FDG PET/CT.