The value of PET/CT for preoperative staging of advanced gastric cancer: Comparison with contrast-enhanced CT

Aim

To date, no data are available on the use of PET/CT for preoperative staging of gastric cancer. We attempted to evaluate the value of PET/CT for preoperative staging of advanced gastric cancer, and to compare the use of PET/CT with contrast-enhanced CT (CECT).

Materials and methods

We analyzed PET/CT of 78 patients with surgically proven advanced gastric cancer who had undergone preoperative CECT. Qualitative analysis was conducted by assessing the presence of primary tumors and metastases with PET/CT and CECT.

Results

Among 71 patients who underwent a gastrectomy, 69 primary tumors (93%) were diagnosed by PET/CT, while 64 primary tumors (90%) were detected by CECT (p = 0.55). For regional lymph node metastasis, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of PET/CT vs. CECT were 41% vs. 25% (p = 0.00019), 100% vs. 92% (p = 0.31), 100% vs. 98% (p = 0.46), 26% vs. 42% (p = 0.14), and 51% vs. 72% (p = 0.00089), respectively.

Conclusion

Overall, PET/CT showed comparable diagnostic performance to CECT in diagnosing primary tumors and regional lymph node metastases, though PET/CT was inferior to CECT for the sensitivity and accuracy in diagnosing regional lymph node metastases. Nevertheless, PET/CT would be useful when CECT findings were equivocal due to its high positive predictability.     

Depiction and characterization of liver lesions in whole body [F]-FDG PET/MRI

Objectives

To assess the value of PET/MRI with [¹⁸F]-FDG using a whole body protocol for the depiction and characterization of liver lesions in comparison to PET/CT.

Methods

70 patients (31 women, 39 men) with solid tumors underwent [¹⁸F]-FDG PET/CT and followed by an additional PET/MRI using an integrated scanner. Two readers rated the datasets (PET/CT; PET/MRI) regarding conspicuity of hepatic lesions (4-point ordinal scale) and diagnostic confidence (5-point ordinal scale). Median scores for lesion conspicuity and diagnostic confidence were compared using Wilcoxon's rank sum test. Prior examinations, histopathology and clinical follow-up (116 ± 54 days) served as standard of reference.

Results

36 of 70 (51%) patients showed liver lesions. Using PET/CT and PET/MRI all patients with liver metastases could correctly be identified. A total of 97 lesions were found (malignant n = 26; benign n = 71). For lesion conspicuity significantly higher scores were obtained for PET/MRI in comparison to PET/CT (p < 0.001). Significantly better performance for diagnostic confidence was observed in PET/MRI, both for malignant as for benign lesions (p < 0.001).

Conclusions

PET/MRI, even in the setting of a whole body approach, provides higher lesion conspicuity and diagnostic confidence compared to PET/CT and may therefore evolve as an attractive alternative in oncologic imaging.     

Does the pretreatment tumor sampling location correspond with metabolic activity on 18F-FDG PET/CT in breast cancer patients scheduled for neoadjuvant chemotherapy?

Purpose

To define the correlation between the core biopsy location and the area with highest metabolic activity on 18F-FDG PET/CT in stage II–III breast cancer patients before neoadjuvant chemotherapy. Also, we would like to select a subgroup of patients in which PET/CT information may optimize tumor sampling.

Methods

A PET/CT in prone position was acquired in 199 patients with 203 tumors. The distance and relative difference in standardized uptake value (SUV) between core biopsy localization (indicated by a marker) and area with highest degree of FDG uptake were evaluated. A distance ≥2 cm and a relative difference in SUV ≥25% were considered clinically relevant and a combination of both was defined as non-correspondence. Non-correspondence for different tumor characteristics (TNM stage, lesion morphology on MRI and PET/CT, histology, subtype, grade, and Ki-67) was assessed.

Results

Non-correspondence was found in 28 (14%) of 203 tumors. Non-correspondence was significantly associated with T-stage, lesion morphology on MRI and PET/CT, tumor diameter, and histologic type. It was more often seen in tumors with a higher T-stage (p = 0.028), diffuse (non-mass) and multifocal tumors on MRI (p = 0.001), diffuse and multifocal tumors on PET/CT (p < 0.001), tumors >3 cm (p < 0.001), and lobular carcinomas (p < 0.001). No association was found with other features.

