The influence of I-131 therapy on FDG uptake in differentiated thyroid cancer

OBJECTIVE: 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) [or PET/computed tomography (CT)] is more likely to show false-negative results when it is performed shortly after chemotherapy and/or radiotherapy because of "metabolic stunning". The present study aimed to evaluate the influence of I-131 therapy on FDG uptake and the detection of recurrence or metastasis of differentiated thyroid cancer (DTC). METHODS: We retrospectively enrolled 16 consecutive FDG-PET/CT studies which had been performed in patients with DTC with elevated thyroglobulin (TG) but negative I-131 whole-body scan. All studies were performed under L: -thyroxine suppression. The patients were divided into groups A and B for PET/CT performed within 4 months of I-131 therapy or no such therapy, respectively. Each lesion identified on PET/CT was characterized using a 5-point scale by visual analysis: 0 = definitely benign, 1 = probably benign, 2 = equivocal, 3 = probably malignant, and 4 = definitely malignant. The maximum standardized uptake value (SUV max) in each lesion was also measured for semiquantitative analysis. We compared the visual grading and SUV max of the lesion of highest FDG uptake between groups A and B. RESULTS: For visual analysis, group B had significantly more patients with an uptake score of 3 or 4 than group A (80% vs. 17%, P = 0.01). In addition, there were significantly more equivocal results from group A than from group B (67% vs. 10%, P = 0.02). If the patients with the highest uptake scores of 2, 3, and 4 were considered to be positive for local recurrence or metastasis, there would be no significant difference between the positive rates of groups A and B (83% vs. 90%, P = 0.7). However, the mean SUV max of positive results was significantly lower for group A than for group B (3.1 +/- 0.9 and 6.6 +/- 3.5, respectively, P = 0.02). CONCLUSIONS: The preliminary results suggested that FDG uptake in DTC may be negatively influenced by I-131 therapy within 4 months, resulting in lower FDG uptake and more equivocal results. Further studies are necessary to determine whether it is secondary to "metabolic stunning" caused by I-131 therapy.     

Initial experience with FDG-PET/CT in the evaluation of breast cancer

Purpose We retrospectively reviewed FDG-PET/CT images in patients with breast cancer to determine whether PET/CT improved the level of diagnostic confidence as compared with PET and to compare PET/CT and CT findings at the location of suspected malignancies.Methods The study included 75 patients with known breast cancer. The initial PET/CT study for each patient was retrospectively reviewed to determine whether improved diagnostic confidence (IDC) regarding lesion localization and characterization was observed with PET/CT as compared with PET alone. PET/CT and CT findings were compared regarding lesion characterization and staging in 69 of the 75 patients, and in the case of discordant findings, comparison with histological or informative follow-up results was also performed.Results Fifty of the 75 patients exhibited increased FDG uptake in a total of 95 regions. In the comparison of PET/CT and PET, PET/CT resulted in IDC in 30 (60%) of these 50 patients and in 52 (55%) of the 95 regions. In the comparison between PET/CT and CT in 69 patients, PET/CT demonstrated a significantly better accuracy than CT (P<0.05). PET/CT showed definitely positive findings in 60 regions with malignancies, among which CT exhibited positive findings in 43 (72%). PET/CT and CT accurately staged 59 (86%) and 53 (77%) of the 69 patients, respectively.Conclusions PET/CT added incremental diagnostic confidence to PET in more than 50% of patients and regions with increased FDG uptake. PET/CT accurately detected more regions with malignancies than did CT. This initial evaluation suggests that PET/CT is preferable to PET or CT in the diagnosis of breast cancer.     

