An update on the role of PET/CT and PET/MRI in ovarian cancer

This review article summarizes the role of PET/CT and PET/MRI in ovarian cancer. With regard to the diagnosis of ovarian cancer, the presence of FDG uptake within the ovary of a postmenopausal woman raises the concern for ovarian cancer. Multiple studies show that FDG PET/CT can detect lymph node and distant metastasis in ovarian cancer with high accuracy and may, therefore, alter the management to obtain better clinical outcomes. Although PET/CT staging is superior for N and M staging of ovarian cancer, its role is limited for T staging. Additionally, FDG PET/CT is of great benefit in evaluating treatment response and has prognostic value in patients with ovarian cancer. FDG PET/CT also has value to detect recurrent disease, particularly in patients with elevated serum CA-125 levels and negative or inconclusive conventional imaging test results. PET/MRI may beneficial for tumor staging because MRI has higher soft tissue contrast and no ionizing radiation exposure compared to CT. Some non-FDG PET radiotracers such as ¹⁸F-fluorothymidine (FLT) or ¹¹C-methionine (MET) have been studied in preclinical and clinical studies as well and may play a role in the evaluation of patients with ovarian cancer.     

Usefulness of FDG PET for assessment of early recurrent epithelial ovarian cancer

OBJECTIVE: The purpose of our study was to evaluate the diagnostic accuracy of FDG positron emission tomography (PET) in comparison with CT in detecting recurrent ovarian carcinoma and its ability to reveal small tumor recurrence. MATERIALS AND METHODS: We reviewed the records of 31 consecutive patients with pathologically proven epithelial carcinoma who underwent FDG PET 1 month before second-look surgery to assess recurrent tumor. Of these 31 patients, 21 patients also underwent CT 1 month before second-look surgery. The diagnostic accuracies of FDG PET (n = 31), CT (n = 21), and combined FDG PET and CT (n = 21) in detecting recurrent tumor were calculated and compared with each other using the Bennett's test in 21 patients who underwent both imaging studies. Detection rates of individual tumors relative to their sizes were compared between FDG PET and CT using the McNemar test. RESULTS: The sensitivity, specificity, and accuracy of FDG PET, CT, and combined FDG PET and CT for revealing recurrent ovarian cancer were 45.3%, 99.7%, 91.0%; 54.5%, 99.6%, 91.7%; 58.2%, 99.6%, 92.4%, respectively. We found no statistically significant difference in the diagnostic accuracy of FDG PET, CT, and combined FDG PET and CT (chi(2) < 5.991). Detection rates of tumor nodules found on CT were significantly greater than those on FDG PET when nodule size was 0.3-0.7 cm (p < 0.05). CONCLUSION: FDG PET did not improve the overall diagnostic accuracy in detecting recurrent ovarian carcinoma compared with CT. Rather, FDG PET was inferior to CT in its ability to reveal small-tumor recurrence.     

Noninvasive and invasive staging of ovarian cancer: review of the literature

The use of F-18 FDG PET/CT in the characterization of doubtful adnexal findings and in the staging of ovarian cancer is being extensively evaluated. The purpose of our article is to review the literature and to add our experience to the published works. We concluded that F-18 FDG PET/CT could represent an important method in addition to other imaging modalities (transvaginal ultrasound-, and contrast-enhanced computed tomography) in the characterization of adnexal masses and in the staging of ovarian cancer patients, particularly in assessing the presence of extra-abdominal metastatic spread.     

Improved detection of individual nodal involvement in squamous cell carcinoma of the esophagus by FDG PET.

