Erena Yamasaki

Accuracy of 18F-FDG PET/CT in Detecting Pelvic and Paraaortic Lymph Node Metastasis in Patients with Endometrial Cancer

OBJECTIVE The objective of our study was to evaluate the accuracy of integrated PET and CT (PET/CT) using (18)F-FDG in detecting pelvic and paraaortic lymph node metastasis in patients with endometrial cancer, using surgical and histopathologic findings as the reference standard. SUBJECTS AND METHODS Forty patients with clinical stages IA to IIIC underwent radical hysterectomy, including pelvic lymphadenectomy with or without paraaortic lymphadenectomy, after FDG PET/CT. Lymphadenectomy involved removing all visible lymph nodes in the surgical fields. PET/CT findings were interpreted by two experienced radiologists in consensus and compared with histopathologic results. The criterion for malignancy on PET/CT images was increased radiotracer uptake by a lymph node independent of node size. RESULTS In total, 62 pathologically positive nodes were found in 10 patients and 60 of 62 dissected metastatic nodes were identified on the CT component. The overall node-based sensitivity, specificity, and accuracy of PET/CT for detecting nodal metastases were 53.3% (32/60), 99.6% (1,419/1,424), and 97.8% (1,451/1,484), respectively. The sensitivity for detecting metastatic lesions 4 mm or less in diameter was 16.7% (4/24), that for lesions between 5 and 9 mm was 66.7% (14/21), and that for lesions 10 mm or larger was 93.3% (14/15). The overall patient-based sensitivity, specificity, and accuracy were 50% (5/10), 86.7% (26/30), and 77.5% (31/40), respectively. CONCLUSION Integrated FDG PET/CT is superior to conventional imaging techniques, but it is only moderately sensitive in predicting lymph node metastasis preoperatively in patients with endometrial cancer. Even PET/CT should not replace lymphadenectomy.

Diagnostic accuracy of integrated FDG-PET/contrast-enhanced CT in staging ovarian cancer: comparison with enhanced CT

PurposeThe purpose of the study is to evaluate the accuracy of integrated positron emission tomography and computed tomography (PET/CT) with 18F-fluorodeoxyglucose (FDG) with IV contrast for preoperative staging of ovarian cancer, in comparison with enhanced CT, using surgical and histopathological findings as the reference standard.Materials and methodsForty patients with ovarian cancer underwent FDG-PET/contrast-enhanced CT scans for staging before primary debulking surgery. PET/CT and the CT component separately, were interpreted by two experienced radiologists by consensus for each investigation. Status with regard to lesion inside and outside the pelvis was determined on the basis of histopathology. The significance of differences between the two imaging modalities was determined using the McNemar test.ResultsStaging revealed stage I in 18 patients (IA, n = 9; IB, n = 3; IC, n = 6), stage II in seven (IIA, n = 2; IIB, n = 3; IIC, n = 2), stage III in 14 (IIIA, n = 1; IIIB, n = 3; IIIC, n = 10), and stage IV in one. The results of CT and PET/CT were concordant with the final pathological staging in 22 out of 40 (55%) and 30 out of 40 (75%) cases, respectively. The overall lesion-based sensitivity improved from 37.6% (32 out of 85) to 69.4% (59 out of 85), specificity from 97.1% (578 out of 595) to 97.5% (580 out of 595), and accuracy from 89.7% (610 out of 680) to 94.0% (639 out of 680) between CT and PET/CT. There were significant differences in sensitivity and accuracy, with p values of 5.6 × 10−7 and 1.2 × 10−7, respectively.ConclusionIntegrated FDG-PET/contrast-enhanced CT is a more accurate imaging modality for staging ovarian cancer and useful for selecting appropriate treatment than enhanced CT.

Performance of FDG-PET/CT for diagnosis of recurrent uterine cervical cancer

The purpose is to evaluate the accuracy of integrated FDG-PET/CT, compared with PET alone, for diagnosis of suspected recurrence of uterine cervical cancer. Fifty-two women who had undergone treatment for histopathologically proven cervical cancer received PET/CT with suspected recurrence. PET-alone and integrated PET/CT images were evaluated by two different experienced radiologists by consensus for each investigation. A final diagnosis was confirmed by histopathology, radiological imaging, and clinical follow-up for over 1 year. Patient-based analysis showed that the sensitivity, specificity, and accuracy of PET/CT were 92.0% (23/25), 92.6% (25/27), and 92.3% (48/52), respectively, while for PET, the corresponding figures were 80.0% (20/25), 77.8% (21/27), and 78.8% (41/52), respectively. PET/CT resolved the false-positive PET results due to hypermetabolic activity of benign/inflammatory lesions and physiological variants, and was able to detect lung metastasis, local recurrence, peritoneal dissemination, para-aortic lymph node metastasis, and pelvic lymph node metastasis missed by PET alone. However, tiny local recurrence and lymph node metastasis could not be detected even by PET/CT. 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 cervical cancer.