Conclusion

Non-correspondence between the core biopsy location and area with highest FDG uptake is regularly seen in stage II–III breast cancer patients. PET/CT information and possibly FDG-guided biopsies are most likely to improve pretreatment tumor sampling in tumors >3 cm, lobular carcinomas, and diffuse and multifocal tumors.     

Value of retrospective image fusion of F-FDG PET and MRI for preoperative staging of head and neck cancer: Comparison with PET/CT and contrast-enhanced neck MRI

Purpose

To assess the clinical value of retrospective image fusion of neck MRI and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET for locoregional extension and nodal staging of neck cancer.

Materials and methods

Thirty patients with carcinoma of the oral cavity or hypopharynx underwent PET/CT and contrast-enhanced neck MRI for initial staging before surgery including primary tumor resection and neck dissection. Diagnostic performance of PET/CT, MRI, and retrospective image fusion of PET and MRI (fused PET/MRI) for assessment of the extent of the primary tumor (T stage) and metastasis to regional lymph nodes (N stage) was evaluated.

Results

Accuracy for T status was 87% for fused PET/MRI and 90% for MRI, thus proving significantly superior to PET/CT, which had an accuracy of 67% (p = 0.041 and p = 0.023, respectively). Accuracy for N status was 77% for both fused PET/MRI and PET/CT, being superior to MRI, which had an accuracy of 63%, although the difference was not significant (p = 0.13). On a per-level basis, the sensitivity, specificity and accuracy for detection of nodal metastasis were 77%, 96% and 93% for both fused PET/MRI and PET/CT, compared with 49%, 99% and 91% for MRI, respectively. The differences for sensitivity (p = 0.0026) and accuracy (p = 0.041) were significant.

Conclusion

Fused PET/MRI combining the individual advantages of MRI and PET is a valuable technique for assessment of staging neck cancer.     

Comparison of whole-body PET/CT and PET/MRI in breast cancer patients: Lesion detection and quantitation of 18F-deoxyglucose uptake in lesions and in normal organ tissues

Purpose

To compare the performance of PET/MRI imaging using MR attenuation correction (MRAC) (DIXON-based 4-segment -map) in breast cancer patients with that of PET/CT using CT-based attenuation correction and to compare the quantification accuracy in lesions and in normal organ tissues.

Methods

A total of 36 patients underwent a whole-body PET/CT scan 1 h after injection and an average of 62 min later a second scan using a hybrid PET/MRI system. PET/MRI and PET/CT were compared visually by rating anatomic allocation and image contrast. Regional tracer uptake in lesions was quantified using volumes of interest, and maximal and mean standardized uptake values (SUVmax and SUVmean, respectively) were calculated. Metabolic tumor volume (MTV) of each lesion was computed on PET/MRI and PET/CT. Tracer uptake in normal organ tissue was assessed as SUVmax and SUVmean in liver, spleen, left ventricular myocardium, lung, and muscle.

Results

Overall 74 FDG positive lesions were visualized by both PET/CT and PET/MRI. No significant differences in anatomic allocation scores were found between PET/CT and PERT/MRI, while contrast score of lesions on PET/MRI was significantly higher. Both SUVmax and SUVmean of lesions were significantly higher on PET/MRI than on PET/CT, with strong correlations between PET/MRI and PET/CT data (ρ = 0.71–0.88). MTVs of all lesions were 4% lower on PET/MRI than on PET/CT, but no statistically significant difference was observed, and an excellent correlation between measurements of MTV with PET/MRI and PET/CT was found (ρ = 0.95–0.97; p < 0.0001). Both SUVmax and SUVmean were significantly lower by PET/MRI than by PET/CT for lung, liver and muscle, no significant difference was observed for spleen, while either SUVmax and SUVmean of myocardium were significantly higher by PET/MRI. High correlations were found between PET/MRI and PET/CT for both SUVmax and SUVmean of the left ventricular myocardium (ρ = 0.91; p < 0.0001), while moderate correlations were found for the other normal organ tissues (ρ = 0.36–0.61; p < 0.05).

Conclusions

PET/MRI showed equivalent performance in terms of qualitative lesion detection to PET/CT. Despite significant differences in tracer uptake quantification, due to either methodological and biological factors, PET/MRI and PET/CT measurements in lesions and normal organ tissues correlated well. This study demonstrates that integrated whole-body PET/MRI is feasible in a clinical setting with high quality and in a short examination time.     

