Early response monitoring to neoadjuvant chemotherapy in osteosarcoma using sequential 18 F-FDG PET/CT and MRI

Purpose

We evaluated the potential of sequential fluorine-18 fluorodeoxyglucose (¹⁸?F-FDG) positron emission tomography (PET)/computed tomography (CT) and MRI (PET/MRI) after one cycle of neoadjuvant chemotherapy to predict a poor histologic response in osteosarcoma.

Methods

A prospective study was conducted on 30 patients with osteosarcoma treated with two cycles of neoadjuvant chemotherapy and surgery. All patients underwent PET/MRI before, after one cycle, and after the completion of neoadjuvant chemotherapy, respectively. Imaging parameters [maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor volume based on magnetic resonance (MR) images (MRV)] and their % changes were calculated on each PET/MRI data set, and histological responses were evaluated on the postsurgical specimen.

Results

A total of 17 patients (57 %) exhibited a poor histologic response after two cycles of chemotherapy. Unlike the little volumetric change in MRI, PET parameters significantly decreased after one and two cycles of chemotherapy, respectively. After one cycle of chemotherapy, SUV_max, MTV, and TLG predicted the poor responders. Among these parameters, either MTV ≥ 47 mL or TLG ≥ 190 g after one cycle of chemotherapy was significantly associated with a poor histologic response on multivariate logistic regression analysis (OR 8.98, p?=?0.039). The sensitivity, specificity, and accuracy of these parameters were 71 %, 85 % and 77 %; and 71 %, 85 % and 77 %, respectively.

Conclusion

The histologic response to neoadjuvant chemotherapy in osteosarcoma can be predicted accurately by FDG PET after one course of chemotherapy. Among PET parameters, MTV and TLG were independent predictors of the histologic response.     

Assessment of histological response of paediatric bone sarcomas using FDG PET in comparison to morphological volume measurement and standardized MRI parameters

Purpose

The objective of this study was to evaluate positron emission tomography (PET) using ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) in comparison to volumetry and standardized magnetic resonance imaging (MRI) parameters for the assessment of histological response in paediatric bone sarcoma patients.

Methods

FDG PET and local MRI were performed in 27 paediatric sarcoma patients [Ewing sarcoma family of tumours (EWS), n?=?16; osteosarcoma (OS), n?=?11] prior to and after neoadjuvant chemotherapy before local tumour resection. Several parameters for assessment of response of the primary tumour to therapy by FDG PET and MRI were evaluated and compared with histopathological regression of the resected tumour as defined by Salzer-Kuntschik.

Results

FDG PET significantly discriminated responders from non-responders using the standardized uptake value (SUV) reduction and the absolute post-therapeutic SUV (SUV2) in the entire patient population (?SUV, p?=?0.005; SUV2, p?=?0.011) as well as in the subgroup of OS patients (?SUV, p?=?0.009; SUV2, p?=?0.028), but not in the EWS subgroup. The volume reduction measured by MRI/CT did not significantly discriminate responders from non-responders either in the entire population (p?=?0.170) or in both subgroups (EWS, p?=?0.950; OS, p?=?1.000). The other MRI parameters alone or in combination were unreliable and did not improve the results. Comparing diagnostic parameters of FDG PET and local MRI, metabolic imaging showed high superiority in the subgroup of OS patients, while similar results were observed in the population of EWS.

Conclusion

FDG PET appears to be a useful tool for non-invasive response assessment in the group of OS patients and is superior to MRI. In EWS patients, however, neither FDG PET nor volumetry or standardized MRI criteria enabled a reliable response assessment to be made after neoadjuvant treatment.     

Combined use of 18F-FDG PET/CT and MRI for response monitoring of breast cancer during neoadjuvant chemotherapy

Purpose

To explore the potential complementary value of PET/CT and dynamic contrast-enhanced MRI in predicting pathological response to neoadjuvant chemotherapy (NAC) of breast cancer and the dependency on breast cancer subtype.

Methods

We performed ¹⁸F-FDG PET/CT and MRI examinations before and during NAC. The imaging features evaluated on both examinations included baseline and changes in ¹⁸F-FDG maximum standardized uptake value (SUVmax) on PET/CT, and tumour morphology and contrast uptake kinetics on MRI. The outcome measure was a (near) pathological complete response ((near-)pCR) after surgery. Receiver operating characteristic curves with area under the curve (AUC) were used to evaluate the relationships between patient, tumour and imaging characteristics and tumour responses.