Performance of integrated FDG-PET/contrast-enhanced CT in the diagnosis of recurrent uterine cancer: comparison with PET and enhanced CT

Purpose  To evaluate the accuracy of integrated positron emission tomography and computed tomography (PET/CT) with iodinated contrast agent and ¹⁸F-fluorodeoxyglucose (FDG) in the diagnosis of suspected uterine cancer recurrence and to assess the impact of PET/CT findings on clinical management, compared with PET alone and enhanced CT alone. Methods  Of 103 women who had undergone treatment for histopathologically proven uterine cervical or endometrial cancer, 90 underwent FDG-PET/contrast-enhanced CT examination for suspected recurrence. PET-alone, CT-alone, and fused PET/CT images were interpreted by two radiologists by consensus for each investigation. Lesion status was determined on the basis of histopathology, radiological imaging and clinical follow-up for longer than 6 months. Differences among the three modalities were tested using the Cochran Q test, followed by multiple comparisons using the McNemar test with Bonferroni adjustment. Results  Patient-based analysis showed that the sensitivity, specificity, and accuracy of PET alone were 79.5% (35/44), 73.9% (34/46), and 76.7% (69/90), respectively, whereas those of CT alone were 68.2% (30/44), 87.0% (40/46), and 77.8% (70/90), respectively, and those of PET/CT were 90.9% (40/44), 93.5% (43/46), and 92.2% (83/90), respectively. PET/CT findings resulted in a change of management in 38 of the 90 patients (42%) with an additional effect on patient management in 13 patients (14%) diagnosed by CT alone and 14 patients (16%) diagnosed by PET alone. Conclusion  FDG-PET/contrast-enhanced CT is a more accurate modality for assessing recurrence of uterine cancer, and led to more appropriate subsequent clinical management than that resulting from PET alone or enhanced CT alone.     

FDG-PET/CT in re-staging of patients with lymphoma

The aim of this study was to evaluate the clinical significance of combined fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT) in patients with lymphoma, and to compare the FDG-PET/CT staging results with those of FDG-PET and CT alone. Twenty-seven patients were studied. Each patient had clinical follow-up for >12 months and entered complete follow-up evaluation. Patient-based evaluation showed a sensitivity of 78% for CT alone, 86% for FDG-PET alone, 93% for CT and FDG-PET read side by side, and 93% for combined FDG-PET/CT imaging. Region-based evaluation showed a sensitivity for regional lymph node involvement of 61%, 78%, 91% and 96% respectively. FDG-PET/CT imaging is superior to CT alone (P=0.02) and has additional benefit over FDG-PET alone due to exact anatomical localisation. We conclude that FDG-PET/CT imaging is accurate in re-staging lymphoma and offers advantages over separate FDG-PET and CT imaging.     

Imaging surveillance of differentiated thyroid cancer

Intensive imaging surveillance has resulted in the ability to detect small-volume, often clinically occult, residual or recurrent disease. For most patients with differentiated thyroid cancer (DTC), such findings are unlikely to have an impact on disease-specific survival but our ability to predict which patients are at greatest risk and should receive the most aggressive therapies is surpassed by our ability to detect recurrence. Thus, the optimal treatment and surveillance regimens will surely continue to evolve as our ability to predict tumor behavior and aggressiveness improves. This article explains the rationale underlying current surveillance strategies and the utility and implications of imaging findings that are critical for the appropriate care of patients with DTC.     

The diagnostic usefulness of FDG-PET/CT in detecting tumor recurrence not evident in whole body I scan in differentiated thyroid carcinoma

Objective

Patients with differentiated thyroid carcinoma (DTC) have generally an encouraging prognosis, however, some patients develop an increasing level of serum thyroglobulin (Tg) without detection of a recurrent tumor using conventional imaging tools such as the iodine-131 whole-body scanning (I¹³¹ scan). The objective of our study was to evaluate the clinical significance of [F¹⁸]-FDG-PET/CT in detection of tumor recurrence or metastases, in comparison to conventional imaging such as the I¹³¹ scan.

Patients and methods

Between January 2013 and June 2013, [18F]-FDG-PET/CT examination was done for 12 DTC patients with elevated thyroglobulin levels and who did not show any pathological lesions when conventional imaging modalities were used. All involved patients had undergone total thyroidectomy, and who had been followed-up by whole body iodine scan [F¹⁸]-FDG PET/CT data were evaluated for detecting recurrent DTC lesions in study patients and compared with those of other radiological and/or cytological investigations.

