Impact of PET/CT in comparison with same day contrast enhanced CT in breast cancer management

PURPOSE: To evaluate the impact of F-18 fluorodeoxyglucose (FDG) positron emission tomography with fused computerized tomography (PET/CT) in comparison with same day contrast enhanced CT (CE-CT) in breast cancer management. METHOD: Seventy studies in 49 breast cancer patients, 17 for initial and 53 for restaging disease were included. All patients underwent PET/CT for diagnostic purposes followed by CE-CT scans of selected body regions. PET/CT was started approximately 90 minutes following IV injection of 10-15 mCi of F-18 FDG on a GE Discovery PET/CT system. Oral contrast was given before F-18 FDG injection. The CE-CT was performed according to departmental protocol. RESULTS: Out of a total of 257 lesions, 210 were concordant between PET/CT and CE-CT. There were 47 discordant lesions, which were verified by either biopsy (35) or follow-up (12 PET positive CE-CT negative lesions). PET/CT correctly identified 25 true positive (TP). CE-CT identified 2 TP lesions missed by PET/CT which were false negatives (FNs): one liver metastasis with necrosis, which was nonavid to FDG uptake because of necrosis and a second one missed on abdominal metastatic node, which did not change staging or treatment. PET/CT incorrectly identified 2 false positive lesions while CE-CT incorrectly identified 18 false positive. TP recurrence of the disease was found by PET/CT in 44% (15/34 pts), whereas 56% (19/34 pts) were free of disease. The CE-CT described progression of the disease in 1 true negative PET/CT study and no progression in 2 TP PET/CT studies. The sensitivity, specificity, accuracy, positive productive value, and negative productive value for PET/CT were 97.8%, 93.5%, 97.3%, 99.1%, 85% and for CE-CT were 87.6%, 42%, 82.1%, 91.6%, 31.7%. CONCLUSION: In this study, PET/CT played a more important role than CE-CT scans alone and provided an impact on the management of breast cancer patients.     

Positron emission tomography/computed tomography and whole-body magnetic resonance imaging in staging of advanced nonsmall cell lung cancer--initial results

OBJECTIVE: To evaluate and compare positron emission tomography/computed tomography (PET/CT) with whole-body magnetic resonance imaging (wbMRI) in the correct staging of patients with advanced nonsmall cell lung cancer (NSCLC). MATERIALS AND METHODS: Fifty-two patients with an NSCLC stage IIIa or IIIb (36 males and 16 females) were included in this study. Patients were referred to our department for restaging. Within 1 week PET/CT and wbMRI were performed in all patients. Images were examined independently by 2 experienced physicians from the Department of Nuclear Medicine and Radiology. Afterward, consensus reading was performed. In 22 patients, surgery served as gold standard, whereas in 30 patients, follow-up controls (after 2 months) were performed. RESULTS: The use of wbMRI correctly T-staged all patients. Especially volume interpolated breathhold examination sequence correctly T-staged all tumors. PET/CT did not correctly stage chest wall infiltration in 4 cases [sensitivity 92.3% (P < 0.05 to wbMRI)/specificity 100%], verified by surgery. PET/CT correctly N-staged 51 patients (sensitivity 96.1%/specificity 100%). WbMRI showed a significant tendency to understage N-status [sensitivity 88.5% (P < 0.05)/specificity 96.1%]. Different N-status by PET/CT changed operability in 4 patients. In 2 patients, distant metastases were detected by both techniques. CONCLUSION: In the correct staging of advanced NSCLC, PET/CT has advantages in N-staging. This is of high relevance for therapy planning. WbMRI especially using volume interpolated breathhold examination sequences, has certain advantages in T-staging.     