Because both the number and location of metastatic lymph nodes and the N stage influence survival in esophageal cancer, accurate noninvasive evaluation of individual lymph node groups for the presence of metastasis is essential for therapeutic planning. Therefore, we investigated the accuracy of FDG PET for evaluating individual lymph groups in esophageal cancer patients and compared the results with those of CT and endoscopic sonography (ES). METHODS: Sixty-one consecutive patients with histologically proven primary esophageal carcinoma were studied prospectively with FDG PET. Thirteen patients who were treated nonsurgically were excluded from data analysis. The remaining 48 patients underwent esophagectomy and lymph node dissection. All 48 patients underwent CT scanning, including the lower neck, thorax, and upper abdomen, with intravenous administration of contrast medium. ES was performed in 45 of the patients but was incomplete in 12 patients because of esophageal stenosis. The accuracies of FDG PET, CT, and ES were compared with histologic findings. RESULTS: During surgery, a total of 382 lymph node groups were dissected in 48 patients, of which 100 node groups in 32 patients were malignant on histologic examination. For assessing metastasis to individual groups, FDG PET showed 57% sensitivity, 97% specificity, and 86% accuracy, whereas CT showed 18% sensitivity (P < 0.0001), 99% specificity (P = 0.033), and 78% accuracy (P = 0.003). For N staging, FDG PET was correct in 83% (40/48) of the patients, whereas CT and ES were correct in 60% (29/48; P = 0.006) and 58% (26/45; P = 0.003), respectively. CONCLUSION: FDG PET is more accurate than is CT or ES for evaluating metastasis to individual lymph node groups and for N staging in esophageal cancer and thus may be helpful in determining the therapeutic plan.     

Whole-body FDG PET/CT is more accurate than conventional imaging for staging primary breast cancer patients

Purpose

This retrospective study aimed (1) to compare the diagnostic accuracy of whole-body FDG PET/CT for initial breast cancer staging with the accuracy of a conventional, multimodal imaging algorithm, and (2) to assess potential alteration in patient management based on the FDG PET/CT findings.

Methods

Patients with primary breast cancer (106 women, mean age 57?±?13?years) underwent whole-body FDG PET/CT and conventional imaging (X-ray mammography, MR mammography, chest plain radiography, bone scintigraphy and breast, axillary and liver ultrasonography). The diagnostic accuracies of FDG PET/CT and a conventional algorithm were compared. Diagnostic accuracy was assessed in terms of primary tumour detection rate, correct assessment of primary lesion focality, T stage and the detection rates for lymph node and distant metastases. Histopathology, imaging or clinical follow-up served as the standards of reference.

Results

FDG PET/CT was significantly more accurate for detecting axillary lymph node and distant metastases (p?=?0.0125 and p?Conclusion Full-dose, intravenous contrast-enhanced FDG PET/CT was more accurate than conventional imaging for initial breast cancer staging due to the higher detection rate of metastases and synchronous tumours, although the study had several limitations including a retrospective design, a possible selection bias and a relevant false-positive rate for the detection of axillary lymph node metastases. FDG PET/CT resulted in a change of treatment in a substantial proportion of patients.     

Diagnostic accuracy of 18F-FDG PET/CT in characterizing ovarian lesions and staging ovarian cancer: correlation with transvaginal ultrasonography, computed tomography, and histology

AIMS: To (a) assess the accuracy of 18F-FDG PET/CT in distinguishing malignant from benign pelvic lesions, compared to transvaginal ultrasonography (TVUS) and (b) to establish the role of whole-body 18F-FDG PET/CT, compared to contrast enhanced computed tomography (CT), in staging patients with ovarian cancer. PATIENTS: Fifty consecutive patients with a pelvic lesion, already scheduled for surgery on the basis of physical examination, TVUS, and serum Ca125 levels, were enrolled in the study. Patients' age ranged between 23 and 89 years (mean 64). All patients underwent TVUS including a colour Doppler study followed by a thorax and abdominal CT scan, and whole-body 18F-FDG PET/CT within 2 weeks prior to surgery. Histological findings obtained at surgery were taken as the 'gold standard' to compare 18F-FDG PET/CT and TVUS, and 18F-FDG PET/CT vs. CT. When tissue analysis showed ovarian cancer, the accuracy of 18F-FDG PET/CT and CT were compared for the purpose of obtaining a precise staging. RESULTS: At surgery, the ovarian lesions were malignant in 32/50 patients (64%) and benign in the remaining 18/50 patients (36%). The sensitivity, specificity, NPV, PPV and accuracy of 18F-FDG PET/CT were 87%, 100%, 81%, 100% and 92%, respectively, compared with 90%, 61%, 78%, 80% and 80%, respectively, for TVUS. In staging ovarian cancer, 18F-FDG PET/CT results were concordant with final pathological staging in 22/32 (69%) patients while CT results were concordant in 17/32 (53%) patients. CT incorrectly down-staged four out of six stage IV patients by missing distant metastasis in the liver, pleura, mediastinum, and in left supraclavicular lymph nodes, which were correctly detected by 18F-FDG PET/CT. CONCLUSION: PET/CT with 18F-FDG provides additional value to TVUS for the differential diagnosis of benign from malignant pelvic lesions, and to CT for the staging of ovarian cancer patients.     