Results

Of 93 patients, 43 achieved a (near-)pCR. The responses varied among the different breast cancer subtypes. On univariate analysis the following variables were significantly associated with (near-)pCR: age (p?=?0.033), breast cancer subtype (p?<?0.001), relative change in SUVmax on PET/CT (p?<?0.001) and relative change in largest tumour diameter on MRI (p?<?0.001). The AUC for the relative reduction in SUVmax on PET/CT was 0.78 (95 % CI 0.68–0.88), and for the relative reduction in tumour diameter at late enhancement on MRI was 0.79 (95 % CI 0.70–0.89). The AUC increased to 0.90 (95 % CI 0.83–0.96) in the final multivariate model with PET/CT, MRI and breast cancer subtype combined (p?=?0.012).

Conclusion

PET/CT and MRI showed comparable value for monitoring response during NAC. Combined use of PET/CT and MRI had complementary potential. Research with more patients is required to further elucidate the dependency on breast cancer subtype.     

Prediction of tumour necrosis fractions using metabolic and volumetric 18F-FDG PET/CT indices, after one course and at the completion of neoadjuvant chemotherapy, in children and young adults with osteosarcoma

Purpose

The utility of combined metabolic and volumetric ¹⁸F-FDG PET/CT indices for predicting tumour necrosis fractions following neoadjuvant chemotherapy has not been extensively studied in osteosarcoma. Furthermore, little is known of the early PET/CT responses after only one chemotherapy course.

Methods

Enrolled in the study were 20 children and young adults with resectable osteosarcoma who had undergone ¹⁸F-FDG PET/CT scans before and after neoadjuvant chemotherapy. Maximum standardized uptake value (mSUV), metabolic tumour volume (MTV), and total lesion glycolysis (TLG) were measured. From among the 20 patients, 14 were prospectively recruited and underwent an additional PET/CT scan after one chemotherapy course. Histopathological necrosis fractions were compared with the above-mentioned PET/CT indices and their ratios.

Results

MTV at the SUV threshold of 2?g/ml was closely correlated with the magnetic resonance image volumes before therapy (r?=?0.91). In the prospective cohort, five patients were classified as good responders and nine as poor responders. All the metabolic indices (mSUV and its ratio) and combined metabolic/volumetric indices (MTV, TLG, and their ratios) except the mSUV ratio determined after therapy showed significant differences between good and poor responders (P <0.05). Differences were also noted for all of these indices determined after one chemotherapy course. Furthermore, most of these indices determined after therapy as well as after one chemotherapy course had good sensitivity, specificity, positive predictive value and negative predictive value with respect to predicting histological response to chemotherapy.

Conclusion

In our osteosarcoma patient population, ¹⁸F-FDG PET/CT indices (either combined metabolic/volumetric or metabolic indices) determined after neoadjuvant chemotherapy were useful in predicting tumour responses. This held true after only one chemotherapy course.     

N staging of lung cancer patients with PET/MRI using a three-segment model attenuation correction algorithm: Initial experience

Objectives

Evaluate the performance of PET/MRI at tissue interfaces with different attenuation values for detecting lymph node (LN) metastases and for accurately measuring maximum standardised uptake values (SUVmax) in lung cancer patients.

Materials and Method

Eleven patients underwent PET/CT and PET/MRI for staging, restaging or follow-up of suspected or known lung cancer. Four experienced readers determined the N stage of the patients for each imaging method in a randomised blinded way. Concerning metastases, SUVmax of FDG-avid LNs were measured in PET/CT and PET/MRI in all patients. A standard of reference was created with a fifth experienced independent reader in combination with a chart review. Results were analysed to determine interobserver agreement, SUVmax correlation between CT and MRI (three-segment model) attenuation correction and diagnostic performance of the two techniques.

Results

Overall interobserver agreement was high (κ?=?0.86) for PET/CT and substantial (κ?=?0.70) for PET/MRI. SUVmax showed strong positive correlation (Spearman’s correlation coefficient = 0.93, P?<?0.001) between the two techniques. Diagnostic performance of PET/MRI was slightly inferior to that of PET/CT, without statistical significance (P?>?0.05).