Detection of residual tumor after radiofrequency ablation of liver metastasis with dual-modality PET/CT: initial results

The aim of this study was to determine the accuracy of dual-modality positron emission tomography(PET)/computed tomography (CT) in the detection of residual tumor after radiofrequency ablation (RFA) of liver metastasis of colorectal cancer. Eleven patients with 16 hepatic metastases (mean size 2.9 cm) from colorectal cancer were enrolled in this study, and 19 RFA procedures and 32 PET/CT examinations were performed. The patients had PET/CT before and after RFA using [¹⁸F]-2-fluoro-2-deoxy-D-glucose. CT images alone were read by two radiologists, PET images alone were evaluated by two nuclear physicians. Fused images were read by one physician of each speciality in consensus. The accuracy for detection of residual tumor by the different imaging modalities following RFA was assessed. Eleven patients with a mean age of 63 (range 55–71) years were evaluated. The mean follow-up period was 393 days. The overall procedure-based sensitivity for detection of residual tumor was 65% for PET and PET/CT and 44% for CT alone. The accuracies were 68% and 47%, respectively. Four patients had residual tumor after RFA, six patients total developed local recurrence. PET/CT therefore possibly proved superior to CT alone when assessing the liver for residual tumor after RFA.     

Cervical lymph node metastases of unknown origin: primary tumor detection with whole-body positron emission tomography/computed tomography

Background: Identification of primary tumor in patients with cervical lymph node metastasis of unknown primary (MUO) has a great impact on therapy approach and potentially on patient prognosis.

Purpose: To assess the diagnostic accuracy of combined positron emission tomography (PET)/computer tomography (CT) for primary tumor detection in cervical metastases of unknown origin compared to PET, CT, and PET+CT side-by-side evaluation.

Material and Methods: 39 consecutive patients (eight women, 31 men; mean age 59.9±11.2 years) with MUO were enrolled in this study. PET/CT images were obtained 1 hour after injection of 350 MBq of fluorodeoxyglucose. Oral and intravenous contrast agents were administered in all patients to ensure diagnostic CT data. Fused PET/CT data were evaluated for primary tumor detection. Diagnostic accuracy was calculated and compared with CT alone, PET alone, and side-by-side PET+CT evaluation. Statistical analysis of differences in diagnostic performance between the different imaging procedures was based on the McNemar test.

Results: Fused PET/CT depicted the primary tumor in 11 of 39 (28%) patients. In 28 (72%) patients, the primary tumor remained occult. CT revealed the primary in five (13%), PET alone in 10 (26%), and side-by-side evaluation of PET+CT in 10 (26%) of 39 patients. Statistical analysis showed no significant differences between the imaging modalities.

Conclusion: PET, side-by-side PET+CT, and PET/CT revealed similar detection rates for primary tumors in cervical MUO patients. Therefore, cervical metastases of an unknown primary may be assessed with either of these imaging modalities. Detection rates with CT were substantially lower. Thus, inclusion of functional data for assessment of cervical MUO patients must be recommended.     

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.     

Positron-emission tomography and computed tomography of cystic pancreatic masses

AIM: To investigate the sensitivity and specificity of computed tomography (CT), positron-emission tomography (PET), and both methods in combination, for determining whether cystic pancreatic tumours are malignant. MATERIALS AND METHODS: We retrospectively identified all patients with cystic pancreatic tumours who underwent separate PET and contrast-enhanced CT examinations within a 1-month interval. Tumours were classified as benign or malignant on CT (two radiologists, independently), PET [a reported standardized uptake value (SUV) of 2.5 was taken as the cut-off between benign and malignant], and with PET and CT images together (two radiologists, in consensus). Readers were blinded to pathological and other radiological findings. Mean patient age and lesion size were compared between benign and malignant groups using Student's t-test. For CT findings, odds ratios (OR) and confidence intervals (CI) were calculated using multivariate logistic regression models. For CT, PET, and the combined images, sensitivities and specificities were calculated, and compared between groups using Fisher's exact test. RESULTS: Thirty patients were identified. The best CT predictor of malignancy was size; mean diameter was 2.3 cm (benign) and 4.1 cm (malignant) (p<0.01); OR was 2.80 (95% CI, 1.26-6.20). Sensitivities of CT, PET and combined PET/CT images were 67-71, 57, and 86%, respectively. PET/CT was more sensitive than PET (p<0.01) or CT (p<0.01) alone. Specificities of CT, PET, and combined PET/CT images were 87-90, 65, and 91%, respectively. PET/CT was more specific than PET (p<0.01) but not CT (p>0.05). CONCLUSION: The sensitivity and specificity of combined PET and CT images is comparable with or superior to either CT or PET alone in determining malignancy in cystic pancreatic lesions.     