Advantages and limitations of FDG PET in the follow-up of breast cancer

18F-Fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) has been evaluated in breast cancer for the characterisation of primary tumours, lymph node staging and the follow-up of patients after surgery, chemotherapy and/or external radiotherapy. In contrast to both the low sensitivity and moderate specificity of FDG PET in the initial detection and characterisation of breast cancer and the low lesion-based sensitivity for lymph node staging, the results from use of FDG PET in re-staging breast cancer patients are very promising. A major advantage of FDG PET imaging compared with conventional imaging is that it screens the entire patient for local recurrence, lymph node metastases and distant metastases during a single whole-body examination using a single injection of activity, with a reported average sensitivity and specificity of 96% and 77%, respectively. In most studies the sensitivity of FDG PET is higher than that of a combination of conventional imaging methods. Limitations of FDG PET in the follow-up of breast cancer patients include the relatively low detection rate of bone metastases, especially in case of the sclerotic subtype, and the relatively high rate of false positive results. The rather low specificity of FDG PET can be improved/increased by utilising combined anatomical-molecular imaging techniques, such as a PET/CT tomograph. First results using PET/CT imaging in the follow-up of breast cancer patients demonstrate increased specificity compared with FDG PET alone. Both imaging modalities, however, offer to detect recurrent and metastatic breast cancer disease at an early stage and thus continue to demonstrate the efficacy of molecular imaging in patient management, despite the limited therapeutic options in recurrent and metastatic breast cancer.     

Serum tumor markers and PET/CT imaging for tumor recurrence detection

When confronted with a suspicious rise in CA 15.3 in asymptomatic breast cancer patients following primary treatment and negative or equivocal conventional imaging findings, FDG PET/CT allows assessment of the site and extent of the recurring disease with an accuracy of 83 %. Both FDG PET and FDG PET/CT are superior when compared to CT alone for the purpose of recurrence detection in patients suffering from ovarian carcinoma who have completed primary therapy but demonstrate a rising serum CA-125 level. As the global accuracy of CT alone for detection of recurrence of ovarian cancer approximates 80 %, CT scan should be performed upfront to identify the site of recurrence. When confronted with negative or equivocal CT findings, FDG PET alone or FDG PET/CT should be added. In patients with rising serum CEA levels that have undergone primary treatment for a colorectal carcinoma, both FDG PET and FDG PET/CT allow detection of tumor recurrence with an accuracy of 95 %, well above that of CT and MRI. Available studies further suggest that FDG/PET findings will affect treatment management in 28–50 % of these patients. The detection rate of both 11C-choline and 18F-choline PET and PET/CT for local, regional, and distant recurrence in prostate carcinoma patients with a biochemical recurrence increases with rising PSA value at the time of imaging and reaches about 75 % in patients with PSA >3 ng/mL. Furthermore, PET and PET/CT with [¹¹C]- and [¹⁸F]-choline derivates may be helpful in the clinical setting for optimization of individualized treatment.     

18F-FDG PET/CT在宫颈癌诊断中的应用

目的 探讨18F-脱氧葡萄糖(FDG) PET/CT在宫颈癌诊断及其复发、转移灶探测中的应用价值.方法 88例患者行腹部或全身18F-FDG PET/CT显像,其中初诊者30例(宫颈良性病变11例,宫颈癌19例),宫颈癌治疗后58例.病灶根据病理检查、多种影像诊断技术及临床随访确诊,随访时间均为6个月～3年.结果 30例初诊者中,PET/CT诊断宫颈癌的灵敏度、特异性和准确性分别为17/19,10/11和27/30(90.0%).58例治疗后患者中,11例存在肿瘤复发或残余,PET/CT诊断肿瘤复发、残余的灵敏度、特异性和准确性分别为10/11,47/47(100.0%)和57/58(98.3%).41例有肿瘤转移,PET/CT诊断转移灶的灵敏度、特异性和准确性分别为92.7%,88.9%和90.9%;转移灶以盆腹腔淋巴结为主,39.0%有盆腔淋巴结转移,27.3%有腹膜后淋巴结转移,所有淋巴结转移患者中PET/CT发现26.8%病灶直径＜1.0cm.28.6%(22/77)的患者PET/CT发现腹腔外远处转移灶.18例输尿管梗阻患者中,16例PET/CT发现为肿瘤侵犯压迫所致.结论 18F-FDG PET/CT显像在宫颈癌的诊断及其复发、转移灶探测中有良好的应用价值,尤其是对远处转移灶和小淋巴结转移灶的检测,可使临床分期更准确.     

