Diagnosis of Recurrent Uterine Cervical Cancer: Computed Tomography versus Positron Emission Tomography

Objective

To determine the accuracy of CT and positron emission tomography (PET) in the diagnosis of recurrent uterine cervical cancer.

Materials and Methods

Imaging findings of CT and PET in 36 patients (mean age, 53 years) in whom recurrent uterine cervical cancer was suspected were analyzed retrospectively. Between October 1997 and May 1998, they had undergone surgery and/or radiation therapy. Tumor recurrence was confirmed by pathologic examination or follow-up studies.

Results

In detecting recurrent uterine cervical cancer, the sensitivity, specificity, and accuracy of CT were 77.8%, 83.3%, and 80.5%, respectively, while for PET, the corresponding figures were 100%, 94.4%, and 97.2%. The Chi-square test revealed no significant difference in specificity (p = .2888), but significant differences in sensitivity (p = .0339) and accuracy (p = .0244).

Conclusion

PET proved to be a reliable screening method for detecting recurrent uterine cervical cancer, but to determine the anatomical localization of recurrent tumors, and thus decide an adequate treatment plan, CT was eventually needed.     

Obesity and Brain Positron Emission Tomography

Obesity, an increasingly common problem in modern societies, results from energy intake chronically exceeding energy expenditure. This imbalance of energy can be triggered by the internal state of the caloric equation (homeostasis) and non-homeostatic factors, such as social, cultural, psychological, environmental factors or food itself. Nowadays, positron emission tomography (PET) radiopharmaceuticals have been examined to understand the cerebral control of food intake in humans. Using ¹⁵O–H₂ PET, changes in regional cerebral blood flow (rCBF) coupled to neuronal activity were reported in states of fasting, satiation after feeding, and sensory stimulation. In addition, rCBF in obese subjects showed a greater increase in insula, the primary gustatory cortex. ¹⁸F–fluorodeoxyglucose PET showed higher metabolic activity in postcentral gyrus of the parietal cortex and lower in prefrontal cortex and anterior cingulate cortex in obese subjects. In addition, dopamine receptor (DR) PET demonstrated lower DR availability in obese subjects, which might lead to overeating to compensate. Brain PET has been utilized to reveal the connectivity between obesity and brain. This could improve understanding of obesity and help develop a new treatment for obesity.     

Tumor Burden Assessment with Positron Emission Tomography with

Objective: In patients with advanced cancer, total tumor burden affects the likelihood of tumor response and has important implications for prognosis. The aim of this study was to select the optimum 2-[F-18]fluoro-2-deoxy-D-glucose-positron emission tomography (FDG PET) tumor uptake parameter to accurately measure tumor burden in advanced metastatic renal cell cancer, in comparison with volumes measured with computed tomography (CT), as a reference test.Materials and Methods: Six patients with metastatic renal cell carcinoma measurable on CT were studied. CT and FDG PET scans were carried out on all patients within 4 weeks prior to their entry into a phase I-II radioimmunotherapy trial. CT-based evaluation of disease extent (tumor volume) and 4 PET-based measurements (standardized uptake value[SUVmax], SUVav, volume, and total lesion glycolysis [TLG]) were performed independently by a radiologist (VN) and a nuclear medicine physician (TA). The degree of correlation between conventional (CT) extent of disease and parameters describing tumor concentration of FDG was then determined.Results: Fifty-seven CT-measurable metastatic lesions in lung, abdomen, and scalp were evaluated in 6 patients. There was a high correlation between CT and FDG PET volume estimates for lesions greater than 5 cm(3) in size. However, a PET-derived parameter that embodies both FDG uptake and lesion size, the TLG, correlated better with CT-derived tumor volume than did FDG PET volume alone.Conclusion: Using CT volume as a gold standard, the optimal PET-based estimate of total tumor burden in patients with metastatic renal cancer is the sum over all lesions of the total lesion glycolysis.     

Status of Positron Emission Tomography in Japan

In 1997, 11,040 PET examinations were estimated to have been performed on humans in 24 PET facilities in Japan. PET procedures were used for the studies of the brain (45.0%), tumors (31.3%), and heart (22.9%). (18)F labeled tracers are most frequently utilized followed by (15)O, (13)N, and (11)C labeled tracers in that order. Instrumentations used for PET including cyclotrons and PET scanners are listed. Status of clinical PET and future strategy in our national health insurance system is described. PET examinations performed for clinical oncology and research in our institute are discussed.     