Results

Five of 12 patients (41.6 %) showed pathological [F18]-FDG uptake in the absence of abnormal uptake in whole body iodine scan.

Conclusion

[F18]-FDG-PET/CT affords a valuable diagnostic method in detection of recurrence or metastasis in patients with DTC who are tumor-free on conventional imaging studies with high Tg levels.     

The value of FDG-PET/CT in assessing single pulmonary nodules in patients at high risk of lung cancer

Purpose  To evaluate whether PET/low-dose CT (ldCT) using ¹⁸F-fluorodeoxyglucose (FDG) improves characterization of indeterminate single pulmonary nodules (SPNs) in patients at high risk of lung cancer. Methods  Retrospective analysis of 307 patients who underwent FDG-PET/CT for indeterminate SPNs identified 93 (70 men, age range 46–90 years) at high risk of lung cancer (age >40 years, minimum 10 pack-year smokers). SPNs were evaluated for the presence and intensity of FDG avidity and ldCT patterns. The performance of visual and semiquantitative FDG-PET/ldCT algorithms for characterization of SPNs was compared to that of ldCT. Incongruent FDG-PET and ldCT patterns were analyzed for significance in further patient management. Results  Malignancy was diagnosed in 38% patients. FDG avidity defined 33 SPNs as true-positive (TP) and 2 as false-negative (FN) (malignant), and 41 as true-negative (TN) and 17 as false-positive (FP) (benign). For SUVmax of 2.2 (by ROC analysis) there were 27 TP, 8 FN, 48 TN and 10 FP SPNs. LdCT defined 34 TP, 1 FN, 28 TN and 30 FP lesions. Of the FP lesions on ldCT, 60% were FDG-negative. Visual PET/ldCT analysis had a sensitivity of 94%, a specificity of 70%, an accuracy of 80%, a positive predictive value (PPV) of 66%, and a negative predictive value (NPV) of 95% as compared to 77%, 83%, 81%, 73%, 86% for semiquantitative PET/ldCT and 97%, 48%, 66%, 53%, 96% for ldCT, respectively. Both PET/ldCT algorithms had statistically significantly higher specificity and accuracy than ldCT. Semiquantitative analysis showed significantly higher PPV and lower sensitivity and NPV than found with ldCT. Conclusion  A single screening procedure encompassing FDG-PET and ldCT may improve screening for lung cancer in high-risk patients. The significantly improved specificity may potentially reduce FP ldCT results and further unnecessary invasive procedures.     

Accuracy of integrated FDG-PET/contrast-enhanced CT in detecting pelvic and paraaortic lymph node metastasis in patients with uterine cancer

The purpose is to evaluate the accuracy of integrated ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography ((CT) with intravenous contrast medium in detecting pelvic and paraaortic lymph node metastasis in patients with uterine cancer, with surgical and histopathological findings used as the reference standard. Forty-five patients with endometrial or uterine cervical cancer underwent radical hysterectomy, including pelvic lymphadenectomy with or without paraaortic lymphadenectomy, after PET/CT. PET/CT findings were interpreted by two experienced radiologists in consensus. The criterion for malignancy on PET/CT images was increased tracer uptake by the lymph node, independent of node size. The overall node-based sensitivity, specificity, PPV, NPV and accuracy of PET/CT for detecting nodal metastases were 51.1% (23/45), 99.8% (1,927/1,931), 85.2% (23/27), 98.9% (1,927/1,949) and 98.7% (1,950/1,976), respectively. The sensitivity for detecting metastatic lesions 4 mm or less in short-axis diameter was 12.5% (2/16), that for between 5 and 9 mm was 66.7% (16/24), and that for 10 mm or larger was 100.0% (5/5). The overall patient-based sensitivity, specificity, positive predictive value ((PPV), negative predictive value (NPV), and accuracy were 50% (6/12), 90.9% (30/33), 66.7% (6/9), 83.3% (30/36) and 80.0% (36/45), respectively. Integrated FDG-PET/contrast-enhanced CT is superior to conventional imaging, but only moderately sensitive in predicting lymph node metastasis preoperatively in patients with uterine cancer.     