Performance of Integrated FDG-PET/Contrast-enhanced CT in the Diagnosis of Recurrent Pancreatic Cancer: Comparison with Integrated FDG-PET/Non-contrast-enhanced CT and Enhanced CT

PurposeThe purpose of this study is to evaluate the accuracy of 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET)/computed tomography (CT) with intravenous contrast for depiction of recurrent pancreatic cancer, compared with PET/non-enhanced CT and CT.ProcedureForty-five patients previously treated for pancreatic cancer underwent PET/CT for suspected recurrence. Lesion status was determined on the basis of histopathology and radiological imaging follow-up.ResultsPatient-based analysis showed that sensitivity, specificity, and accuracy of PET/contrast-enhanced CT were 91.7%, 95.2%, and 93.3%, respectively, whereas those of PET/non-enhanced CT were 83.3%, 90.5%, and 86.7%, respectively, and those of enhanced CT were 66.7%, 85.7%, and 75.6%, respectively. In 21 patients whom the final diagnosis was obtained from the histopathologic examination, those figures of PET/contrast-enhanced CT were 94.7%, 50.0%, and 90.4%, respectively. The sensitivity of PET/contrast-enhanced CT in detecting local recurrence, abdominal lymph node metastasis, and peritoneal dissemination were 83.3%, 87.5%, and 83.3%, respectively.ConclusionPET/contrast-enhanced CT is an accurate modality for assessing recurrence of pancreatic cancer.

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

ObjectiveTo 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.MethodsThirty 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.ResultsPatient-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.ConclusionsIntegrated 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.

Standardized uptake values of uterine leiomyoma with 18F-FDG PET/CT: Variation with age, size, degeneration, and contrast enhancement on MRI

ObjectiveTo assess the effect of age, size, the degree of degeneration, and contrast enhancement on magnetic resonance imaging (MRI) on 18F-fluoro-2-deoxyglucose (18F-FDG) uptake in uterine leiomyomas using quantitative standardized uptake values (SUVs).MethodsA total of 61 leiomyomas of 41 patients, who underwent combined positron emission tomography/computed tomography (PET/CT) using 18F-FDG and contrast-enhanced MRI were included in this study. Sixty-one leiomyomas were divided into two groups: “non-degenerated” leiomyomas showing distinct low signal intensity on T2-weighted images and intermediate signal intensity on T1-weighted images, and “degenerated” leiomyomas showing other types of signal intensity. Sixty-one leiomyomas were also divided into two groups of “strongly enhancing” leiomyomas and “weakly enhancing” leiomyomas in terms of their degree of contrast enhancement on MRI.ResultsThe mean values of the maximum and average SUVs for the total of 61 leiomyomas were 2.34 ± 0.75 (range 1.59–5.15) and 1.74 ± 0.50 (0.66–3.95), respectively. There was a moderate negative correlation between the maximum and average SUVs and age (r = −0.43 and P = 0.00016, r = −0.31 and P = 0.029, respectively). Although there was a mild positive correlation between maximum SUV and size (r = 0.35 and P = 0.011), there was no significant difference between average SUV and size. Although there was no significant difference in average SUV between “degenerated” and “non-degenerated” leiomyomas, the maximum SUV of “degenerated” leiomyomas was significantly higher than that of “non-degenerated” leiomyomas (P = 0.0012). The degree of contrast enhancement on MRI was not significantly correlated with 18F-FDG uptake.ConclusionsMild or moderate uptake of 18F-FDG is often observed in uterine leiomyoma and declines with age, and should not be confused with malignant accumulation.

Comparison of DWI and PET/CT in evaluation of lymph node metastasis in uterine cancer

AIM To investigate diffusion-weighted imaging (DWI) and positron emission tomography and computed tomography (PET/CT) with IV contrast for the preoperative evaluation of pelvic lymph node (LN) metastasis in uterine cancer. METHODS Twenty-five patients with endometrial or cervical cancer who underwent both DWI and PET/CT before pelvic lymphadenectomy were included in this study. For area specific analysis, LNs were divided into eight regions: both common iliac, external iliac, internal iliac areas, and obturator areas. The classification for malignancy on DWI was a focally abnormal signal intensity in a location that corresponded to the LN chains on the T1WI and T2WI. The criterion for malignancy on PET/CT images was increased tracer uptake by the LN. RESULTS A total of 36 pathologically positive LN areas were found in 9 patients. With DWI, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy for detecting metastatic LNs on an LN area-by-area analysis were 83.3%, 51.2%, 27.3%, 93.3% and 57.0%, respectively, while the corresponding values for PET/CT were 38.9%, 96.3%, 70.0%, 87.8% and 86.0%. Differences in sensitivity, specificity and accuracy were significant (P < 0.0005). CONCLUSION DWI showed higher sensitivity and lower specificity than PET/CT. Neither DWI nor PET/CT were sufficiently accurate to replace lymphadenectomy.