Comparison of FDG-PET, PET/CT and MRI for follow-up of colorectal liver metastases treated with radiofrequency ablation: initial results

PURPOSE: Morphologic imaging after radiofrequency ablation (RFA) of liver metastases is hampered by rim-like enhancement in the ablation margin, making the identification of local tumor progression (LTP) difficult. Follow-up with PET/CT is compared to follow-up with PET alone and MRI after RFA. METHODS AND MATERIALS: Sixteen patients showed 25 FDG-positive colorectal liver metastases in pre-interventional PET/CT. Post-interventional PET/CT was performed 24h after ablation and was repeated after 1, 3 and 6 months and then every 6 months. PET and PET/CT data were compared with MR data sets acquired within 14 days before or after these time points. Either histological proof by biopsy or resection, or a combination of contrast-enhanced CT at fixed time points and clinical data served as a reference. RESULTS: The 25 metastases showed a mean size of 20mm and were treated with 39 RFA sessions. Ten lesions which developed LTP received a second round of RFA; four lesions received three rounds of treatment. The mean follow-up time was 22 months. Seventy-two PET/CT and 57 MR examinations were performed for follow-up. The accuracy and sensitivity for tumor detection was 86% and 76% for PET alone, 91% and 83% for PET/CT and 92% and 75% for MRI, respectively. CONCLUSIONS: In comparison to PET alone, PET/CT was significantly better for detecting LTP after RFA. There were no significant differences between MRI and PET/CT. These preliminary results, however, need further verification.     

Staging primary head and neck cancers with <Superscript>18</Superscript>F-FDG PET/CT: is intravenous contrast administration really necessary?

Purpose  The aim of our study was to prospectively evaluate whether intravenous contrast media in integrated positron emission tomography and computed tomography (PET/CT) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) significantly contributes to evaluation of primary head and neck cancers compared with unenhanced PET/CT, regional contrast-enhanced CT of head and neck (neck CE-CT) and regional magnetic resonance imaging of head and neck (neck MRI). Methods  Subjects were 42 consecutive patients (35 men, 7 women; age range: 36–91 years) with biopsy-proven primary head and neck cancers. Lesion detection of primary and nodal sites and TNM classification were assessed on a per-patient basis. McNemar test and κ statistics were employed for statistical analyses. Results  Forty patients (95%) were successfully followed up: 24 patients had nodal disease and 3 had distant metastasis. Contrast-enhanced and unenhanced PET/CT detected 98 and 95% of the primary tumours, respectively, and both detected 92% of patients with nodal disease, which revealed no statistically significant difference. Accuracy for T status was 75 and 73%, respectively, which proved significantly more accurate than neck CE-CT, which had an accuracy of 53% (p = 0.0133 and 0.0233, respectively). Neck MRI correctly classified the T status in 58% of patients; however, no statistically significant difference was found between PET/CT and neck MRI. Contrast-enhanced PET/CT, unenhanced PET/CT, neck CT and neck MRI correctly staged the N status in 90, 90, 79 and 90% of patients, respectively, with no statistically significant difference. Overall TNM classification was correctly classified in 68 and 65% of patients, respectively. Weighted κ values between enhanced and unenhanced PET/CT for primary tumour detection, nodal detection, T status and N status were 0.655, 1.000, 0.935 and 1.000, respectively. Conclusion  We found almost perfect correlation between enhanced and unenhanced PET/CT for lesion detection and initial staging of primary head and neck cancers. Routine contrast administration for PET/CT imaging may not be justified.     