Conclusions

PET/MRI using three-segment model attenuation correction for LN staging in lung cancer shows a strong parallel to PET/CT in terms of SUVmax, interobserver agreement and diagnostic performance.

Key Points

?F18-FDG PET/MRI shows similar performance to F18-FDG PET/CT in lung cancer N staging. ?PET/MRI has substantial interobserver agreement in N staging. ?A three-segment model attenuation correction is reliable for assessing the mediastinum.     

18F-FDG PET/CT predicts survival in patients with inflammatory breast cancer undergoing neoadjuvant chemotherapy

Purpose

The objective of this study was to evaluate the role of ¹⁸F-FDG PET/CT in predicting overall survival in inflammatory breast cancer patients undergoing neoadjuvant chemotherapy.

Methods

Included in this retrospective study were 53 patients with inflammatory breast cancer who had at least two PET/CT studies including a baseline study before the start of neoadjuvant chemotherapy. Univariate and multivariate analyses were performed to assess the effects on survival of the following factors: tumor maximum standardized uptake value (SUVmax) at baseline, preoperatively and at follow-up, decrease in tumor SUVmax, histological tumor type, grade, estrogen, progesterone, HER2/neu receptor status, and extent of disease at presentation including axillary nodal and distant metastases.

Results

By univariate analysis, survival was significantly associated with decrease in tumor SUVmax and tumor receptor status. Patients with decrease in tumor SUVmax had better survival (P?=?0.02). Patients with a triple-negative tumor (P?=?0.0006), a Her2/neu-negative tumor (P?=?0.038) or an ER-negative tumor (P?=?0.039) had worse survival. Multivariate analysis confirmed decrease in tumor SUVmax and triple-negative receptor status as significant predictors of survival. Every 10 % decrease in tumor SUVmax from baseline translated to a 15 % lower probability of death, and complete resolution of tumor FDG uptake translated to 80 % lower probability of death (P?=?0.014). Patients with a triple-negative tumor had 4.11 times higher probability of death (P?=?0.004).

Conclusion

Decrease in tumor SUVmax is an independent predictor of survival in patients with inflammatory breast cancer undergoing neoadjuvant chemotherapy. Further investigation with prospective studies is warranted to clarify its role in assessing response and altering therapy.     

Prognostic value of volumetric parameters measured by 18F-FDG PET/CT in patients with head and neck squamous cell carcinoma

Purpose

The objective of this study was to investigate the value of metabolic tumour volume (MTV) assessed with ¹⁸F-FDG PET/CT in predicting event-free survival (EFS) and overall survival (OS) in patients with head and neck squamous cell carcinoma (HNSCC), and particularly to compare it with more conventional parameters such as maximum standardized uptake value (SUVmax).

Methods

Patients referred to our department for ¹⁸F-FDG PET/CT for staging of HNSCC were prospectively included between February 2009 and March 2011. Each patient was scanned using a Philips Gemini PET/CT system at 1 h after injection. The MTV was calculated semiautomatically for the primary site using methods based on SUV with various thresholds: 3-D contour around voxels equal to or greater than 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 and 7.0 times SUV, or more than 30 %, 40 % and 50 % of SUVmax. ROC analysis was used to test the statistical significance of the differences among the calculated MTVs. EFS and OS were determined using the Kaplan-Meier method and compared with MTV in univariate and multivariate analyses, including the usual prognostic factors: age, sex, primary site, treatment, SCC histologic grade, AJCC stage, TNM classification, tumour SUVmax and SUVpeak.

Results

The study included 80 consecutive patients (70 men, 10 women; mean age 62.4?±?9.0 years). ROC analysis revealed that pretreatment MTV using a threshold of 5.0 times SUV (MTV5.0) was the best parameter to predict recurrence and death after treatment. In univariate analysis, MTV5.0 >4.9 ml was predictive of poor EFS (p?<?0.0001) and poor OS (p?<?0.0001). In multivariate, MTV5.0 persisted as an independent predictive factor for EFS (p?=?0.011) and OS (p?=?0.010), while SUVmax became nonsignificant (p?=?0.277 for EFS, p?=?0.975 for OS).

Conclusion

Our results suggest that MTV measured by ¹⁸F-FDG PET/CT has independent prognostic value of in patients with HNSCC, stronger than SUVmax.     

