The role of metabolic tumor volume and total lesion glycolysis on 18F-FDG PET/CT in the prognosis of epithelial ovarian cancer

Purpose

This study assessed the prognostic value of pre-operative 2-[¹⁸F] fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) volumetric parameters, including metabolic tumor volume (MTV) and total lesion glycolysis (TLG), in patients with epithelial ovarian cancer.

Methods

A total of 175 patients with epithelial ovarian cancer who underwent ¹⁸?F-FDG PET/CT and subsequent cytoreductive surgery were retrospectively enrolled. Maximum standardized uptake value (SUVmax) on ¹⁸F-FDG PET/CT was measured for all patients. Because nine patients showed low tumor-to-background uptake ratios, MTV and TLG were measured in 166 patients. Univariate and multivariate analyses were performed to evaluate the prognostic significance of SUVmax, MTV, TLG, and clinicopathological factors for disease progression-free survival.

Results

Disease progressed in 78 (44.6 %) of the 175 patients, and the 2-year disease progression-free survival rate was 57.5 %. Univariate analysis showed that tumor stage, histopathological type, presence of regional lymph node metastasis, residual tumor after cytoreductive surgery, pre-operative serum carbohydrate antigen 125 (CA125) level, SUVmax, MTV, and TLG were significant prognostic factors (p?100.0).

Conclusion

Along with tumor stage, TLG is an independent prognostic factor for disease progression after cytoreductive surgery in patients with epithelial ovarian cancer. By combining tumor stage and TLG, one can further stratify the risk of disease progression for patients undergoing cytoreductive surgery.     

Role of [18F]FDG PET in prediction of KRAS and EGFR mutation status in patients with advanced non-small-cell lung cancer

Purpose

The tumour molecular profile predicts the activity of epidermal growth factor receptor (EGFR) inhibitors in non-small-cell lung cancer (NSCLC). However, tissue availability and tumour heterogeneity limit its assessment. We evaluated whether [¹⁸F]FDG PET might help predict KRAS and EFGR mutation status in NSCLC.

Methods

Between January 2005 and October 2011, 340 NSCLC patients were tested for KRAS and EGFR mutation status. We identified patients with stage III and IV disease who had undergone [¹⁸F]FDG PET/CT scanning for initial staging. SUVpeak, SUVmax and SUVmean of the single hottest tumour lesions were calculated, and their association with KRAS and EGFR mutation status was assessed. A receiver operator characteristic (ROC) curve analysis and a multivariate analysis (including SUVmean, gender, age and AJCC stage) were performed to identify the potential value of [¹⁸F]FDG PET/CT for predicting KRAS mutation.

Results

From 102 patients staged using [¹⁸F]FDG PET/CT, 28 (27 %) had KRAS mutation (KRAS+), 22 (22 %) had EGFR mutation (EGFR+) and 52 (51 %) had wild-type KRAS and EGFR profiles (WT). KRAS+ patients showed significantly higher [¹⁸F]FDG uptake than EGFR+ and WT patients (SUVmean 9.5, 5.7 and 6.6, respectively; p?18F]FDG uptake between EGFR+ patients and WT patients. ROC curve analysis for KRAS mutation status discrimination yielded an area under the curve of 0.740 for SUVmean (p?Conclusion NSCLC patients with tumours harbouring KRAS mutations showed significantly higher [¹⁸F]FDG uptake than WT patients, as assessed in terms of SUVpeak, SUVmax and SUVmean. A multivariate model based on age, gender, AJCC stage and SUVmean might be used as a predictive marker of KRAS mutation status in patients with stage III or IV NSCLC.     

Performance of FDG PET/CT at initial diagnosis in a rare lymphoma: nodular lymphocyte-predominant Hodgkin lymphoma

Purpose

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare Hodgkin lymphoma distinguished from classical Hodgkin lymphoma (cHL) by the nature of the neoplastic cells which express B-cell markers. We wanted to determine the diagnostic performance of FDG PET/CT in initial assessment and its therapeutic impact on staging.

Methods

We retrospectively studied a population of 35 patients with NLPHL (8 previously treated for NLHPL, 27 untreated). All patients underwent an initial staging by pretherapeutic FDG PET/CT. The impact on initial stage or relapse stage was assessed by an independent physician.