The value of gamma camera and computed tomography data set coregistration to assess Lewis Y antigen targeting in small cell lung cancer by Indium-labeled humanized monoclonal antibody 3S193

Aim

To assess the value of data set coregistration of gamma camera and computed tomography (CT) in the assessment of targeting of humanized monoclonal antibody 3S193 labeled with indium-111 (¹¹¹In-hu3S193) to small cell lung cancer (SCLC).

Methods and materials

Ten patients (6 male and 4 female; mean age ± S.D., 60 ± 4 years), from an overall population of 20 patients with SCLCs expressing Lewis Y antigen at immunohistochemical analysis, completed a four weekly injections of ¹¹¹In-hu3S193 and underwent gamma camera imaging. All had had, as part of their baseline evaluation, Fluorine18 fluoro-2-deoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). Two readers in consensus retrospectively coregistered the gamma camera images with the CT component of the FDG PET/CT by automatic or manual alignment. The resulting image sets were visually examined and SCLC lesions targeting at coregistered gamma camera and CT was correlated side-by-side with the ¹⁸F-FDG uptake.

Results

A total number of 31 lesions from SCLC with a thoracic (n = 13) or extrathoracic location (n = 18) were all positive on FDG PET/CT. Coregistration of the gamma camera to the CT demonstrated targeting of antibody to all lesions >2 cm (n = 20) and in a few lesions ≤2 cm (n = 2), with no visualization of most lesions ≤2 cm (n = 9). No ¹¹¹In-hu3S193 uptake in normal tissues was observed.

Conclusion

Coregistration of antibody gamma camera imaging to FDG PET/CT is feasible and allows valuable assessment of ¹¹¹In-hu3S193 antibody targeting to SCLC lesions >2 cm, while lesions ≤2 cm reveal a limited targeting.     

Role of respiratory-gated PET/CT for pancreatic tumors: A preliminary result

Purpose

The aim of this study is to ascertain role of respiratory-gated PET/CT for accurate diagnosis of pancreatic tumors.

Materials and methods

Prior to clinical study, the phantom study was performed to evaluate the impact of respiratory motion on lesion quantification. Twenty-two patients (mean age 65 years) with pancreatic tumors were enrolled. Pathological diagnoses by surgical specimens consisted of pancreatic cancer (n = 15) and benign intraductal papillary mucinous neoplasm (IPMN, n = 7). Whole-body scan of non-respiratory-gated PET/CT was performed at first, and subsequent respiratory-gated PET/CT for one bed position was performed. All PET/CT studies were performed prior to surgery. The SUV max obtained by non-respiratory-gated PET/CT and respiratory-gated PET/CT, and percent difference in SUVmax (%SUVmax) were compared.

Results

The profile curve of 5 respiratory bin image was most similar to that of static image. The third bin of 5 respiratory bin image showed highest FWHM (24.0 mm) and FWTM (32.7 mm). The mean SUVmax of pancreatic cancer was similar to that of benign IPMN on non-respiratory-gated PET/CT (p = 0.05), whereas significant difference was found between two groups on respiratory-gated PET/CT (p = 0.016). The mean %SUV of pancreatic cancer was greater than that of benign IPMN (p < 0.0001). Identification of the primary tumor in pancreatic head (n = 13, 59%) was improved by using respiratory-gated PET/CT because of minimal affection of physiological accumulation in duodenum.

Conclusion

Respiratory-gated PET/CT is a feasible technique for evaluation of pancreatic tumors and allows more accurate identification of pancreatic tumors compared with non-respiratory-gated PET/CT.     

A study of plaque vascularization and inflammation using quantitative contrast-enhanced US and PET/CT

Background

Contrast-enhanced ultrasound (CEUS) is an in vivo methodology to quantify carotid plaque vascularization. Increased metabolism in plaques, measured as FDG uptake in PET/CT examination, has been associated with markers of inflammation in histological samples. In this study, we tested the association between FDG uptake and vascularization measured by CEUS to assess whether CEUS can be used as an in vivo marker of plaque vulnerability.

Methods

After informed consent, subjects aged >60 years with carotid plaque height exceeding 2.5 mm were recruited. CEUS was performed and analyzed using earlier described protocol and software, Contrast Quantification Program, which calculates the fraction of the plaque being contrast positive (CQP value). PET/CT examination was performed within 3 months of CEUS (median time 7 days). PET/CT images were acquired 90 min after FDG injection (2.7 MBq/kg). FDG uptake was measured as tissue background index (TBI), calculated using Spearman's rho as mean standard uptake value (SUV) of the plaque divided by mean SUV in the jugular vein (mean of 7 measuring points). Local ethics committee approved the study.