The value of 18F-FDG PET/CT in the assessment of active idiopathic retroperitoneal fibrosis

Purpose

The different stages in idiopathic retroperitoneal fibrosis (IRF) are generally assessed by assay of inflammatory markers and analysis of contrast-enhanced CT images of the retroperitoneal mass. We investigated the potential role of ¹⁸F-FDG PET/CT in this clinical setting.

Methods

¹⁸F-FDG uptake was assessed visually and semiquantitatively (using maximum standardized uptake values, SUVmax) in images of the abdominal mass in 22 patients prospectively enrolled from June 2008 to December 2010 who underwent a total of 33 PET/CT studies. The accuracy in discriminating active from inactive disease was calculated assuming as reference a biochemical instrumental evaluation of patients with IRF mostly based on the level of inflammatory indices and contrast enhancement (CE) of the mass at the time of each PET study. In particular, the relationship between SUVmax and CE, the latter calculated from the change in radiodensity (Hounsfield units) between the basal and postcontrast venous portal phases, was evaluated on a three-point scale (0 <20?HU, 1 20–30?HU, 2 ≥30?HU). SUVmax and CE scores were correlated with the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels. The value of PET/CT in assessing the variation of disease activity over time was also investigated by analysing the changes in metabolic volume (MV) of the retroperitoneal lesion between repeat patient studies.

Results

PET/CT accurately discriminated (93.9?%) active from inactive disease. Significant agreement (p?<?0.01) was observed between visual and semiquantitative analysis of ¹⁸F-FDG uptake, and CE score. A significant correlation (p?<?0.01) was found among SUVmax, CRP levels (rho?=?0.54) and ESR (rho?=?0.55). Corresponding variations in MV and CE score were observed in patients with multiple studies (p?<?0.01; rho?=?0.68).

Conclusion

¹⁸F-FDG PET/CT may be considered an alternative imaging method for the assessment of different stages of IRF.     

Evaluation of early response to concomitant chemoradiotherapy by interim 18F-FDG PET/CT imaging in patients with locally advanced oesophageal carcinomas

Purpose

The best way to assess the response to chemoradiotherapy of locally advanced oesophageal carcinomas is not known. We used ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT to evaluate the metabolic response during chemoradiotherapy and tried to correlate this response to survival.

Methods

Patients with biopsy-proven oesophageal carcinoma underwent FDG PET/CT with evaluation of the standardized uptake value (SUV) before any treatment (SUV1) and during chemoradiotherapy after two cycles of 5-fluorouracil (FU)/cisplatin and 20 Gy (SUV2). Metabolic response was defined as 1?(SUV2/SUV1). Surgery was discussed after 40 Gy and three cycles of chemotherapy. Results of interim PET were not considered for the therapeutic decision.

Results

Among 72 patients who underwent a first FDG PET/CT before any treatment, 59 (82 %) could receive the second FDG PET/CT examination. Median survival was 22.2 months with 1-year and 2-year survivals of 70 and 46 %, respectively. Nineteen patients (32 %) underwent surgery. Mean SUV1 and SUV2 were 12.3?±?6.2 and 6?±?4.1, respectively (p?<?0.001). Using a cut-off for metabolic response of 50 %, sensitivity and specificity for survival were 0.7 and 0.58. The 2-year overall survival of good responders was 62 % as compared to 27 % for poor metabolic responders. A multivariate analysis was performed, including T and N stages, surgery, histology and metabolic response: only metabolic response was significantly (p?=?0.009) associated with 2-year survival.

Conclusion

Early evaluation of metabolic response had a great prognostic value and could help identify good responders to chemoradiotherapy.     

Increased FDG uptake in breast cancer is associated with prognostic factors

Purpose

To evaluate the relationship between FDG uptake and prognostic factors of breast cancer such as hormone receptors (estrogen and progesterone), expression of c-erbB-2, axillary lymph node status, tumor histology, grade and size.