Results

In a per-patient analysis, the sensitivity of the pretherapeutic FDG PET/CT was 100 %. In a per-site analysis, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of pretherapeutic FDG PET/CT were 100 %, 99 %, 97 %, 100 % and 99 %, respectively. Pretherapeutic FDG PET/CT led to a change in the initial stage/relapse stage in 12 of the 35 patients (34 %). In contrast to previous results established without FDG PET/CT, 20 % of patient had osteomedullary lesions.

Conclusion

Pretherapeutic FDG PET/CT has excellent performance for initial staging or relapse staging of NLPHL.     

Asphericity of pretherapeutic tumour FDG uptake provides independent prognostic value in head-and-neck cancer

Objective

To propose a novel measure, namely the ‘asphericity’ (ASP), of spatial irregularity of FDG uptake in the primary tumour as a prognostic marker in head-and-neck cancer.

Methods

PET/CT was performed in 52 patients (first presentation, n?=?36; recurrence, n?=?16). The primary tumour was segmented based on thresholding at the volume-reproducible intensity threshold after subtraction of the local background. ASP was used to characterise the deviation of the tumour’s shape from sphere symmetry. Tumour stage, tumour localisation, lymph node metastases, distant metastases, SUV_max, SUV_mean, metabolic tumour volume (MTV) and total lesion glycolysis (TLG) were also considered. The association of overall (OAS) and progression-free survival (PFS) with these parameters was analysed.

Results

Cox regression revealed high SUV_max [hazard ratio (HR)?=?4.4/7.4], MTV (HR?=?4.6/5.7), TLG (HR?=?4.8/8.9) and ASP (HR?=?7.8/7.4) as significant predictors with respect to PFS/OAS in case of first tumour manifestation. The combination of high MTV and ASP showed very high HRs of 22.7 for PFS and 13.2 for OAS. In case of recurrence, MTV (HR?=?3.7) and the combination of MTV/ASP (HR?=?4.2) were significant predictors of PFS.

Conclusions

ASP of pretherapeutic FDG uptake in the primary tumour improves the prediction of tumour progression in head-and-neck cancer at first tumour presentation.

Key Points

?Asphericity (ASP) characterises the spatial heterogeneity of FDG uptake in tumours ? ASP is a promising prognostic parameter in head-and-neck cancer ? ASP is useful for identification of high-risk patients with head-and-neck cancer     

Perfusion-metabolism coupling in recurrent gliomas: a prospective validation study with 13N-ammonia and 18F-fluorodeoxyglucose PET/CT

Introduction

We assessed the validity of “perfusion-metabolism coupling” hypothesis in recurrent glioma with ¹³N-ammonia (¹³N-NH₃) PET/CT and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET/CT.

Methods

Fifty-six consecutive patients (age, 38.8?±?12.1 years; 62.5 % males) with histologically proven and previously treated glioma presenting with clinical suspicion of recurrence were prospectively enrolled and evaluated with ¹³N-NH₃ PET/CT and ¹⁸F-FDG PET/CT. PET/CT images were evaluated both qualitatively and semiquantitatively. Tumor to white matter uptake ratio (T/W) and tumor to gray matter uptake ratio (T/G) were calculated and analyzed for both the modalities. A combination of clinico-radiological follow-up, repeated imaging, and biopsy (when available) were considered as the reference standard.

Results

Based on the reference standard, 27/56 patients had recurrence. ¹³N-NH₃ PET/CT and ¹⁸F-FDG PET/CT were concordant in 55/56 patients. Overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ¹³N-NH₃PET/CT were 77.8, 86.2, 84.0, 80.7, and 82.1 %, respectively, and for ¹⁸F-FDG PET/CT were 77.8, 89.7, 87.5, 81.2, and 83.9 %, respectively. There was excellent agreement between results of ¹³N-NH₃ PET/CT and ¹⁸F-FDG PET/CT (??=?0.964; P?13N-NH₃ PET/CT and ¹⁸F-FDG PET/CT were not significantly different between high-grade and low-grade glioma (P?=?1.000). A strong positive correlation was noted between the uptake ratios derived on the two modalities (ρ?=?0.866, P?ρ?=?0.918, P?Conclusion A combination of ¹³N-NH₃ PET/CT and ¹⁸F-FDG PET/CT demonstrates that perfusion and metabolism are coupled in recurrent gliomas. These tracers target two different but interrelated aspects of the same pathologic process and can be used as surrogates for each other.     

Assessment of aortitis by semiquantitative analysis of 180-min 18F-FDG PET/CT acquisition images

Purpose

The aim of this study was to evaluate the contribution of semiquantitative analysis of 180-min ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT images for the assessment of aortitis in cases of suspected large vessel vasculitis (LVV) and to establish a threshold index for application in the clinical setting.