Comparative study of FDG PET/CT and conventional imaging in the staging of rhabdomyosarcoma

Objective  The current study was conducted to compare the diagnostic accuracy between ¹⁸F-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/computed tomography (CT), and conventional imaging (CI) for the staging and re-staging of patients with rhabdomyosarcomas. Methods  Thirty-five patients who underwent FDG PET/CT prior to treatment were evaluated retrospectively. CI methods consisted of ^99mTc-hydroxymethylene diphosphonate bone scintigraphy, chest radiograph, whole body CT, and magnetic resonance imaging of the primary site. The images were reviewed and two boardcertified radiologists reached a diagnostic consensus. Tumor stage was confirmed by histological examination and/or follow-up examinations. Results  Interpretation on the basis of FDG PET/CT, and CI, diagnostic accuracies of the T and N stages were similar. Using FDG PET/CT, the M stage was correctly assigned in 31 patients (89%), whereas the accuracy of CI in M stage was 63%. TNM stage was correctly assessed with FDG PET/CT in 30 of 35 patients (86%) and with CI in 19 of 35 patients (54%). The overall TNM staging and M staging accuracies of FDG PET/CT were significantly higher than that of CI (P < 0.01). Conclusions  FDG PET/CT is more accurate than CI regarding clinical staging and re-staging of patients with rhabdomyosarcomas.     

Gamma camera coincidence imaging with [18F]fluorodeoxyglucose in the pretreatment evaluation of patients with oesophageal cancer

This study investigated the role of [18F]fluorodeoxyglucose (FDG) dual-head gamma camera coincidence imaging (GCI) in the pretreatment evaluation of patients with oesophageal cancer. Twenty-two patients (20 men; mean age, 64 years) with untreated, biopsy proven squamous cell carcinoma of the oesophagus underwent positron emission tomography (PET) and GCI 1 and 3 h after a single injection of FDG, respectively. Computed tomography (CT) was performed within 2 weeks of the FDG imaging. The sensitivity of lesion detection was compared between GCI and PET. Regional (N) and distant (M) metastases detected by GCI were evaluated with reference to PET and CT. The staging obtained by each modality was also compared with pathological staging in nine patients who underwent surgery. FDG PET detected 22 primary tumours, 34 metastatic lymph nodes and four organ metastases. Of them, GCI detected all primary tumours, 24 (71%) metastatic lymph nodes, and none of the organ metastases. Lymph nodes missed by GCI were smaller in size and the majority of them were located in the thoracic region. GCI provided N and M staging identical to CT and PET in eight patients and improved staging over CT in four patients. On the other hand, GCI missed metastases detected by both PET and CT in five patients. The addition of GCI to CT could improve detection of patients with metastasis to 82% (18/22) compared with 64% (14/22) detected by CT alone. In patients with pathological staging (n = 9), GCI could influence management changes in two patients (22%). In conclusion, FDG GCI has a role that is complementary to CT in the initial staging of patients with oesophageal cancer, and due to the additional detection of nodal metastasis, GCI can provide staging information, which may influence changes in management.     