Positron emission tomography/computed tomography for staging and restaging of head and neck cancer: comparison with positron emission tomography read together with contrast-enhanced computed tomography

This retrospective study aimed to describe the differences between image readings done with combined positron emission tomography/computed tomography (PET/CT) and PET read together with contrast-enhanced CT (ceCT) in patients with squamous cell carcinoma of the head and neck. In 46 patients, no differences were found between the two readings for assessing infiltration of adjacent structures (P=.63), transgression of the midline (P=.67), lymph node involvement (P=.32), and T- and N stage. PET/CT and PET read together with ceCT have comparable diagnostic yield.     

(11)C]Choline positron emission tomography/computed tomography for staging and restaging of patients with advanced prostate cancer

INTRODUCTION: To evaluate [(11)C]Choline positron emission tomography (PET)/computed tomography (CT) for staging and restaging of patients with advanced prostate cancer and to compare the diagnostic performance of PET, CT and PET/CT. METHODS: Forty-five consecutive patients with advanced prostate cancer underwent [(11)C]Choline-PET/CT between 5/2004 and 2/2006. RESULTS: Overall, 295 lesions were detected: PET alone, 178 lesions; diagnostic CT, 221 lesions; PET/CT (low-dose CT), 272 lesions; PET/CT (diagnostic CT), 295 lesions. Two thirds of the lesions were located in the bone; one third in the prostate, lymph nodes, periprostatic tissue and soft tissue (lung, liver). The use of diagnostic CT did not result in a statistically significant difference with respect to lesion localization certainty and lesion characterization (P=.063, P=.063). PET-negative but PET/CT-positive lesions were mostly localized in the bone (78%, 91/117) as were PET-positive and CT-negative lesions (72%, 53/74). Of the latter, 91% (48/53) represented bone marrow and 9% (5/53) cortical involvement. CONCLUSIONS: Staging and restaging with [(11)C]Choline PET/CT in patients with advanced prostate cancer improve the assessment of local and regional recurrent as well as metastatic disease including skeletal manifestations. [(11)C]Choline PET/CT (with a low-dose CT) results in improved localization and lesion characterization. [(11)C]Choline PET/CT provides an added value for skeletal manifestations. [(11)C]Choline PET/CT changed disease management in 11 (24%) of 45 patients with advanced prostate cancer.     

F-18]fluorodeoxyglucose positron emission tomography and positron emission tomography: computed tomography in recurrent and metastatic cholangiocarcinoma

OBJECTIVES: We retrospectively assessed the diagnostic utility of dedicated positron emission tomography (PET) and hybrid PET-computed tomography (CT) scans with [F-18]fluorodeoxyglucose (FDG) in the imaging evaluation of patients with known or suspected recurrent and metastatic cholangiocarcinoma. METHODS: The study group included 24 patients (13 males and 11 females; age range, 34-75 years) with known or suspected recurrent and metastatic cholangiocarcinoma. We performed 8 dedicated PET scans (Siemens 953/A, Knoxville, Tenn) in 8 patients and 24 hybrid PET-CT scans (Siemens Biograph, Knoxville, Tenn) in 16 patients. Four patients underwent both pretreatment and posttreatment scans. Nonenhanced CT transmission scans were obtained for attenuation correction after administration of oral contrast material. PET images were obtained 60 minutes after the intravenous administration of 15 mCi (555 MBq) FDG. Prior treatments included surgery alone in 12 patients, surgery and chemotherapy in 6 patients, and surgery and combined chemoradiation therapy in 6 patients. Diagnostic validation was conducted through clinical and radiologic follow-up (2 months to 8 years). RESULTS: PET and CT were concordant in 18 patients. PET-CT correctly localized a hypermetabolic metastatic lesion in the anterior subdiaphragmatic fat instead of within the liver and was falsely negative in intrahepatic infiltrating type cholangiocarcinoma. PET was discordant with CT in 6 patients. PET was negative in an enlarged right cardiophrenic lymph node on CT, which remained stable for 1 year. In 1 patient, PET-CT scan showed hypermetabolic peritoneal disease in the right paracolic gutter without definite corresponding structural abnormalities, which was subsequently confirmed on a follow-up PET-CT scan performed 6 months after the initial study, at which time peritoneal nodular thickening was evident on concurrent CT. PET-CT documented the progression of locally recurrent and metastatic disease in another patient based on interval appearance of several new hypermetabolic lesions and significant increase in the standardized uptake values of the known lesions despite little interval change in the size and morphologic character of lesions on concurrent CT. It was also helpful in excluding metabolically active disease in patients with contrast enhancement at either surgical margin of hepatic resection site or focally within hepatic parenchyma and in an osseous lesion. Overall, based on the clinically relevant patient basis for detection of recurrent and metastatic cholangiocarcinoma, the sensitivity and specificity of PET (alone and combined with CT) were 94% and 100% and, for CT alone, were 82% and 43%, respectively. CONCLUSIONS: FDG PET and PET-CT are useful in the imaging evaluation of patients with cholangiocarcinoma (except for infiltrating type) for detection of recurrent and metastatic disease and for assessment of treatment response. In particular, the combined structural and metabolic information of PET-CT enhances the diagnostic confidence in lesion characterization.     