Results

We recruited 13 subjects (5 women) with a mean age of 71 years, 6 had a history of stroke or TIA, 1 had a history of ipsilateral stroke. CQP values showed a significant, positive correlation with TBI of carotid plaques, r = 0.67, p < 0.02.

Conclusions

Plaque vascularization measured by CEUS correlates positively with FDG uptake measured by PET/CT in humans. This indicates an association between vascularization and inflammation and/or hypoxia, supporting the use of CEUS as a non-invasive method to detect plaque vulnerability.     

The clinical utility of FDG-PET/CT in follow up and restaging of breast cancer patients

Background

Early diagnosis and accurate staging of loco-regional and distant recurrence after treatment of breast cancer is decisive for further therapeutic planning. Our aim was to evaluate the role of FDG-PET/CT in the follow up and restaging of breast cancer patients.

Methods

We retrospectively evaluated 34 female patients with a history of breast cancer. Patients were referred for a PET/CT scan because of suspected recurrence (n = 15), whole body staging in already confirmed cases of recurrence (n = 5), follow up and reassurance in asymptomatic patients (n = 7), follow up after local ablative therapy of liver metastases (n = 5), follow up after treatment of bone metastases (n = 2). PET-CT findings were compared with the findings obtained by other imaging modalities, histopathology, together with clinical and imaging follow up for at least 6 months.

Results

The PET/CT was considered pathological in 21/34 patients. Incorrect interpretations of PET/CT images occurred in 3 patients (8.8%). PET/CT showed an overall diagnostic accuracy of 91.2% with a sensitivity of 90.5% and a specificity of 92.3%. The PPV and NPV were 95% and 85.7%, respectively.

Conclusion

FDG-PET/CT may play a substantial role in the restaging and follow up of patients with breast cancer showing high sensitivity and specificity.     

Value of F-FDG PET/CT in the diagnosis of primary gastric cancer via stomach distension

Objective

To clarify the usefulness of ¹⁸F-FDG PET/CT for detecting primary gastric cancer via gastric distention using a mixture of milk and Diatrizoate Meglumine.

Materials and methods

A total of 68 patients (male: 47, female: 21; age: 41–87 years) suspected of gastric carcinoma underwent ¹⁸F-FDG PET/CT imaging. After whole-body PET/CT imaging in a fasting state, the patients drank a measured amount of milk with Diatrizoate Meglumine. Local gastric district PET/CT imaging was performed 30 min later. The imaging was analyzed by semi-quantitative analysis, standardized uptake value (SUV) of the primary tumor was measured in a region of interest. The diagnosis results were confirmed by gastroscopy, pathology, and follow-up results.

Results

Of the 68 patients, 56 malignant gastric neoplasm patients (male: 37, female: 19) were conformed. The sensitivity, specificity, positive predictive value and negative predictive value of fasting whole-body PET/CT imaging for a primary malignant tumor were 92.9%, 75.0%, 94.5%, and 69.0%, respectively. The values for distension with a mixture of milk and Diatrizoate Meglumine were 91.1%, 91.7%, 98.1%, and 68.8%, respectively. The area under the curve was 0.919 ± 0.033 and 0.883 ± 0.066 for the diagnosis of gastric cancer with SUV_max in a fasting state and after intake of mixture respectively, the differences were not statistically significant (P = 0.359). Using gastric distension with a mixture of milk and Diatrizoate Meglumine, the mean ratio of the lesion's SUV_max to the adjacent gastric wall SUV_max increased significantly from 3.30 ± 3.05 to 13.50 ± 15.05, which was statistically significant (P < 0.001).

Conclusions

¹⁸F-FDG PET/CT imaging is highly accurate for the diagnosis of primary gastric carcinoma. Gastric distention can display the lesions more clearly, however, it cannot significantly improve diagnostic accuracy.     

Body surface area adapted iopromide 300 mg/ml versus 370 mg/ml contrast medium injection protocol: Influence on quantitative and clinical assessment in combined PET/CT

Purpose

To investigate the quantitative and qualitative differences between combined positron emission tomography and computed X-ray tomography (PET/CT) enhanced with contrast medium with either an iodine concentration 300 mg/ml or 370 mg/ml.