Prognostic value of SUVmax measured by Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography with Computed Tomography in Patients with Pancreatic Cancer

Purpose

Recent studies have been conducted on the relationship between fluorodeoxyglucose (FDG) uptake in F-18 FDG PET/CT and prognosis in patients with pancreatic cancer, but these studies have been carried out in small numbers of patients. The aim of this retrospective study was to determine in a large number of patients whether glucose metabolism as assessed by F-18 FDG PET/CT provides prognostic information independent of established prognostic factors in patients with pancreatic cancer.

Methods

We reviewed retrospectively the medical records of 165 patients (men 105, women 60, mean age 67 ± 10 years) with a diagnosis of pancreatic cancer that had undergone F-18 FDG PET/CT as part of a pretreatment workup from January 2004 to December 2009. Subsequently, all patients underwent surgery, cyberknife, radiotherapy, and/or chemotherapy. For the analysis, patients were classified by age, demographic data, maximum standardized uptake value (SUVmax), size, location, serum level of CA19-9, type of treatment, and AJCC stage. The relationship between FDG uptake and survival was analyzed using the Kaplan-Meier with log-Rank test and Cox’s proportional-hazard regression methods.

Results

Median survival for all 165 study subjects was 290 days and median SUV by PET/CT was 5.8 (range: 0–25.1). Patients were allocated to high (> 4.1) and low (≤4.1) SUV groups, and median survivals of these patients were 229 days and 610 days, respectively, which were significantly different (p < 0.0001). Furthermore, SUVmax was found to be significantly related to survival in each stage, i.e., there were 1267 days in stage I, 440 days in stage II, 299 days in stage III, and 143 days in stage IV (p < 0.0001). The median survival was also found to be significantly related to tumor size (p = 0.001), site (p = 0.0298), serum level of CA19-9 (p = 0.0017), distant metastasis (p < 0.0001), and type of treatment (p < 0.0001). Multivariate analysis study revealed that the patients with a low SUV (p = 0.0298), a lower serum level of CA19-9 (p = 0.0071), a lower stage (p = 0.0017), and no distant metastasis (p < 0.0001) had longer survivals. In addition, SUVmax values were found to have a similar hazard ratio of distant metastasis; it was well known predictor. Furthermore, SUVmax values showed a higher hazard ratio than that of other clinicopathologic predictors.

Conclusion

The present study shows that SUVmax on F-18 FDG PET/CT can provide a prognostic information in patients with pancreatic cancer.     

Prognostic Value of SUVmax Measured by Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography with Computed Tomography in Patients with Gallbladder Cancer

Objective

The aim of this study is to investigate the prognostic value of F-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET)/computed tomography (CT) in gallbladder cancer patients.

Methods

From June 2004 to June 2010, a total of 50 patients with gallbladder cancer who underwent diagnostic staging with F-18 FDG PET/CT following curative or palliative treatments were retrospectively evaluated. For the analysis, all patients were classified by age, sex, maximum standardized uptake value (SUVmax), lymph node (LN) or distant metastasis, serum level of CA19-9 and CEA, type of treatment and American Joint Committee on Cancer (AJCC) stage.

Results

The median survival for the 50 patients was 245 days and the median SUVmax in PET/CT was 8.3 (range, 0-19.7). Patients with SUVmax < 6 survived significantly longer than patients with SUVmax ≥ 6 (median 405 days vs 203 days, p = 0.0400). On Kaplan-Meier analysis, SUVmax (p = 0.0400), stage (p = 0.0001), CA19-9 (p = 0.013), CEA (p = 0.006), LN metastasis (p = 0.0001), distant metastasis (p = 0.0020), type of treatment (p = 0.0001) were significantly associated with overall survival. Multivariate analysis study revealed that the patients with lower SUVmax measured from initial staging PET/CT (p = 0.0380), no LN metastasis (p = 0.0260), a lower stage (p = 0.026) and curative treatment (p = 0.0005) had longer survivals.

Conclusions

The present study shows that SUVmax on F-18 FDG PET/CT can provide prognostic information in patients with gallbladder cancer.     

Positron Emission Tomography in Grading Soft Tissue Sarcomas

Soft tissue sarcomas present with varied radiological appearances. Positron imaging with [F-18] fluorodeoxyglucose (FDG PET) has recently made promising contributions to management of patients by providing a noninvasive means for evaluating tumor metabolism and providing important biological information about soft tissue malignant tumors. PET imaging not only gives quantitative data on metabolic rates of tumors but can also readily provide semiquantitative data of uptake of tumors by measuring uptake ratios. These values have been helpful for noninvasively grading tumors. This value is called the tumor standard uptake value (SUV). The tumor grades (low, intermediate, high) mean SUV values show a high level of significance in discrimination among tumor grade groups.