Methods

This prospective study included 43 patients (mean age 67.5?±?12.9?years) with suspicion of LVV (25 with a final diagnosis of aortitis). ¹⁸F-FDG PET/CT scan was acquired 180 min after injection of 7 MBq/kg of ¹⁸F-FDG. A semiquantitative analysis was performed calculating the aortic wall maximum standardized uptake value (SUV_max) (T), the lumen SUV_max (B) and the target to background ratio (TBR). These results were also compared with those obtained in a control population.

Results

The mean aortic wall SUV_max was 2.00?±?0.62 for patients with aortitis and 1.45?±?0.31 for patients without aortitis (p?p?max (0.997 vs 0.871). The highest sensitivity and specificity was obtained for a TBR of 1.34 (sensitivity 100 %, specificity 94.4 %).

Conclusion

Semiquantitative analysis of PET/CT images acquired 180 min after ¹⁸F-FDG injection and the TBR index of 1.34 show very high accuracy and, therefore, are strongly recommended for the diagnosis of aortitis in the clinical setting.     

Correlation between 18F-fluoromisonidazole PET and expression of HIF-1α and VEGF in newly diagnosed and recurrent malignant gliomas

Purpose

Hypoxia and its consequences at the molecular level promote tumour progression and affect patient prognosis. One of the main early cellular events evoked by hypoxia is induction of hypoxia-inducible factor 1 (HIF-1) and subsequent upregulation of vascular endothelial growth factor (VEGF). In this study we sought to determine whether hypoxia detected by ¹⁸F-fluoromisonidazole (FMISO) PET accurately reflects the expression of HIF-1α and VEGF in the tumour and can be used as a biomarker of antiangiogenic treatment and as a prognostic factor in newly diagnosed and recurrent malignant gliomas.

Methods

Enrolled in this study were 32 patients with newly diagnosed glioma and 16 with recurrent glioma of grade III or grade IV. All the patients had undergone FMISO PET preoperatively. The maximum tumour-to-blood FMISO activity ratio (T/B_max) was used to evaluate the degree of tumour hypoxia and the hypoxic volume (HV) was calculated using a tumour-to-blood FMISO uptake ratio of ≥1.2. Immunohistochemical expressions of HIF-1α and VEGF were evaluated semiquantitatively using the immunoreactivity score (IRS, scores 0 to 12) and the correlation was examined between IRS of HIF-1α or VEGF and FMISO uptake of the tumour (SUV_tumour) using navigation-based sampling. Survival was estimated using the Kaplan-Meier method in relation to the T/B_max and the HV.

Results

The T/B_max and the HV in grade IV gliomas were significantly higher than in grade III gliomas (P?P?VEGF expression was observed in the majority of malignant gliomas. The IRS of HIF-1α and VEGF in the tumour were not significantly different between grade III and grade IV gliomas. The IRS of HIF-1α in the tumour did not correlate with the SUV_tumour of FMISO in either newly diagnosed or recurrent glioma. There was a significant but weak correlation between the IRS of VEGF and the SUV_tumour of FMISO in newly diagnosed glioma, but not in recurrent glioma. The overall survival time in patients with a small HV and a low FMISO T/B_max was significantly longer than in those with a large HV and a high FMISO T/B_max (P?P?Conclusion Preoperative FMISO uptake is significantly correlated with the expression of VEGF in the tumour and might be used as a biomarker of antiangiogenic treatment in newly diagnosed malignant gliomas. However, caution is required because the correlation was weak and there was a large overlap of FMISO uptake between glioma with high and low VEGF expression. In addition, hypoxia determined by FMISO PET appears to be a suitable biomarker for predicting a highly malignant tumour and a poor prognosis in patients with malignant glioma.     

Advantage of FMISO-PET over FDG-PET for predicting histological response to preoperative chemotherapy in patients with oral squamous cell carcinoma

Purpose

Hypoxia, a prognostic factor in many types of cancer, can be detected by ¹⁸F-fluoromisonidazole (FMISO) positron emission tomography (PET). It is unclear whether hypoxia reflects the response to chemotherapy in patients with oral squamous cell carcinoma (OSCC). The correlations of FMISO-PET and FDG-PET with histological response to preoperative chemotherapy were therefore assessed in patients with OSCC.