Materials and methods

120 consecutive patients scheduled for F-18-Fluorodeoxyglucose (FDG) PET/CT were included. The first (second) 60 patients received contrast medium with 300 (370) mg iodine/ml. Intravenous injection protocols were adapted for an identical iodine delivery rate (1.3 mg/s) and body surface area (BSA) adapted iodine dose (22.26 g I/m²). Maximum and mean standardized uptake values (SUV_max; SUV_mean) and contrast enhancement (HU) were determined in the ascending aorta, the abdominal aorta, the inferior vena cava, the portal vein, the liver and the right kidney in the venous contrast medium phase. PET data were evaluated visually for the presence of malignancy and image quality.

Results

Both media caused significantly higher values for HU, SUV_mean and SUV_max for the enhanced PET/CT than the non-enhanced one (all p < 0.01). There were no significant differences in the degree of increase of HU, SUV_mean and SUV_max between the two contrast media at any anatomic site (all p > 0.05). Visual evaluation of lesions showed no differences between contrast and non-contrast PET/CT or between the two different contrast media (p = 0.77).

Conclusion

When using a constant iodine delivery rate and total iodine dose in a BSA adapted injection protocol, there are no quantitative or qualitative differences in either CT or PET between contrast media with an iodine concentration of 300 mg/ml and 370 mg/ml, respectively.     

FDG uptake heterogeneity evaluated by fractal analysis improves the differential diagnosis of pulmonary nodules

Purpose

The present study aimed to determine whether fractal analysis of morphological complexity and intratumoral heterogeneity of FDG uptake can help to differentiate malignant from benign pulmonary nodules.

Materials and methods

We retrospectively analyzed data from 54 patients with suspected non-small cell lung cancer (NSCLC) who were examined by FDG PET/CT. Pathological assessments of biopsy specimens confirmed 35 and 19 nodules as NSCLC and inflammatory lesions, respectively. The morphological fractal dimension (m-FD), maximum standardized uptake value (SUV_max) and density fractal dimension (d-FD) of target nodules were calculated from CT and PET images. Fractal dimension is a quantitative index of morphological complexity and tracer uptake heterogeneity; higher values indicate increased complexity and heterogeneity.

Results

The m-FD, SUV_max and d-FD significantly differed between malignant and benign pulmonary nodules (p < 0.05). Although the diagnostic ability was better for d-FD than m-FD and SUV_max, the difference did not reach statistical significance. Tumor size correlated significantly with SUV_max (r = 0.51, p < 0.05), but not with either m-FD or d-FD. Furthermore, m-FD combined with either SUV_max or d-FD improved diagnostic accuracy to 92.6% and 94.4%, respectively.

Conclusion

The d-FD of intratumoral heterogeneity of FDG uptake can help to differentially diagnose malignant and benign pulmonary nodules. The SUV_max and d-FD obtained from FDG-PET images provide different types of information that are equally useful for differential diagnoses. Furthermore, the morphological complexity determined by CT combined with heterogeneous FDG uptake determined by PET improved diagnostic accuracy.     

Staging accuracy of pancreatic cancer: Comparison between non-contrast-enhanced and contrast-enhanced PET/CT

Purpose

Our aim was to clarify the diagnostic impact of contrast-enhanced (CE) ¹⁸F-fluorodeoxyglucose (FDG)–positron emission tomography (PET)/computed tomography (CT) for staging of pancreatic cancer compared to non-CE PET/CT.

Method and materials

Between April 2006 and November 2009, a total of 95 patients (age range, 36–83 years [mean age, 67]) with primary pancreatic cancer underwent ¹⁸F-FDG PET/CT examinations. Diagnostic accuracy was compared between non-CE PET/CT and CE PET/CT. Images were analyzed visually and quantitatively by two blinded reviewers. Reference standard was histological examination in 48 patients (51%) and/or confirmation of an obvious progression in number and/or size of the lesions on follow-up CT examinations in 47 patients (49%).

Results

For T-staging, invasion of duodenum (n = 20, 21%), mesentery (n = 12, 13%), and retroperitoneum (n = 13, 14%) was correctly diagnosed by both modalities. The ROC analyses revealed that the Az values of celiac artery (CA), common hepatic artery (CHA), splenic artery (SV), and superior mesenteric vein (SMV) invasion were significantly higher in the CE PET/CT group for both readers. Nodal metastasis was correctly diagnosed by CE PET/CT in 38 patients (88%) and by non-CE PET/CT in 45 patients (87%). Diagnostic accuracies of nodal metastasis in two modalities were similar. Using CE PET/CT, distant metastasis, scalene node metastasis, and peritoneal dissemination were correctly assigned in 39 patients (91%), while interpretation based on non-CE PET/CT revealed distant metastasis, scalene node metastasis, and peritoneal dissemination in 42 patients (81%). Diagnostic accuracy of distant metastasis, scalene node metastasis, and peritoneal dissemination with CE PET/CT was significantly higher than that of non-CE PET/CT (p < 0.05).