分化型甲状腺癌~(18)F-FDG PET显像的临床应用

低分化型甲状腺癌细胞摄取碘能力的下降或丧失导致 1 31 　 I WBS(全身显像 )假阴性 (约 2 0 % ) ,高水平的血清 Tg(甲状腺球蛋白 )只能说明有分化型甲状腺癌 (DTC)的复发或转移 ,不能确定 DTC复发或转移的具体位置 ,而低分化型甲状腺癌正是 DTC病人死亡的主要类型。本文主要探讨 1 8F- FDG(1 8F-氟代脱氧葡萄糖 ) PET显像在1 31　 I的 WBS阴性而血清 Tg水平增高的 DTC病人中鉴别复发和转移的应用以及评价 DTC病人预后的价值 ,当嗜1 8F- FDG肿瘤显示的体积大于 12 5 m L 或 FDG标准摄取值大于 10 g/ m L 时 ,病人的预后不良。     

Usefulness of FDG-PET/CT in the detection of pancreatic metastases from lung cancer

Objective  The objective of this study was to assess the ability to detect pancreatic metastasis of lung cancer and to clarify the degree of fluorodeoxyglucose (FDG) accumulation and computed tomography (CT) characteristics of pancreatic metastasis from lung cancer. Methods  A total of 573 patients (415 men and 158 women) with lung cancer were retrospectively evaluated. All patients underwent FDG-positron emission tomography (PET)/CT with contrast-enhanced CT for first=stage (313 patients; initial study group) or follow-up study (260 patients; follow-up study group). A lesion was regarded as positive for metastasis on the basis of visual judgment of the degree of increased metabolism by two experienced and independent interpreters, supported by semiquantitative evaluation on the basis of calculation of the maximum standardized uptake value (SUV_max). Results  Abnormal accumulations in the pancreas were detected in 5 of 313 patients (1.60%) in the initial study group, and 6 of 260 patients (2.31%) in the follow-up study group. Seven of these patients had adenocarcinoma, three had small cell carcinoma, and the rest had large cell endocrine carcinoma. Tumor sizes (longitudinal diameter), measured by CT, of these 11 patients ranged from 6 mm to 52 mm (mean ± SD 8.3 mm ± 11.9 mm), and SUV_max for 1 h ranged from 3.37 to 11.1 (mean ± SD 6.12 ± 2.43). Three of these pancreatic lesions were difficult to determine by routine transaxial images, and detection was obvious only by thin-slice images or multiplanar reconstruction images. Contrast-enhanced CT showed gradual fill-in from the peripheral portion to the center. In addition, 10 of 11 cases did not show main pancreatic duct dilatation even if the tumor size was large. Conclusions  Metastases to the pancreas in lung cancer patients are not so rare and radiologists first have an important role to detect the pancreatic mass and then suggest to metastasis as the likely diagnosis. For this purpose, FDG-PET/CT has an advantage in depicting unsuspected pancreatic metastasis from lung cancer, particularly that which is not detected by CT alone.     