Methods

This study enrolled 22 patients with OSCC undergoing preoperative chemotherapy. The T-stages were T2 in 6 patients, T3 in 3, and T4a in 13, and the N-stages were N0 in 14 patients, N1 in 3, and N2 in 5. Each patient was evaluated by both FMISO-PET and FDG-PET before surgery, and the maximum standardized uptake value (SUV_max) of FDG- and FMISO-PET and tumor-muscle ratio (TMR) of FMISO-PET were measured. The threshold for the hypoxic volume based on TMR was set at 1.25. The histological response to preoperative chemotherapy was evaluated using operative materials.

Results

FMISO-PET and FDG-PET detected uptake by primary OSCCs in 15 (68 %) and 21 (95 %) patients, respectively, and median SUV_maxs of FMISO- and FDG-PET in the primary site were 2.0 (range, 1.3–3.5) and 16.0 (range, 1.0–32.2), respectively. The median of FMISO TMR was 1.5 (range, 0.99–2.96). There were five cases whose FMISO TMR was less than 1.25. Histological evaluation showed good response to preoperative chemotherapy in 7 patients (32 %) and poor response in 15 (68 %). Good response was significantly more prevalent in patients with negative than positive FMISO uptake (P?P?=?0.04), whereas FDG uptake was not significantly correlated with response to chemotherapy response. Multivariate logistic regression analysis showed that FMISO uptake was an independent significant predictor of response to preoperative chemotherapy (P?=?0.03, odds ratio?=?0.06, 95 % confidence interval?=?0.004–0.759).

Conclusions

An advantage of FMISO-PET over FDG-PET for predicting histological response to preoperative chemotherapy in patients with OSCC was observed.     

Impact of 18F-FDG PET/CT on the management of adrenocortical carcinoma: analysis of 106 patients

Purpose

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy. Limited data are available about on value of ¹⁸F-FDG PET/CT in ACC. We evaluated the impact of PET/CT on the management of ACC.

Methods

We performed a retrospective review in patients with ACC who had undergone PET/CT. The impact of PET/CT on the management plan was evaluated by comparing the findings on PET/CT to the findings on contrast-enhanced CT. The sensitivity, specificity, and accuracy of each form of imaging were calculated. The correlations between PET/CT parameters, including maximum standardized uptake value (SUV_max), total lesion glycolysis, and decline in SUV_max after chemotherapy, and clinical outcome were evaluated.

Results

Included in the analysis were 106 patients with 180 PET/CT scans. Of the 106 patients, 7 underwent PET/CT only for initial staging, 84 underwent PET/CT only for restaging, and 15 underwent PET/CT for both initial staging and restaging. PET/CT changed the management plan in 1 of 22 patients (5 %) at initial staging and 9 of 99 patients (9 %) at restaging. In 5 of the patients in whom PET/CT changed the management plan, PET/CT showed response to chemotherapy but contrast-enhanced CT showed stable disease. Sensitivity, specificity, and accuracy were 100 %, 100 %, and 100 % for PET/CT at initial staging; 92.6 %, 100 %, and 96.4 % for CT at initial staging; 98.4 %, 100 %, and 99.5 % for PET/CT at restaging; and 96.8 %, 98.6 %, and 98.0 % for CT at restaging, respectively. No PET/CT parameters were associated with survival at either initial diagnosis or recurrence.

Conclusion

PET/CT findings could substantially change the management plan in a small proportion of patients with ACC. Although lesion detection was similar between PET/CT and CT, PET/CT may be preferred for chemotherapeutic response assessment because it may predict response before anatomic changes are detected on CT.     

Routine use of dual time 18F-FDG PET for staging of preoperative lung cancer: does it affect clinical management?

Objective

The objective of this study was to compare the diagnostic accuracy of dual-time-point 18F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) to single-time-point ¹⁸F-FDG PET for staging of preoperative lung cancer.

Methods

Between November 2008 and December 2009, 107 patients who were diagnosed as having lung cancer or strongly suspected of having lung cancer were enrolled. They underwent dual-time-point ¹⁸F-FDG PET following conventional imaging. Dual-time-point ¹⁸F-FDG PET imaging (whole body) was performed at 1-h (early) post-FDG injection and repeated (2 h delayed) after injection. The diagnostic accuracy of pre-PET staging and post-PET staging was retrospectively evaluated, and the diagnostic accuracy of dual-time-point ¹⁸F-FDG PET was compared to that of single-time-point ¹⁸F-FDG PET.