Conclusion

CE PET/CT allows a more precise assessment of distant metastasis, scalene node metastasis, and peritoneal dissemination in patients with pancreatic cancer.     

Potential impact of PET/CT on the initial staging of lymphoma

Purpose

The aim of this study was to investigate the potential impact of PET/CT on the initial staging of lymphoma with comparison to each of the PET and CT components alone.

Materials and methods

PET/CTs from 37 patients with lymphoma undergoing initial staging were studied. Review of PET, CT and PET/CT images were done and staging of each patient by each modality was assigned and compared together. Clinical follow-up, additional imaging and histology served as the standard of reference.

Results

PET/CT correctly diagnosed 83 nodal regions as positive for lymphomatous involvement versus 61 and 57 detected by PET and CT respectively. The respective sensitivities, specificities, and accuracies for the detection of nodal involvement were: PET: 88.4%, 65%, 94%, CT 89.1%, 60.1%, 96.1%, PET/CT 96.3%, 88.3%, 98.2%. PET/CT also correctly identified more extra-nodal lesions (n = 24) than CT (n = 16) and PET (n = 15). Correct staging was more accurate at PET/CT (n = 31) in comparison to PET alone (n = 23) and CT alone (n = 21).

Conclusions

PET/CT was superior to PET and CT in the initial staging of lymphoma with significant better performance compared to PET and CT to clarify nodal and extra-nodal involved sites. The application of PET/CT rather than CT or PET is likely to be more beneficial.     

Standardized uptake values for [F] FDG in normal organ tissues: Comparison of whole-body PET/CT and PET/MRI

Purpose

To compare maximum and mean standardized uptake values (SUVmax/mean) of normal organ tissues derived from [¹⁸F]-fluoro-desoxyglucose (FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) using MR attenuation correction (MRAC) (DIXON-based 4-segment μ-map) with [¹⁸F]-FDG positron emission tomography/computed tomography (PET/CT) using CT-based attenuation correction (CTAC).

Methods and materials

In 25 oncologic patients (15 men, 10 women; age 57 ± 13 years) after routine whole-body FDG-PET/CT (60 min after injection of 290 ± 40 MBq [¹⁸F]-FDG) a whole-body PET/MRI was performed (Magnetom Biograph mMR™, Siemens Healthcare, Erlangen, Germany). Volumes of interest of 1.0 cm³ were drawn in 7 physiological organ sites in MRAC-PET and the corresponding CTAC-PET images manually. Spearman correlation coefficients were calculated to compare MRAC- and CTAC based SUV values; Wilcoxon-Matched-Pairs signed ranks test was performed to test for potential differences.

Results

The mean delay between FDG-PET/CT and PET/MRI was 92 ± 18 min. Excellent correlations of SUV values were found for the heart muscle (SUVmax/mean: R = 0.97/0.97); reasonably good correlations were found for the liver (R = 0.65/0.72), bone marrow (R = 0.42/0.41) and the SUVmax of the psoas muscle (R = 0.41). For subcutaneous fat, the correlation coefficient was 0.66 for SUVmean (p < 0.05). Correlations between MRAC and CTAC were non-significant for SUVmean of the psoas muscle, SUVmax of subcutaneous fat, SUVmax and SUVmean of the lungs, SUVmax and SUVmean of the blood-pool. The median SUVmax and SUVmean in MRAC-PET were lower than the respective CTAC values in all organs (p < 0.05) but heart (SUVmax) and the bone marrow (SUVmean).

Conclusion

In conclusion, in oncologic patients examined with PET/CT and PET/MRI SUVmax and SUVmean values generally correlate well in normal organ tissues, except the lung, subcutaneous fat and the blood pool. SUVmax and SUVmean derived from PET/MRI can be used reliably in clinical routine.     

Bone metastasis in patients with non-small cell lung cancer: The diagnostic role of F-18 FDG PET/CT

Purpose

To evaluate the performance of F-18 FDG PET/CT in the detection of bone metastasis in non-small cell lung cancer (NSCLC) patients.