Materials and methods

Between May 2009 and February 2011; 79 patients (mean age?±?SD: 52.9?±?13.9?years) with biopsy proven breast cancer underwent F-18 FDG PET/CT scanning for staging. Patients with excisional biopsy or neoadjuvant chemotherapy were excluded from the study. Histological types included were invasive ductal carcinoma (n?=?68), invasive lobular carcinoma (n?=?2), and invasive ductal plus lobular mixed carcinoma (n?=?9). Maximum standardized uptake values (SUVmax) were compared with estrogen (ER) and progesterone receptors (PR), expression of c-erbB-2, as well as tumor grade and tumor size. For the evaluation of relationship between tumor SUVmax values and prognosticators such as hormone receptors, tumor histologic grade, and tumor size, statistical analyses were performed using Student t test, Mann?CWhitney U Test and Pearson correlation coefficient and p values of less than 0.05 were considered to indicate statistically significant differences.

Results

All primary breast neoplasms were detected by PET/CT scanner. The mean SUVmax values and breast cancer tumor sizes ranged from 2.09 to 39.0 and 0.7 to 10?cm, respectively. Tumors with negative ER [(n?=?19); SUVmax median (min?Cmax): 15 (2.09?C39.0)] were associated with higher SUVmax values (p?=?0.01). Tumors with overexpression of C-erbB-2 [(n?=?28); SUVmax median (min?Cmax): 16.0 (5.0-39.0)]; tumor grade 3 [(n?=?25); SUVmax median (min?Cmax): 15 (6.43?C39)]; axillary lymph node involvement [(n?=?60); SUVmax median (min?Cmax): 13.61 (4.0?C39.0)]; tumor histopathology and increased tumor size were associated with higher maximum standardized uptake values. However, PR did not show any relationship with SUVmax values.

Conclusion

In the present report, strong relationships were detected between the negativity of ER, overexpression of c-erbB-2, tumor grade, tumor size, histopathology, axillary lymph node involvement and SUVmax values. Accordingly, we believe that SUVmax values obtained with ¹⁸F-FDG PET/CT may provide some information about tumor biology of breast cancer.     

The combination of FDG PET and dynamic contrast-enhanced MRI improves the prediction of disease-free survival in patients with advanced breast cancer after the first cycle of neoadjuvant chemotherapy

Purpose

The aim of this study was to investigate the potential of FDG PET/CT and MRI in predicting disease-free survival (DFS) after neoadjuvant chemotherapy (NAC) and surgery in patients with advanced breast cancer.

Methods

The analysis included 54 women with advanced breast cancer. All patients received three cycles of NAC, underwent curative surgery, and then received three cycles of additional chemotherapy. Before and after the first cycle of NAC, all patients underwent sequential PET/CT and MRI. All patients were analysed using a diverse range of parameters. including maximal standardized uptake value (SUV), percent change in SUV (ΔSUV), initial slope of the enhancement curve (MRslope), apparent diffusion coefficient (ADC), tumour size, change in MRslope (ΔMRslope), change in ADC (ΔADC), change in tumour size (Δsize) and other clinicopathological parameters]. The relationships between covariates and DFS after surgery were analysed using the Kaplan-Meier method and the multivariate Cox proportional hazards model. Time-dependent receiver operating characteristic curves were used to determine the optimal cut-off values of imaging parameters for DFS.

Results

Of the 54 patients, 13 (24 %) experienced recurrence at a median follow-up of 38 months (range 25 – 45 months). Univariate and multivariate analyses showed that a lesser decline in SUV, a lesser decline in MRslope, a lesser increase in ADC, and ER negativity were significantly associated with a poorer DFS (P?=?0.0006, ΔSUV threshold ?41 %; P?=?0.0016, ΔMRslope threshold ?6 %; P?=?0.011, ΔADC threshold 11 %; and P?=?0.0086, ER status, respectively). Patients with a combination of ΔSUV >?41 % and ΔMRslope >?6 % showed a significantly higher recurrence rate (77.8 %) than the remaining of patients (13.3 %, P?Conclusion Functional parameters of both FDG PET and MRI after the first cycle of NAC are useful for predicting DFS in patients with advanced breast cancer. This approach could lead to an improvement in patient care because ineffective NAC agents could be avoided and more aggressive therapy could be used in high-risk patients.     

The value of 18F-FDG PET/CT for assessing the response to neoadjuvant therapy in locally advanced rectal cancer

Purpose

Neoadjuvant radiochemotherapy (RCT) is an accepted treatment for locally advanced rectal cancer (LARC) that improves surgical outcomes. If a pathological complete response is achieved, conservative surgery can be considered. The objective of our study was to assess the reliability of ¹⁸F-FDG PET/CT for evaluating the response to neoadjuvant RCT in LARC.