SPECT／CT对分化型甲状腺癌诊治的增益价值

目的：评价^131ISPECT／CT断层融合显像对全身平面显像（WBS）诊断不明确的分化型甲状腺癌（帆）诊治的增益价值。方法：对^131I治疗后WBS结果不明确的23例分化型甲状腺癌术后患者行^131ISPECT／CT融合显像,在病灶和患者两种水平上评价融合显像在DTC定位和／或定性诊断上的增益价值,同时分析SPECT／CT结果对治疗策略的影响。所有结果均通过病理、其他影像检查和临床随访予以证实。结果：在^131IWBS发现的总计232个摄碘灶中,甲状腺床占33．2％,恶性病灶占62．1％,非甲状腺生理性和良性摄取以及污染占4．7％。对^131IWBS无法确诊的81个摄碘灶共行37次SPECT／CT检查,后者获得准确定位和定性诊断的占85．2％和82．7％。17例（73．9％）患者获得了增益价值,其中8例（47．1％）患者的治疗方案发生了改变。结论：对全身平面显像（WBS）诊断不明确的分化型甲状腺癌（DTC）患者加做SPECT／CT断层融合显像在提高诊断正确率、减少伪影和调整治疗方案上具有重要临床价值。随着图像融合技术的不断进步,SPECT／CT将在DTC甚至其他疾病的诊治上发挥更大作用。     

Benign Schwannoma Mimicking Metastatic Lesion on F-18 FDG PET/CT in Differentiated Thyroid Cancer

We report a case of benign schwannoma mimicking metastatic carcinoma. A 55-year-old female with papillary thyroid carcinoma underwent total thyroidectomy. F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) demonstrated a focal hypermetabolic lesion with maximum standardized uptake value (SUVmax) 5.3 at the right chest wall. Conventional chest CT demonstrated a 5.4 cm ovoid mass lesion between the intercostal muscles and liver. Pathology revealed a schwannoma by tumor excision. This case demonstrates that benign schwannoma may demonstrate FDG uptake mimicking metastatic carcinoma.     

Value of 124I-PET/CT in staging of patients with differentiated thyroid cancer

The aim of this study is to evaluate the clinical significance of ¹²⁴I positron emission tomography (PET) using a combined PET/CT tomograph in patients with differentiated thyroid carcinoma and to compare the PET/CT results with ¹³¹I whole-body scintigraphy (WBS), dedicated PET and CT alone. Twelve thyroid cancer patients were referred for diagnostic workup and entered complete clinical evaluation, including histology, cytology, thyroglobulin level, ultrasonography, fluorine-18 fluorodeoxyglucose (FDG)-PET, FDG-PET/CT and CT. Lesion-based evaluation showed a lesion delectability of 56, 87 and 100% for CT, ¹²⁴I-PET, and combined ¹²⁴I-PET/CT imaging, respectively. Lesion delectability of ¹³¹I-WBS was 83%. We conclude that ¹²⁴I-PET/CT imaging is a promising technique to improve treatment planning in thyroid cancer. It is particularly valuable in patients suffering from advanced differentiated thyroid cancer prior to radio-iodine therapy and in patients with suspected recurrence and potential metastatic disease.     

Anatomo-metabolic characteristics of atelectasis in F-18 FDG-PET/CT imaging

PURPOSE: To evaluate the structural and metabolic characteristics of atelectasis in FDG-PET/CT. METHODS: Twenty one consecutive patients (13 males, 8 females, median age 67 years) with CT features of atelectasis, undergoing PET/CT imaging for preoperative staging of histologically proven malignancies (20 lung cancer and 1 ovarian cancer metastasis to lung), were included in the study. RESULTS: Hounsfield units of atelectasis (-383.58+/-189, range -631 to 82) were significantly higher than in normal lung (-756+/-67.46, range -839 to -555; P=0.0001), and lower than in malignant tissue (35+/-19, range 4-77; P=0.0001). The main patterns of FDG uptake observed in atelectasis were diffuse and homogenous. The standard uptake value (SUV) in atelectasis was low to moderate (SUV(avg): 1.13+/-0.50; SUV(max): 1.44+/-0.54), and generally lower than in tumor tissue (SUV(avg): 6.25+/-3.58, range 2.0-16.5), but always higher than in normal lung (0.56+/-0.18 and 0.70+/-0.23, respectively) (P=0.0001). There was a positive correlation between the density of atelectatic lesions and the degree of uptake, with no relationship to size. CONCLUSION: There is a positive relationship between the density of collapsed lung and the intensity of FDG uptake. FDG uptake in atelectasis is higher than in normal lung, and generally lower than in tumor tissue.     