Materials and methods

Three hundred and sixty-two consecutive NSCLC patients who underwent F-18 FDG PET/CT scanning were retrospectively analyzed. Each image of PET/CT, combined CT, and PET was performed at 10 separate areas and interpreted blindly and separately. The sensitivity, specificity and accuracy of F-18 FDG PET/CT, combined CT and F-18 FDG PET were calculated and the results were statistically analyzed.

Results

Bone metastasis was confirmed in 82 patients with 331 positive segments based on the image findings and clinical follow-up. On patient-based analysis, the sensitivity of F-18 FDG PET/CT (93.9%) was significantly higher than those of combined CT (74.4%) and F-18 FDG PET (84.1%), respectively (p < 0.05). The overall specificity and accuracy of combined CT, F-18 FDG PET, and F-18 FDG PET/CT were 90.7%, 93.2%, 98.9% and 87.0%, 91.2%, and 97.8%, respectively (compared with PET/CT, p < 0.05). On segment-based analysis, the sensitivity of the three modalities were 79.5%, 94.3%, and 98.8%, respectively (compared with PET/CT, p < 0.05). The overall specificity and accuracy of the three modalities were 87.9%, 89.2%, 98.6% and 84.5%, 91.2%, 98.7%, respectively (compared with PET/CT, p < 0.05).

Conclusion

F-18 FDG PET/CT is superior to F-18 FDG PET or combined CT in detecting bone metastasis of NSCLC patients because of the complementation of CT and PET. It is worth noting that the added value of F-18 FDG PET/CT may beneficially impact the clinical management of NSCLC.     

Prognostic significance of novel F-FDG PET/CT defined tumour variables in patients with oesophageal cancer

Purpose

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) combined with computed tomography (PET/CT) is now established as a routine staging investigation of oesophageal cancer (OC). The aim of the study was to determine the prognostic significance of PET/CT defined tumour variables including maximum standardised uptake value (SUVmax), tumour length (TL), metastatic length of disease (MLoD), metabolic tumour volume (MTV), total lesion glycolysis (TLG) and total local nodal metastasis count (PET/CT LNMC).

Materials and methods

103 pre-treatment OC patients (76 adenocarcinoma, 25 squamous cell carcinoma, 1 poorly differentiated and 1 neuroendocrine tumour) were staged using PET/CT. The prognostic value of the measured tumour variables were tested using log-rank analysis of the Kaplan–Meier method and Cox's proportional hazards method. Primary outcome measure was survival from diagnosis.

Results

Univariate analysis showed all variables to have strong statistical significance in relation to survival. Multivariate analysis demonstrated three variables that were significantly and independently associated with survival; MLoD (HR 1.035, 95% CI 1.008–1.064, p = 0.011), TLG (HR 1.002, 95% CI 1.000–1.003, p = 0.018) and PET/CT LNMC (HR 0.048–0.633, 95% CI 0.005–2.725, p = 0.015).

Conclusion

MLoD, TLG, and PET/CT LNMC are important prognostic indicators in OC. This is the first study to demonstrate an independent statistical association between TLG, MLoD and survival by multivariable analysis, and highlights the value of staging OC patients with PET/CT using functional tumour variables.     

Combined pre-treatment MRI and 18F-FDG PET/CT parameters as prognostic biomarkers in patients with cervical cancer

Objective

To determine the associations of quantitative parameters derived from multiphase contrast-enhanced magnetic resonance imaging (CE-MRI), diffusion-weighted (DW) MRI and 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography/computed tomography (PET/CT) with clinico-histopathological prognostic factors, disease-free survival (DFS) and overall survival (OS) in patients with cervical cancer.

Methods and materials

Our institutional review board approved this retrospective study of 49 patients (median age, 45 years) with histopathologically proven IB-IVB International Federation of Gynecology and Obstetrics (FIGO) cervical cancer who underwent pre-treatment pelvic MRI and whole-body 18F-FDG PET/CT between February 2009 and May 2012. Maximum diameter (_maxTD), percentage enhancement (PE) and mean apparent diffusion coefficient (ADC_mean) of the primary tumor were measured on MRI. Maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV), total lesion glycolysis (TLG) were measured on 18F-FDG PET/CT. Correlations between imaging metrics and clinico-histopathological parameters including revised 2009 FIGO stage, tumor histology, grade and lymph node (LN) metastasis at diagnosis were evaluated using the Wilcoxon rank sum test. Cox modeling was used to determine associations with DFS and OS.