Methods

We prospectively studied 41 patients diagnosed with LARC and candidates for neoadjuvant RCT. PET/CT was performed before RCT and again 7?weeks later. A visual and semiquantitative analysis was carried out. The pathological response was classified according to the Mandard tumour regression grade (TRG). We analysed: (a) the relationship between TRG and the result of the posttreatment PET/CT scan, and (b) the correlation between the percentage of pathological response and the percentage decrease in SUVmax according to the response index (RI).

Results

The mean SUVmax of the rectal lesions at diagnosis was 13.6 and after RCT 3.96. The mean RI was 65.32?%. Sensitivity was 88.88?%, specificity 92.86?%, positive predictive value 96?%, negative predictive value 81?%. Of the 41 patients, 8 had TRG I (all negative PET/CT); 6 had TRG II (5 negative, 1 positive PET/CT); 16 had TRG III (13 positive, 3 negative PET/CT); 9 had TRG IV (all positive PET/CT); 2 had TRG V (all positive PET/CT). Of the 14 patients classified as responders (TRG I, II), 13 (92.86?%) had negative PET/CT. Of the 27 patients classified as nonresponders (TRG III?CV), 24 (88.88?%) had positive PET/CT. Differences were statistically significant (p?<?0.0001). The RI in responders was 79.9?% and in nonresponders was 60.3?%. Differences were statistically significant (p?<?0.037).

Conclusion

PET/CT is a reliable technique for assessing response to neoadjuvant RCT in LARC, with a view to considering more conservative surgical treatment. The combination of the visual and semiquantitative analysis increases the diagnostic validity of PET/CT.     

Adrenal-to-liver SUV ratio is the best parameter for differentiation of adrenal metastases from adenomas using 18F-FDG PET/CT

Purpose

To investigate the best standardized uptake value (SUV) index for differentiation of adrenal metastases from adrenocortical adenomas using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT).

Materials and methods

A total of 129 patients (82 males and 47 females; mean age 65.4 years) with extra-adrenal primary malignancies who had known or suspected adrenal lesions underwent FDG PET/CT examinations for detection, staging, re-staging, or recurrence of tumor. Among these patients, 45 adrenal lesions (22 adenomas and 23 metastases) in 41 patients were evaluated. The maximum SUVs for adrenal lesions (adrenal SUVmax) and mean liver and spleen SUVs were recorded, and the ratio of the adrenal SUVmax to the mean liver SUV (adrenal-to-liver SUV ratio) and that of the adrenal SUVmax to the mean spleen SUV (adrenal-to-spleen SUV ratio) were obtained. Diagnostic performances for the adrenal SUVmax, adrenal-to-liver SUV ratio, and adrenal-to-spleen SUV ratio were compared.

Results

The mean adrenal SUVmax, adrenal-to-liver SUV ratio, and adrenal-to-spleen SUV ratio were higher for adrenal metastases (8.4 ± 3.8, 3.0 ± 1.3, and 4.0 ± 1.9, respectively) than for adrenocortical adenomas (2.9 ± 1.0, 0.9 ± 0.3, and 1.3 ± 0.3, respectively) (P < 0.001). The area under the curve was higher for the adrenal-to-liver SUV ratio (0.99) than for the adrenal SUVmax (0.96) and adrenal-to-spleen SUV ratio (0.98). In the differentiation of adrenocortical adenomas and adrenal metastases, an adrenal-to-liver SUV ratio cutoff value of 1.37 yielded a sensitivity of 96 % and specificity of 100 %.

Conclusion

In FDG PET/CT analysis, the adrenal-to-liver SUV ratio had a greater ability to differentiate adrenocortical adenomas and adrenal metastases than did the adrenal SUVmax or adrenal-to-spleen SUV ratio.     

Correlation of high 18F-FDG uptake to clinical, pathological and biological prognostic factors in breast cancer

Purpose

The aim of this study was to determine the impact of the main clinicopathological and biological prognostic factors of breast cancer on ¹⁸F-fluorodeoxyglucose (FDG) uptake. Only women with tumours larger than 20?mm (T2?CT4) were included in order to minimize bias of partial volume effect.

Methods

In this prospective study, 132 consecutive women received FDG PET/CT imaging before starting neoadjuvant chemotherapy. Maximum standardized uptake values (SUV_max) were compared to tumour characteristics as assessed on core biopsy.