Integrated FDG-PET/CT vs. standard radiological examinations: Comparison of capability for assessment of postoperative recurrence in non-small cell lung cancer patients

Purpose

The purpose of this study was to prospectively and directly compare diagnostic capabilities of whole-body integrated FDG-PET/CT and standard radiologic examination for assessment of recurrence in postoperative non-small cell lung cancer (NSCLC) patients.

Materials and methods

A total of 92 consecutive pathologically diagnosed NSCLC patients (65 males, 27 females; mean age, 71 years) underwent pathologically and surgically proven complete resection, followed by prospective whole-body FDG-PET/CT and standard radiological examinations. Final diagnosis of recurrence was based on the results of more than 1 year of follow-up and/or pathological examinations. On both methods, the probability of recurrence was assessed in each patient by using a five-point visual scoring system, and the each final diagnosis was made by consensus between two readers. Kappa analyses were performed to determine inter-observer agreement for both methods, and ROC analyses were used to compare capability of the two methods for assessment of postoperative recurrence on a per-patient basis. Sensitivity, specificity and accuracy were also compared between PET/CT and standard radiological examination by means of McNemar's test.

Results

All inter-observer agreements were almost perfect (integrated PET/CT: κ = 0.89; standard radiological examination: κ = 0.81). There were no statistically significant differences in area under the curve, sensitivity, specificity and accuracy between integrated FDG-PET/CT and standard radiologic examinations (p > 0.05).

Conclusion

Integrated FDG-PET/CT can be used for assessment of postoperative recurrence in NSCLC patients with accuracy as good as that of standard radiological examinations.     

Clinical implication of F-18 FDG PET/CT for differentiated thyroid cancer in patients with negative diagnostic iodine-123 scan and elevated thyroglobulin

This study aims to investigate the usefulness of F-18 FDG PET/CT in differentiated thyroid cancer (DTC) with elevated serum thyroglobulin (Tg) but negative iodine-123 (I-123) scan.     

Diagnosis of Cardiac Metastasis from Endometrial Cancer by F-18 FDG-PET/CT

We report a case of a 59-year-old woman with right ventricular metastasis of undifferentiated endometrial cancer. Cardiac metastasis from endometrial cancer is a very rare finding. The case demonstrates that undifferentiated endometrial cancer is capable of metastasizing, presumably through a hematogenous route, to unexpected distant organs. These unexpected sites should not be undermined in the restaging and surveillance of these patients.     

Performance profile of FDG-PET and PET/CT for cancer screening on the basis of a Japanese Nationwide Survey

Objective The aim of this study is to survey the situation of ¹⁸F-fluorodeoxyglucose-positron emission tomography (FDG-PET) cancer screening in Japan and to describe its performance profile. Methods “FDG-PET for cancer screening” was defined as FDG-PET or positron emission tomography and computed tomography (PET/CT) scan with or without other tests performed for cancer screening of healthy subjects. We sent questionnaires regarding FDG-PET cancer screening to 99 facilities in which FDG-PET tests were performed during the fiscal year 2005. Replies were obtained from 68 of the 99 facilities, of which 46 facilities performed FDG-PET cancer screening. The total number of subjects who underwent FDG-PET cancer screening was 50 558. From 38 of 46 facilities, reliable results of thorough examinations were obtained for the subjects who were positive by FDG-PET and/or one or more of the combined screening tests was performed and were referred for further evaluation. The total number of subjects in these 38 facilities amounted to 43 996. Results A total of 50 558 healthy subjects underwent FDG-PET (including PET/CT) scanning with or without other tests for cancer screening in 46 PET centers during the fiscal year of 2005 in Japan. Thorough examination was indicated for 9.8% of the cases as a result of positive findings suggesting possible cancer. On analyzing 43 996 cases from 38 PET centers from which detailed information was obtained, 500 cases of cancers (1.14%) were found, of which 0.90% were PET positive and 0.24% were PET negative, resulting in the relative sensitivity of PET being 79.0%. Cancers of the thyroid, colon/rectum, lung, and breast were most frequently found (107, 102, 79, and 35 cases, respectively) with high PET sensitivity (88%, 90%, 80%, and 92%). PET showed an overall positive predictive value of 29.0%. PET/CT had a better detection rate, sensitivity, and positive predictive value than dedicated PET (P < 0.01). Conclusions We were able to clarify the performance profile of “FDG-PET for cancer screening” on the basis of a Japanese nationwide survey. The number of facilities possessing PET is increasing steadily, highlighting the necessity of evaluating the usefulness of “FDG-PET cancer screening” as soon as possible by undertaking long-term investigations of large series of subjects.     