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     

F-18-fluoro-2-deoxyglucose positron emission tomography/computed tomography in the follow-up of breast cancer with elevated levels of tumor markers

OBJECTIVE: The value of combined positron emission tomography (PET)/computed tomography (CT) in the follow-up of patients with breast cancer with elevated tumor markers but without proven metastases or local recurrence was assessed. METHODS: Thirty-four women underwent PET/CT. The PET and CT images were first analyzed separately; fused findings were then interpreted, blinded to the results of the other modalities. The results of CT, PET, and PET/CT were compared with each other and correlated to the final diagnosis. RESULTS: The PET/CT identified 149 malignant foci in 24 patients (71%). The CT detected 96 of these foci in 18 patients, whereas PET identified 124 foci in 17 patients. Differences between CT and PET were not significant. Differences between PET/CT and CT (P < 0.01) and PET/CT and PET (P < 0.01) were significant. The person-based sensitivity of PET/CT, PET, and CT was 96%, 88% and 96%, respectively. Specificity of PET/CT, PET, and CT was 89%, 78%, and 78%, respectively. CONCLUSIONS: The PET/CT is a valuable modality for the follow-up of patients with breast cancer and elevated levels of tumor markers.     

FDG-PET/CT in restaging of patients with recurrent breast cancer: possible impact on staging and therapy

We aimed to compare the value of combined positron emission tomography (PET)/CT, PET+CT (viewed side by side), CT alone and PET alone concerning the rTNM stage and influence on therapy in patients with recurrent breast cancer. 44 patients with suspicion of recurrent breast cancer underwent whole-body [18F]-2-fluoro-2-deoxy-d-glucose (FDG)-PET/CT. Images of combined PET/CT, PET+CT, PET alone and CT alone were evaluated by four blinded reader teams. Diagnostic accuracies and influence on therapy were compared. Histology and a mean clinical follow up of 456 days served as the standard of reference. Differences between the staging procedures were tested for statistical significance by McNemar's test. Overall TNM tumour stage was correctly determined in 40/44 patients with PET/CT, in 38/44 with PET+CT, in 36/44 with PET alone and in 36/44 patients with CT alone. No statistically significant difference was detected between all tested imaging modalities. PET/CT changed the therapy in two patients compared with PET+CT, in four patients compared with PET alone and in five patients compared with CT alone. Combined PET/CT appeared to be more accurate in assessing the rTNM and showed a moderate impact on therapy over PET and CT. Minor improvements were noted when compared with PET+CT. Experienced readers might therefore be able to provide accurate staging results for further therapy from separately acquired studies.     