Results

In 100 patients, the early ¹⁸F-FDG PET scan resulted in upstaging of the tumor in ten (10 %) and down-staging of the tumor in five (5 %) compared to the conventional scan. The delayed phase of ¹⁸F-FDG PET provided no additional information on staging for lung cancer patients. The remaining seven patients were diagnosed as not having lung cancer.

Conclusion

This study confirmed that dual-time-point ¹⁸F-FDG PET is useful for differential diagnosis between benign and malignant lesions, but has no major impact on staging and therapeutic management of patients with pathologically proven lung cancer.     

Stereotactic body radiotherapy for liver tumors

Purpose

This report of the Working Group on Stereotactic Radiotherapy of the German Society of Radiation Oncology (DEGRO) aims to provide a practical guideline for safe and effective stereotactic body radiotherapy (SBRT) of liver tumors.

Methods

The literature on the clinical evidence of SBRT for both primary liver tumors and liver metastases was reviewed and analyzed focusing on both physical requirements and special biological characteristics.

Results

Recommendations were developed for patient selection, imaging, planning, treatment delivery, motion management, dose reporting, and follow-up. Radiation dose constraints to critical organs at risk are provided.

Conclusion

SBRT is a well-established treatment option for primary and secondary liver tumors associated with low morbidity.     

Inferior glucose metabolism and chemosensitivity of post-radiotherapy local recurrence in comparison with distant metastases as assessed by sequential 18F-FDG PET/CT imaging

Purpose

To compare glucose metabolism and chemosensitivity between recurrence within the irradiation field and metastases outside the irradiation field in the same patient using ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography images (PET/CT).

Methods

The ¹⁸F-FDG PET/CT images of 43 cancer patients with both local recurrence (in-field) and distal metastases (out-field) after initial treatments were reviewed. 23 patients after definitive radiotherapy/chemoradiotherapy and 20 patients after radical surgery were assigned to a radiation group and surgery group, respectively. The tumor maximal diameter on CT and PET images (D _CT and D _PET), maximal SUV (SUV_max), and mean SUV (SUV_mean) were measured. All the patients were administered chemotherapy, and 17 patients from the radiation group and 10 patients from the surgery group underwent PET/CT scanning within 1–2 months after the treatment. The changes in D _CT, D _PET, SUV_max and SUV_mean for each lesion were calculated and compared between in-field and out-field tumors for both groups.

Results

In the surgery group, no significant difference was found in tumor size or FDG uptake between the local recurrence and metastases. In the radiation group, both SUV_max (7.03 ± 3.48) and SUV_mean (4.33 ± 1.67) of the in-field tumors were lower than those (8.45 ± 4.34 and 5.36 ± 2.51, respectively, P < 0.05) of out-field tumors. Moreover, the response extent of in-field tumors was lower than that of out-field tumors in the radiation group (P < 0.05). However, in the surgery group, there was no difference in the response extent (tumor size and SUVs) between the local recurrence and metastases (P > 0.05).

Conclusion

The recurrence within the irradiation field and metastases outside the irradiation field in the same patient do not share the same biological characteristics or treatment response, with inferior glucose metabolism and chemosensitivity seen in locally recurrent tumors.     

The diagnostic value of SE MRI and DWI of the spine in patients with monoclonal gammopathy of undetermined significance,smouldering myeloma and multiple myeloma

Objectives

To evaluate DWI of the bone marrow in the differentiation of monoclonal gammopathy of undetermined significance (MGUS), smouldering myeloma (SMM) and multiple myeloma (MM).

Methods

The retrospective study includes 64 patients with MGUS, 27 with SMM, 64 with new MM and 12 controls. Signal intensity (SI) of spinal SE-MRI and DWI (b0-1000) as well as apparent diffusion coefficients (ADC) were measured in the T10 and L3. Qualitative assessment of b-images was performed by one experienced radiologist.

Results

ADC600 and ADC1000 are the best ADC values in differentiating patient groups (p?p?MGUS and MM (p?50 % (p?=?0.001). Only SIT2 for L3 can differentiate MGUS from SMM (p?=?0.044) and PC%0-10 from PC%10-25 (p?=?0.033). Qualitative interpretation of b1000 images allows differentiating MM patients from those with MGUS or SMM (p?Conclusions Spinal SE-MRI can differentiate among MGUS, SMM, MM and control subjects. DWI based on the SI on b1000 images and ADC values is increased in MM compared to MGUS and SMM. Qualitative assessment of b-images can differentiate MM from MGUS or SMM.