Efficiency of [<Superscript>18</Superscript>F]FDG PET in characterising renal cancer and detecting distant metastases: a comparison with CT

The purpose of this study was to assess the efficiency of fluorine-18 fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) in the characterisation and primary staging of suspicious renal masses, in comparison with computed tomography, the current standard imaging modality. Fifty-three FDG PET studies were performed within the framework of a prospective study: 35 for both characterisation and staging of a suspicious mass, and 18 for staging early after surgical removal of a renal cancer. In the characterisation of renal masses, a high rate of false negative results was observed, leading to a sensitivity, specificity and accuracy of 47%, 80% and 51% respectively, versus 97%, 0/5 and 83% respectively for CT. FDG PET detected all the sites of distant metastasis revealed by CT, as well as eight additional metastatic sites, leading to an accuracy of 94% versus 89% for CT. However, 36/53 patients (68%) did not have any distant metastasis on either CT or on PET. All but one of these patients had a low Fuhrman histological grade and a limited local stage (pT2). We conclude that FDG PET does not offer any advantage over CT for the characterisation of renal masses but that it appears to be an efficient tool for the detection of distant metastasis in renal cancer. However, our data suggest that a selection process could be implemented to determine which patients should undergo PET. FDG PET could be performed in the event of a solitary metastasis or doubtful images on CT. Selection could also be based on adverse histological findings from nephrectomy specimens in order to perform staging early after nephrectomy.     

Optimal interpretation of FDG PET in the diagnosis, staging and management of pancreatic carcinoma.

This study had two purposes: to optimize the semiquantitative interpretation of 18F-fluorodeoxyglucose (FDG) PET scans in the diagnosis of pancreatic carcinoma by analyzing different cutoff levels for the standardized uptake value (SUV), with and without correction for serum glucose level (SUV(gluc)); and to evaluate the usefulness of FDG PET when used in addition to CT for the staging and management of patients with pancreatic cancer. METHODS: Sixty-five patients who presented with suspected pancreatic carcinoma underwent whole-body FDG PET in addition to CT imaging. The PET images were analyzed visually and semiquantitatively using the SUV and SUV(gluc). The final diagnosis was obtained by pathologic (n = 56) or clinical and radiologic follow-up (n = 9). The performance of CT and PET at different cutoff levels of SUV was determined, and the impact of FDG PET in addition to CT on patient management was reviewed retrospectively. RESULTS: Fifty-two patients had proven pancreatic carcinoma, whereas 13 had benign lesions, including chronic pancreatitis (n = 10), benign biliary stricture (n = 1), pancreatic complex cyst (n = 1) and no pancreatic pathology (n = 1). Areas under receiver operating characteristic curves were not significantly different for SUV and SUV(gluc). Using a cutoff level of 3.0 for the SUV, FDG PET had higher sensitivity and specificity than CT in correctly diagnosing pancreatic carcinoma (92% and 85% versus 65% and 61%). There were 2 false-positive PET (chronic pancreatitis, also false-positive with CT) and 4 false-negative PET (all with true-positive CT, abnormal but nondiagnostic) examinations. There were 5 false-positive CT (4 chronic pancreatitis and 1 pancreatic cyst) and 18 false-negative CT (all with true-positive FDG PET scans) examinations. FDG PET clarified indeterminate hepatic lesions or identified additional distant metastases (or both) in 7 patients compared with CT. Overall, FDG PET altered the management of 28 of 65 patients (43%). CONCLUSION: FDG PET is more accurate than CT in the detection of primary tumors and in the clarification and identification of hepatic and distant metastases. The optimal cutoff value of FDG uptake to differentiate benign from malignant pancreatic lesions was 2.0. Correction for serum glucose did not significantly improve the accuracy of FDG PET. Although FDG PET cannot replace CT in defining local tumor extension, the application of FDG PET in addition to CT alters the management in up to 43% of patients with suspected pancreatic cancer.     

Bildgebende Diagnostik im Staging gynäkologischer Karzinome

The prognosis in patients with gynecologic cancers depends not only on the stage but also on a wide spectrum of other findings. Cross-sectional imaging modalities, including sonography, CT and MRI, have increasingly been used for optimal treatment planning in gynecologic cancers. Their staging criteria are based on the well-established FIGO staging system. CT and MRI compete with sonography, which plays a pivotal role in the evaluation of the female pelvis. This paper reviews the role of sonography, CT and MRI in the staging of gynecologic malignancies. It puts the emphasis on MRI, which has been established as imaging modality of choice in the preoperative evaluation of cervical and endometrial cancer, and which seems slightly superior to CT in the staging of ovarian cancer.     

Staging non-small cell lung cancer with whole-body PET.