Results

Median follow-up was 17 months. 41 patients (83.6%) were alive. 8 patients (16.3%) died of disease. Progression/recurrence occurred in 17 patients (34.6%). Significant differences were observed in ADC_mean, SUV_max, MTV and TLG according to FIGO stage (p < 0.001–0.025). There were significant correlations between ADC_mean, MTV, TLG and LN metastasis (p = 0.017–0.032). SUV_max was not associated with LN metastasis. FIGO stage (p = 0.017/0.033), LN metastases (p = 0.001/0.020), ADC_mean (p = 0.007/0.020) and MTV (p = 0.014/0.026) were adverse predictors of both DFS/OS. _maxTD (p = 0.005) and TLG (p = 0.024) were adverse predictors of DFS. PE and SUV_max did not correlate with DFS or OS (p = 0.18–0.72).

Conclusions

Quantitative parameters derived from pre-treatment DW-MRI (ADC_mean) and from 18F-FDG PET/CT (MTV and TLG) were associated with high-risk features and may serve as prognostic biomarkers of survival in patients with cervical cancer.     

Value of fusion of PET and MRI for staging of endometrial cancer: Comparison with F-FDG contrast-enhanced PET/CT and dynamic contrast-enhanced pelvic MRI

Purpose

To investigate the diagnostic value of retrospective fusion of pelvic MRI and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET images for assessment of locoregional extension and nodal staging of endometrial cancer.

Materials and methods

Thirty patients with biopsy-proven endometrial cancer underwent preoperative contrast-enhanced PET/CT (PET/ceCT) and pelvic dynamic contrast-enhanced MRI for initial staging. Diagnostic performance of PET/ceCT, contrast-enhanced MRI, and retrospective image fusion from PET and MRI (fused PET/MRI) for assessing the extent of the primary tumor (T stage) and metastasis to regional LNs (N stage) was evaluated by two experienced readers. Histopathological and follow-up imaging results were used as the gold standard. The McNemar test was employed for statistical analysis.

Results

Fused PET/MRI and MRI detected 96.7% of the primary tumors, whereas PET/ceCT detected 93.3%. Accuracy for T status was 80.0% for fused PET/MRI, and MRI proved significantly more accurate than PET/ceCT, which had an accuracy of 60.0% (p = 0.041). Patient-based sensitivity, specificity and accuracy for detecting pelvic nodal metastasis were 100%, 96.3% and 96.7% for both fused PET/MRI and PET/ceCT, and 66.7%, 100% and 96.7% for MRI, respectively. These three parameters were not statistically significant (p = 1).

Conclusion

Fused PET/MRI, which complements the individual advantages of MRI and PET, is a valuable technique for assessment of the primary tumor and nodal staging in patients with endometrial cancer.     

The influence of different contrast medium concentrations and injection protocols on quantitative and clinical assessment of FDG–PET/CT in lung cancer

Objectives

To compare the effects of two different contrast medium concentrations for use in computed X-ray tomography (CT) employing two different injection protocols on positron emission tomography (PET) reconstruction in combined 2-¹⁸F-desoxyglucose (FDG) PET/CT in patients with a suspicion of lung cancer.

Methods

120 patients with a suspicion of lung cancer were enrolled prospectively. PET images were reconstructed with the non-enhanced and venous phase contrast CT obtained after injection of iopromide 300 mg/ml or 370 mg/ml using either a fixed-dose or a body surface area adapted injection protocol. Maximum and mean standardized uptake values (SUVmax and SUVmean) and contrast enhancement (HU) were determined in the subclavian vein, ascending aorta, abdominal aorta, inferior vena cava, portal vein, liver and kidney and in the suspicious lung lesion. PET data were evaluated visually for the presence of malignancy and image quality.

Results

At none of the sites a significant difference in the extent of the contrast enhancement between the four different protocols was found. However, the variability of the contrast enhancement at several anatomical sites was significantly greater in the fixed dose groups than in the BSA groups for both contrast medium concentrations. At none of the sites a significant difference was found in the extent of the SUVmax and SUVmean increase as a result of the use of the venous phase contrast enhanced CT for attenuation. Visual clinical evaluation of lesions showed no differences between contrast and non-contrast PET/CT (P = 0.32).

Conclusions

Contrast enhanced CT for attenuation correction in combined PET/CT in lung cancer affects neither the clinical assessment nor image quality of the PET-images. A body surface adapted contrast medium protocol reduces the interpatient variability in contrast enhancement.