Key points

? ADC values are higher in patients with MM compared to MGUS ? DWI parameters change late in disease evolution ? DWI is sensitive but not specific in diagnosing patients with MM ? Qualitative DWI assessment is good in detecting myeloma patients     

Prognostic Value of Metabolic Tumor Volume Estimated by 18 F-FDG Positron Emission Tomography/Computed Tomography in Patients with Diffuse Large B-Cell Lymphoma of Stage II or III Disease

Purpose

The purpose of this study was to evaluate the prognostic value of metabolic tumor volume (MTV) measured by ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET/CT) in patients with diffuse large B-cell lymphoma (DLBCL) treated with rituximab-containing immunochemotherapy.

Methods

Patients with newly diagnosed DLBCL who underwent pre-treatment torso FDG-PET/CT scan taken within 10 days before treatment were included. MTV was defined as the volume of hypermetabolic tissue with a standardized uptake value (SUV) greater than a threshold value of 2.5 and calculated using volume viewer software. Association of MTV with patient characteristics and survival were compared.

Results

A total of 96 patients were evaluated. During a median follow-up period of 27.8 months, 3-year event-free survival (EFS) and overall survival was 69.5 % and 72.9 %, respectively. The Ann Arbor staging showed a limitation of prognosis because there was no difference of EFS between patients with Ann Arbor stage II and those with stage III. On the contrary, among patients with Ann Arbor stage II or III disease (n?=?53), the higher MTV group showed significantly inferior EFS compared with the lower MTV group.

Conclusions

In the current study, we identified the pre-treatment MTV measured by FDG-PET/CT as a potential predictor of survival in patients with DLBCL treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP), at least in Ann Arbor stage II and III disease.     

Performance of 18F-FDG PET/CT as a postoperative surveillance imaging modality for asymptomatic advanced gastric cancer patients

Objective

The purpose of this study was to investigate the diagnostic performance of postoperative fluorine-18 fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) as a surveillance modality for advanced gastric cancer patients who were asymptomatic and negative by conventional follow-up.

Methods

We retrospectively collected 46 advanced gastric cancer patients who received approximately 1-year-postoperative ¹⁸F-FDG PET/CT surveillance following curative resection (mean age 60.6 ± 11.5 years). ¹⁸F-FDG PET/CT was interpreted by nuclear medicine physicians who were blind to the clinical information. Final confirmation was determined by clinical follow-up using tumor markers, conventional CT scan, upper gastrointestinal endoscopy and with/without subsequent histopathologic diagnosis.

Results

Four patients developed recurrence (8.7 %; 1 local and 3 distant recurrences). For local recurrence, ¹⁸F-FDG PET/CT found four hypermetabolic lesions and one was local recurrence. For distant recurrence, seven hypermetabolic lesions were found in six patients and true-positive was three lesions. False-positive cases were mainly turned out to be physiologic small bowel uptake. Regardless of the recurrence site, the sensitivity, specificity, positive predictive value and negative predictive value of ¹⁸F-FDG PET/CT were 100 % (4/4, 95 % confidence interval (CI) 39.6–100 %), 88.1 % (37/42, 95 % CI 73.6–95.5 %), 44.4 % (4/9, 95 % CI 15.3–77.3 %) and 100 % (37/37, 95 % CI 88.3–100 %), respectively in the patient-based analysis.

Conclusion

Our study showed good specificity of postoperative surveillance ¹⁸F-FDG PET/CT for detecting recurrence. Careful caution should be made for interpreting some false-positive hypermetabolic lesions in postoperative ¹⁸F-FDG PET/CT, especially at the local anastomosis site.     

Value of 18F-FDG uptake on PET/CT and CEA level to predict epidermal growth factor receptor mutations in pulmonary adenocarcinoma

Purpose

The identification of the mutation status of the epidermal growth factor receptor (EGFR) is important for the optimization of treatment in patients with pulmonary adenocarcinoma. The acquisition of adequate tissues for EGFR mutational analysis is sometimes not feasible, especially in advanced-stage patients. The aim of this study was to predict EGFR mutation status in patients with pulmonary adenocarcinoma based on ¹⁸F-fluorodeoxyglucose (FDG) uptake and imaging features in positron emission tomography/computed tomography (PET/CT), as well as on the serum carcinoembryonic antigen (CEA) level.