PURPOSE: To compare the accuracies of whole-body 2-[fluorine 18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) and conventional imaging (thoracic computed tomography [CT], bone scintigraphy, and brain CT or magnetic resonance [MR] imaging) in staging bronchogenic carcinoma. MATERIALS AND METHODS: Within 20 months, 100 patients with newly diagnosed bronchogenic carcinoma underwent whole-body FDG PET and chest CT. Ninety of these patients underwent radionuclide bone scintigraphy, and 70 patients underwent brain CT or MR imaging. For each patient, all examinations were completed within 1 month. A radiologic stage was assigned by using PET and conventional imaging independently and was compared with the pathologic stage. The accuracy, sensitivity, specificity, and negative and positive predictive values were calculated. RESULTS: PET staging was accurate in 83 (83%) patients; conventional imaging staging was accurate in 65 (65%) patients (P < .005). Staging with mediastinal lymph nodes was correct by using PET in 67 (85%) patients and by using CT in 46 (58%) patients (P < .001). Nine (9%) patients had metastases demonstrated by using PET that were not found with conventional imaging, whereas 10 (10%) patients suspected of having metastases because of conventional imaging findings were correctly shown with PET to not have metastases. CONCLUSION: Whole-body PET was more accurate than thoracic CT, bone scintigraphy, and brain CT or MR imaging in staging bronchogenic carcinoma.     

Staging of non-small-cell lung cancer by whole-body fluorine-18 deoxyglucose positron emission tomography

Positron emission tomography (PET) using fluorine-18 deoxyglucose (FDG), showing increased FDG uptake and retention in malignant cells, has been proven useful to differentiate malignant from benign tissue. We undertook a prospective study in 61 patients to compare the accuracy of whole-body FDG PET and conventional imaging (CI) methods for the staging of nonsmall-cell lung cancer (NSCLC). CI included chest and abdomen computed tomographic scanning and bone scintigraphy. When CI or PET study suggested metastatic disease, confirmation was obtained by biopsy or clinical or radiological follow-up. As compared to CI, PET correctly changed the N stage in 13 patients (21%) and the M stage in six patients (10%). There were three false-positive and no false-negative distant PET findings. Our preliminary results show that whole-body FDG PET can improve the diagnostic accuracy in the staging of NSCLC.     

18F-FDG PET/CT显像对妇科肿瘤诊断和术后监测的应用

目的探讨^18F-脱氧葡萄糖（FDG）PET／CT显像诊断妇科肿瘤和术后监测的价值。方法回顾性分析30例已证实为妇科恶性肿瘤患者的^18F-FDGPET／CT显像结果。分2组：第1组16例，术前怀疑恶性肿瘤，行PET／CT进行诊断分期；第2组14例，术后6个月～2年不等，行多次化疗或放疗，用PET／CT监测有无复发或转移。结果由手术病理检查和随访证实。结果第1组16例患者中PET／CT诊断15例阳性，其中7例显示有局部淋巴结转移，最小直径约0．6cm；有l例假阴性。第2组14例患者中PET／CT显示10例共14处复发或转移，直径0．8～3．0cm。无假阳性。结论PET／CT显像可用于妇科肿瘤的早期诊断和术后监测。     

Whole-body FDG positron emission tomographic imaging for staging esophageal cancer comparison with computed tomography

PURPOSE: The aim of the authors in this study was to critically evaluate the role of whole-body positron emission tomographic (PET) imaging with fluorine-18 fluorodeoxyglucose (FDG) in staging esophageal cancer, and further to compare this method with conventional imaging with computed tomography (CT). MATERIALS AND METHODS: The authors performed independent, blinded retrospective evaluations of FDG PET images obtained in 47 patients referred for the initial staging of esophageal cancer before minimally invasive surgical staging. Twenty PET studies from patients with nonesophageal thoracic cancers were randomly selected for inclusion in the PET readings. In a subset of 37 of 47 cases, the PET findings were compared with independent readings of CT studies acquired within the same 6-week interval. The utility of the imaging findings was evaluated using a high-sensitivity interpretation (i.e., assigning equivocal findings as positive) and a low-sensitivity interpretation (i.e., assigning equivocal findings as negative). RESULTS: PET was less sensitive (41% in high-sensitivity mode, 35% in low-sensitivity mode) than CT (63% to 87%) for diagnosing tumor involvement in locoregional lymph nodes, which was identified by surgical assessment in 72% of patients. Notable, however, was the greater specificity of PET-determined nodal sites (to approximately 90%) compared with CT (14% to 43%). In detecting histologically proved distant metastases (n = 10), PET performed considerably better when applied in the high-sensitivity mode, with a sensitivity rate of approximately 70% and a specificity rate of more than 90% in the total group and in the subset of patients with correlative CT data. In the low-sensitivity mode, CT identified only two of seven metastatic sites, whereas the high-sensitivity mode resulted in an unacceptably high rate of false-positive readings (positive predictive value, 29%). PET correctly identified one additional site of metastasis that was not detected by CT. CONCLUSIONS: The relatively low sensitivity of PET for identifying locoregional lesions precludes its replacement of conventional CT staging. However, the primary advantage of PET imaging is its superior specificity for tumor detection and improved diagnostic value for distant metastatic sites, features that may substantially affect patient management decisions. In conclusion, PET imaging is useful in the initial staging of esophageal cancer and provides additional and complementary information to that obtained by CT imaging.     