Integrated contrast-enhanced diagnostic whole-body PET/CT as a first-line restaging modality in patients with suspected metastatic recurrence of breast cancer

Objective(s)

Only few information exist about the diagnostic accuracy of PET/CT for restaging patients with metastatic recurrence of breast carcinoma. Therefore, our study hypothesis was to perform diagnostic contrast enhanced CT (ce-CT) and FDG-PET in a one-step investigation, to prove sensitivity of each modality and to determine whether diagnostic PET/CT adds information over PET or contrast enhanced CT alone for restaging of patients with suspected recurrence of breast cancer.

Methods

Fifty-two patients with suspected recurrence of breast cancer were included in our study. All of them were free of metastasis after the first line therapy. Indications for restaging were: Elevated tumor markers n = 32, clinical deterioration n = 16 and/or suspicious findings on other imaging studies n = 48. Integrated PET/CT was performed using contrast-enhanced diagnostic CT for attenuation correction.

Results

PET was correct in 44/52 patients (85%), ce-CT in 38/52 patients (73%) and PET/CT in 50/52 patients (96%). Sensitivity and specificity of lesion detection of PET, CT and PET/CT were 84%, 66% and 93%, and 100%, 92%, and 100%, respectively.

Discussion

PET/CT can improve staging and alter therapeutic options in patients suspected to have breast cancer recurrence and distant metastatic disease, primarily by demonstrating local or distant nodal involvement occult at other imaging studies. The added value of FDG-PET/CT over other diagnostic modalities is mainly expressed by the fact that a noninvasive whole-body evaluation is possible in a single examination.     

Performance of FDG-PET/CT in the diagnosis of recurrent endometrial cancer

Objective To evaluate the accuracy of integrated positron emission tomography and computed tomography (PET/CT) using 18-F-fluorodeoxyglucose (FDG), compared with PET alone, in the diagnosis of suspected endometrial cancer recurrence. Methods Thirty women who had undergone primary surgery for histopathologically proven endometrial cancer with suspected recurrence because of clinical, cytological, biochemical, and/or radiological findings were enrolled in this study. PET and integrated PET/CT images were evaluated by two different experienced radiologists by consensus for each modality. A final diagnosis of recurrence was confirmed by histopathology, other imaging and clinical follow-up for longer than 1 year. The statistical significance of differences between PET and PET/CT was determined by the McNemar test. Results Patient-based analysis showed that the sensitivity, specificity, and accuracy of PET/CT were 93% (14/15), 93% (14/15), and 93% (28/30), respectively, whereas for PET, the corresponding data were 80% (12/15), 80% (12/15), and 80% (24/30), respectively (P = 0.479, 0.479, and 0.134, respectively). CT from PET/CT resolved the false-positive PET results because of hyper-metabolic activity of benign inflammatory lesions and physiological variants and moreover detected lung metastasis and para-aortic lymph node metastasis that PET missed. However, tiny para-aortic lymph node metastasis could not be detected even with PET/CT. Conclusions Integrated FDG-PET/CT is a useful complementary modality for providing good anatomic and functional localization of sites of recurrence during follow-up of patients with endometrial cancer.