Methods

We retrospectively reviewed 132 pulmonary adenocarcinoma patients who underwent EGFR mutation testing, pretreatment FDG PET/CT and serum CEA analysis. The associations between EGFR mutations and patient characteristics, maximal standard uptake value (SUVmax) of primary tumors, serum CEA level and CT imaging features were analyzed. Receiver-operating characteristic (ROC) curve analysis was performed to quantify the predictive value of these factors.

Results

EGFR mutations were identified in 69 patients (52.2 %). Patients with SUVmax ≥6 (p?=?0.002) and CEA level ≥5 (p?=?0.013) were more likely to have EGFR mutations. The CT characteristics of larger tumors (≥3 cm) (p?=?0.023) and tumors with a nonspiculated margin (p?=?0.026) were also associated with EGFR mutations. Multivariate analysis showed that higher SUVmax and CEA level, never smoking and a nonspiculated tumor margin were the most significant predictors of EGFR mutation. The combined use of these four criteria yielded a higher area under the ROC curve (0.82), suggesting a good discrimination.

Conclusion

The combined evaluation of FDG uptake, CEA level, smoking status and tumor margins may be helpful in predicting EGFR mutation status in patients with pulmonary adenocarcinoma, especially when the tumor sample is inadequate for genetic analysis or genetic testing is not available. Further large-scale prospective studies are needed to validate these results.     

Physiologic characterization of inflammatory arthritis in a rabbit model with BOLD and DCE MRI at 1.5 Tesla

Objective

Our aim was to test the feasibility of blood oxygen level dependent magnetic resonance imaging (BOLD MRI) and dynamic contrast-enhanced (DCE) MRI to monitor periarticular hypoxic/inflammatory changes over time in a juvenile rabbit model of arthritis.

Methods

We examined arthritic and contralateral nonarthritic knees of 21 juvenile rabbits at baseline and days 1,14, and 28 after induction of arthritis by unilateral intra-articular injection of carrageenin with BOLD and DCE MRI at 1.5 Tesla (T). Nine noninjected rabbits served as controls. Associations between BOLD and DCE-MRI and corresponding intra-articular oxygen pressure (PO₂) and blood flow [blood perfusion units (BPU)] (polarographic probes, reference standards) or clinical–histological data were measured by correlation coefficients.

Results

Percentage BOLD MRI change obtained in contralateral knees correlated moderately with BPU on day 0 (r?=??0.51, p?=?0.02) and excellently on day 28 (r?=??0.84, p?=?0.03). A moderate correlation was observed between peak enhancement DCE MRI (day 1) and BPU measurements in arthritic knees (r?=?0.49, p?=?0.04). In acute arthritis, BOLD and DCE MRI highly correlated (r?=?0.89, p?=?0.04; r?=?1.0, p?Conclusion The proposed techniques are feasible to perform at 1.5 T, and they hold potential as surrogate measures to monitor hypoxic and inflammatory changes over time in arthritis at higher-strength MRI fields.

Key points

? BOLD and DCE MRI detect interval perisynovial changes in a rabbit knee ? BOLD and DCE MRI act as surrogate markers of physiologic changes in arthritis ? BOLD MRI signal represents oxygen extraction compared with intra-articular PO ₂ ? DCE MRI measurements estimate physiologic periarticular vascular properties ? In rabbit knees with acute arthritis, BOLD/DCE MRI highly correlated with histological scores     

The diagnostic role of 18F-FDG PET for primary central nervous system lymphoma

Objective

¹⁸F-FDG PET has become one of the most important methods for studying malignant lymphoma, but its diagnostic role for primary central nervous system lymphoma (PCNSL) has not been established. The aim of this study was to determine the appropriate cut-off values of FDG uptake and to investigate how corticosteroid administration influences PCNSL.

Methods

We retrospectively reviewed 82 patients with contrast-enhanced brain tumors who underwent an FDG PET scan at onset, including 19 PCNSLs. FDG uptake of the lesion was assessed by the maximum standardized uptake value (SUVmax) and the ratio of tumor to normal contralateral cortex activity (T/N ratio). Receiver operating characteristic (ROC) curves were generated from the SUVmax and T/N ratios. To investigate the influence of corticosteroid application before a FDG PET scan, we evaluated the association between the FDG uptake of the lesion and the cumulative dose of corticosteroid administration on 13 PCNSL patients who had received steroid treatment before an FDG PET examination.