Non-small cell lung cancer: dual-modality PET/CT in preoperative staging

PURPOSE: To determine the accuracy of dual-modality positron emission tomographic (PET)-computed tomographic (CT) imaging, as compared with PET alone and CT alone, in the staging of non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Twenty-seven patients with NSCLC underwent staging with combined fluorine 18 fluorodeoxyglucose PET and CT. CT, PET, and coregistered PET/CT images were evaluated separately by two different physicians for each imaging modality, and disease stage was determined by using TNM and American Joint Committee on Cancer staging systems. Histopathologic results served as the reference standard. The statistical significance of differences among CT, PET, and PET/CT was determined by using the McNemar test. RESULTS: Overall tumor stage was correctly classified as 0-IV with CT in 19 patients, with PET in 20 patients, and with PET/CT in 26 patients. PET/CT findings when compared with PET findings led to a treatment change for four patients (15%) and when compared with CT findings led to a treatment change for five patients (19%). Differences in the accuracy of overall tumor staging between PET/CT and CT (P =.008) and between PET/CT and PET (P =.031) were significant. Primary tumor stage was correctly determined in more patients with PET/CT than with either PET alone or CT alone. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of regional lymph node staging, respectively, were 89%, 94%, 89%, 94%, and 93%, with PET/CT; 89%, 89%, 80%, 94%, and 89% with PET; and 70%, 59%, 50%, 77%, and 63% with CT. Fourteen distant metastases were detected in four patients with CT, four were detected in two patients with PET, and 17 were detected in four patients with PET/CT. CONCLUSION: Use of dual-modality PET/CT significantly increases the number of patients with correctly staged NSCLC and thus has a positive effect on treatment.     

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.     

Whole-body positron emission tomography using fluorodeoxyglucose for staging of lymphoma: effectiveness and comparison with computed tomography

The purpose of this study was to evaluate whole-body positron emission tomography (WB-PET) as a staging modality in Hodgkin’s disease (HD) and non-Hodgkin lymphoma (NHL) and to compare it with computed tomography (CT) in a retrospective study. Seventy-one WB-PET studies using fluorodeoxyglucose (FDG) and 49 CT examinations were performed in 19 women and 31 men. Transaxial images were acquired and reformatted coronally and sagittally in PET. CT sections were obtained from the skull base to the pelvic floor. The written reports of the imaging data were compared with a reference standard constructed on the basis of all the data on the individual patients, including clinical follow-up of at least 6 months. The sensitivity and specificity of PET were, respectively, 86% and 96% for HD (n=53), and 89% and 100% for NHL (n=18). For CT sensitivity and specificity were 81% and 41% for HD (n=33) and 86% and 67% for NHL (n=16). Differences between PET and CT sensitivities were not significant, while in HD there was a significant difference in the specificity of PET and CT examinations, mainly because CT was unable to distinguish between active or recurrent disease and residual scar tissue after therapy. FDG tumour uptake was found in high- as well as low-grade NHL patients. In conclusion, PET appears to be highly sensitive and specific for staging of lymphoma. It is at least as sensitive as CT, and more specific, particularly in patients undergoing restaging, where a well-recognized diagnostic dilemma in CT is the presence of a post-therapeutic residual mass. Received 5 January and in revised form 10 March 1998     

Primary staging of lymphomas: cost-effectiveness of FDG-PET versus computed tomography

The objective of this study was to measure the incremental cost-effectiveness of 2-(fluorine-18) fluorodeoxyglucose positron emission tomography (FDG-PET) versus computed tomography (CT) as diagnostic procedures in the primary staging of malignant lymphomas. The study was based on 22 patients of a clinical study who underwent the diagnostic procedures at Ulm University Hospital between April 1997 and May 1998. Direct costs of FDG-PET and CT, including staff, materials, investment, maintenance and overheads, were valued using a micro-costing approach. The effectiveness of both diagnostic procedures was measured as the percentage of correctly staged patients, given a gold standard for staging. The incremental cost-effectiveness ratio was the main outcome measure. Costs per patient of FDG-PET were 257 euros for FDG production and 704 euros for the FGD-PET scan, thus totalling 961 euros (in 1999 prices). The cost per patient of CT scans was found to be 391 euros. Verified PET findings induced an upstaging in four patients such that the effectiveness was 81.8% (18/22) for CT and 100% (22/22) for PET. Incremental cost-effectiveness ratios (interpreted as the additional costs of a more effective diagnostic strategy per additional unit of effectiveness, i.e. additionally correctly staged patient, achieved) were 478 euros per correctly staged patient for CT versus "no diagnostics" and 3133 euros for FDG-PET versus CT. Great potential for cost saving was identified in sensitivity analyses for FDG-PET. It is concluded that diagnostic accuracy and the costs of the diagnostic procedures could be measured precisely. FDG-PET was more accurate than CT. Decision-makers who consider savings in treatment costs significant may find the cost-effectiveness ratio of PET to lie within an acceptable range. However, more research is needed to assess the long-term treatment and cost effects of more accurate staging. There is significant potential to improve the technical efficiency of PET.     