Value of (18F)-FDG positron emission tomography, computed tomography, and magnetic resonance imaging in diagnosing primary and recurrent ovarian carcinoma

The aim of this study was to compare prospectively the accuracy of whole-body positron emission tomography (PET), CT and MRI in diagnosing primary and recurrent ovarian cancer. Nineteen patients (age range 23–76 years) were recruited with suspicious ovarian lesions at presentation (n = 8) or follow-up for recurrence (n = 11). All patients were scheduled for laparotomy and histological confirmation. Whole-body PET with FDG, contrast-enhanced spiral CT of the abdomen, including the pelvis, and MRI of the entire abdomen were performed. Each imaging study was evaluated separately. Imaging findings were correlated with histopathological diagnosis. The sensitivity, specificity and accuracy for lesion characterization in patients with suspicious ovarian lesions (n = 7) were, respectively: 100, 67 and 86 % for PET; 100, 67 and 86 % for CT; and 100, 100 and 100 % for MRI. For the diagnosis of recurrent disease (n = 10), PET had a sensitivity of 100 %, specificity of 50 % and accuracy of 90 %. The PET technique was the only technique which correctly identified a single transverse colon metastasis. Results for CT were 40, 50 and 43 %, and for MRI 86, 100 and 89 %, respectively. No statistically significant difference was seen. Neither FDG PET nor CT nor MRI can replace surgery in the detection of microscopic peritoneal disease. No statistically significant difference was observed for the investigated imaging modalities with regard to lesion characterization or detection of recurrent disease; thus, the methods are permissible alternatives. The PET technique, however, has the drawback of less accurate spatial assignment of small lesions compared with CT and MRI. Received: 9 April 1999; Revised: 22 June 1999; Accepted: 25 August 1999     

Contribution of PET in the detection of liver metastases from pancreatic tumours

AIM: Although uptake of 2-deoxy-2-[fluorine-18]fluoro-D-glucose (FDG) in the liver is basically high, metastatic liver tumours are known to be positive on positron emission tomography (PET). The purpose of this study is to evaluate the diagnostic accuracy of FDG-PET in detecting hepatic metastases from pancreatic cancer. METHODS: Thirty-four patients with histologically proven malignant tumours of the pancreas underwent FDG-PET, computed tomography (CT) and transabdominal ultrasound (US). The findings of PET, CT and US were compared with the histopathologic findings at surgery or with clinical follow-up and the diagnostic accuracy of PET was evaluated. RESULTS: PET showed 28 regions of high FDG uptake (SUV = 3.3-9.1) in 13 patients. Twenty-six foci were metastatic lesions confirmed by surgery (n = 11), clinical follow-up (n = 10) or autopsy (n = 5). FDG-PET accurately differentiated seven metastatic lesions from cysts when the diagnosis by US or CT was unreliable because of the small size of the lesion. In two patients who had areas of high uptake in the liver, no metastases were detected by surgery. FDG-PET showed no areas of increased uptake in 21 patients. Surgery revealed no metastatic lesions in the liver in 20 of 21 patients, but a liver metastasis was found at surgery in one patient. The diagnostic accuracy of FDG-PET was 90%, which was comparable with that of US or CT. CONCLUSION: Our data suggest that PET is reliable in detecting liver, metastases from pancreatic cancer.