Results

The mean FDG SUVmax and T/N ratio of PCNSLs were 22.6 and 2.79, respectively, and these values were significantly higher than those of the other malignant brain tumors. ROC analysis indicated that the evaluation of FDG uptake using the T/N ratio was more reliable than the SUVmax with respect to the differential diagnosis. When PCNSL patients went without steroid application before FDG PET, the accuracy of the T/N ratio with a cut-off point of 2.0 was 91.1 %, the sensitivity was 94.7 %, and the specificity was 87.3 %. Although there are no significant differences in the FDG T/N ratio for PCNSL patients with or without steroid treatment, a negative correlation was found between the T/N ratio and cumulative dose of corticosteroid before PET study (r = ?0.71, p = 0.032).

Conclusions

We concluded that the T/N ratio was superior to SUVmax for FDG uptake assessment as for distinguishing PCNSLs from other malignant brain tumors; the appropriate T/N ratio cut-off point was 2.0. In addition, FDG uptake could be influenced by cumulative doses of corticosteroid before a PET scan, and thus this fact should be taken into consideration when evaluating FDG PET for PCNSL diagnosis.     

F-18 FDG PET/CT in the evaluation of Takayasu arteritis: An experience from the tropics

Objective

To evaluate the performance parameters of FDG PET/CT in patients with Takayasu arteritis at diagnosis and during immunosuppression.

Methods

Retrospective analysis of 60 FDG PET/CT studies in 51 patients was performed (17 scans at diagnosis out of which 4 had follow-up scans also and 43 scans on immunosuppression). The degree of FDG uptake in the vessels was assessed visually using a 4-point scale and maximum standardized uptake value (SUVmax), SUVratio, extent of vasculitis and association with ESR were calculated.

Results

PET/CT was positive for active vasculitis in all 17 patients at diagnosis. The mean SUVmax and mean SUV ratio of the active areas were 5.1 ± 3.0 and 3.2 ± 1.9, respectively. On immunosuppression, PET scan was positive for active vasculitis in 14/43 (32.5%) scans. The mean SUVmax and mean SUVratio of the active areas were 1.7 ± 2.1 and 0.95 ± 1.2, respectively. There was significant difference between the mean SUVmax and mean SUVratio at diagnosis and on immunosuppression, respectively (P < .01). The median number of vascular segments in each uptake grade group was also statistically different (P < .01) between scans at diagnosis and on immunosuppression. The median ESR level in PET positive scans was 29 mm/hour (2-53), whereas in PET negative scans was 35.5 mm/hour (6-50) and the difference was not statistically significant.

Conclusion

FDG PET/CT showed good sensitivity to detect active vasculitis at diagnosis and during immunosuppression. The change in SUVmax between the successive FDG PET/CT scans may give an objective assessment of response to immunosuppression.     

18F-Fluorocholine PET/CT for localization of hyperfunctioning parathyroid tissue in primary hyperparathyroidism: a pilot study

Purpose

Primary hyperparathyroidism is a common endocrine disorder which is diagnosed biochemically and for which therapy is surgical. A prerequisite for minimally invasive surgery, which minimizes morbidity and cost, is accurate localization of the involved gland(s). The aim of this study was to evaluate the usefulness of ¹⁸F-fluorocholine PET/CT for preoperative localization of hyperfunctioning parathyroid tissue.

Methods

¹⁸F-Fluorocholine PET/CT and conventional parathyroid scintigraphic imaging consisting of ^99mTc-sestaMIBI SPECT/CT, ^99mTc-sestaMIBI dual-phase imaging and ^99mTc-sestaMIBI/pertechnetate subtraction imaging were performed in 24 patients. The diagnostic performance of the imaging methods was compared against histology as the gold standard and postoperative serum Ca²⁺ and iPTH values.

Results

The sensitivity and specificity of ¹⁸F-fluorocholine PET/CT were 92 % and 100 %, respectively, in contrast to 49 % and 100 %, 46 % and 100 %, and 44 % and 100 % for ^99mTc-sestaMIBI SPECT/CT, ^99mTc-sestaMIBI/pertechnetate subtraction imaging and ^99mTc-sestaMIBI dual-phase imaging, respectively. Combined conventional scintigraphic imaging had a sensitivity and specificity of 64 % and 100 %, respectively. The performance of ¹⁸F-fluorocholine PET/CT was superior particularly in patients with multiple lesions or hyperplasia.

Conclusion

¹⁸F-Fluorocholine PET/CT appears to be a promising, effective imaging method for localization of hyperfunctioning parathyroid tissue.