Primary staging of lymphomas: cost-effectiveness of FDG-PET versus computed tomography

The objective of this study was to measure the incremental cost-effectiveness of 2-(fluorine-18) fluorodeoxyglucose positron emission tomography (FDG-PET) versus computed tomography (CT) as diagnostic procedures in the primary staging of malignant lymphomas. The study was based on 22 patients of a clinical study who underwent the diagnostic procedures at Ulm University Hospital between April 1997 and May 1998. Direct costs of FDG-PET and CT, including staff, materials, investment, maintenance and overheads, were valued using a micro-costing approach. The effectiveness of both diagnostic procedures was measured as the percentage of correctly staged patients, given a gold standard for staging. The incremental cost-effectiveness ratio was the main outcome measure. Costs per patient of FDG-PET were 257 euros for FDG production and 704 euros for the FGD-PET scan, thus totalling 961 euros (in 1999 prices). The cost per patient of CT scans was found to be 391 euros. Verified PET findings induced an upstaging in four patients such that the effectiveness was 81.8% (18/22) for CT and 100% (22/22) for PET. Incremental cost-effectiveness ratios (interpreted as the additional costs of a more effective diagnostic strategy per additional unit of effectiveness, i.e. additionally correctly staged patient, achieved) were 478 euros per correctly staged patient for CT versus "no diagnostics" and 3133 euros for FDG-PET versus CT. Great potential for cost saving was identified in sensitivity analyses for FDG-PET. It is concluded that diagnostic accuracy and the costs of the diagnostic procedures could be measured precisely. FDG-PET was more accurate than CT. Decision-makers who consider savings in treatment costs significant may find the cost-effectiveness ratio of PET to lie within an acceptable range. However, more research is needed to assess the long-term treatment and cost effects of more accurate staging. There is significant potential to improve the technical efficiency of PET.     

Integrated PET/CT in the preoperative staging of lung cancer: A prospective comparison of CT,PET and integrated PET/CT

Purpose

The purpose of this study was to evaluate the role of integrated PET/CT in the staging of lung cancer compared with CT alone or PET alone.

Materials and methods

Thirty-three patients underwent integrated PET/CT for the staging of lung cancer. The tumor, node and metastasis (TNM) stages were assessed with CT, PET and integrated PET–CT and compared with the surgical and pathological staging.

Results

CT correctly evaluated the (T) status in (64%) of the patients, PET in (59%) and PET/CT in (86%). CT correctly evaluated the (N) status in (73%) of the patients, PET in (76%), and PET/CT (88%) with accuracy, sensitivity, specificity, PPV and NPV were 73%, 78%, 71%, 50% and 94% for CT, 76%, 67%, 79%, 55% and 95% for PET and 88%, 89%, 88%, 73% and 100% for PET/CT respectively, and for (M) status were 91%, 86%, 92%, 75% and 96% for CT, 88%, 71%, 92%, 71% and 92% for PET and 97%, 100%, 96%, 88% and 100% for PET/CT respectively. Regarding the overall TNM staging CT correctly staged 24 patients. PET correctly staged 23 cases while PET/CT correctly staged 30 cases. A significant difference in the accuracy of overall tumor staging between PET/CT and CT (P = 0.0412) or PET (P = 0.0233).

Conclusion

The integrated PET/CT is superior to either CT or PET in the staging of lung cancer which has an important impact on selection of the appropriate treatment regimen.