Results

There was no influence of T and N stage on SUV. Invasive ductal carcinoma showed higher SUV than lobular carcinoma. However, the highest uptake was found for metaplastic tumours, representing 5% of patients in this series. Several biological features usually considered as bad prognostic factors were associated with an increase in FDG uptake: the median of SUV_max was 9.7 for grade 3 tumours vs 4.8 for the lower grades (p?p?=?0.003); triple-negative tumours (oestrogen and progesterone receptor negative, no overexpression of c-erbB-2) had an SUV of 9.2 vs 5.8 for all others (p = 0005); p53 mutated tumours also had significantly higher SUV (7.8 vs 5.0; p?Conclusion Knowledge of the factors influencing uptake is important when interpreting FDG PET/CT scans. Also, findings that FDG uptake is highest in those patients with poor prognostic features (high grade, hormone receptor negativity, triple negativity, metaplastic tumours) is helpful to determine who are the best candidates for baseline staging.     

Mean and maximum standardized uptake values in [<Superscript>18</Superscript>F]FDG-PET for assessment of histopathological response in oesophageal squamous cell carcinoma or adenocarcinoma after radiochemotherapy

Purpose

To evaluate the potential of [¹⁸F]fluorodeoxyglucose positron emission tomography (FDG-PET) for the assessment of histopathological response and survival after neoadjuvant radiochemotherapy in patients with oesophageal cancer.

Patients and methods

In 2005 and 2006, 55 patients (43 men, 12 women; median age 60 years) with locally advanced oesophageal cancer (cT3-4 Nx M0; 24 with squamous cell carcinoma, 31 with adenocarcinoma) underwent transthoracic en bloc oesophagectomy after completion of treatment with cisplatin, 5-fluorouracil, and radiotherapy ad 36 Gy in a prospective clinical trial. Of the 55 patients, 21 (38%) were classified as histopathological responders (<10% vital residual tumour cells) and 34 (62%) as nonresponders. FDG-PET was performed before (PET 1) and 3–4 weeks after the end (PET 2) of radiochemotherapy with assessment of maximum and average standardized uptake values (SUV) for correlation with histopathological response and survival.

Results

Histopathological responders had a slightly higher baseline SUV than nonresponders (p<0.0001 between PET 1 and PET 2 for responders and nonresponders) and the decrease was more prominent in responders. Except for SUVmax in patients with squamous cell carcinoma neither baseline nor preoperative SUV nor percent SUV reduction correlated significantly with histopathological response. Histopathological responders had a 2-year overall survival of 91?±?9% and nonresponders a survival of 53?±?10% (p?=?0.007).

Conclusion

Our study does not support recent reports that FDG-PET predicts histopathological response and survival in patients with locally advanced oesophageal cancer treated by neoadjuvant radiochemotherapy.

     

The role of FDG PET/CT in patients treated with neoadjuvant chemotherapy for localized bone sarcomas

Purpose

The histological response to neoadjuvant chemotherapy is an important prognostic factor in patients with osteosarcoma (OS) and Ewing sarcoma (EWS). The aim of this study was to assess baseline primary tumour FDG uptake on PET/CT, and serum values of alkaline phosphatase (ALP) and lactate dehydrogenase (LDH), to establish whether these factors are correlated with tumour necrosis and prognosis.

Methods

Patients treated between 2009 and 2014 for localized EWS and OS, who underwent FDG PET/CT as part of their staging work-up, were included. The relationships between primary tumour SUVmax at baseline (SUV1), SUVmax after induction chemotherapy (SUV2), metabolic response calculated as [(SUV1???SUV2)/SUV1)]?×?100, LDH and ALP and tumour response/survival were analysed. A good response (GR) was defined as tumour necrosis >90 % in patients with OS, and grade II-III Picci necrosis (persitence of microscopic foci only or no viable tumor) in patients with Ewing sarcoma.

Results

The study included 77 patients, 45 with EWS and 32 with OS. A good histological response was achieved in 53 % of EWS patients, and 41 % of OS patients. The 3-year event-free survival (EFS) was 57 % in EWS patients and 48 % OS patients. The median SUV1 was 5.6 (range 0?–?17) in EWS patients and 7.9 (range 0?–?24) in OS patients (p?=?0.006). In EWS patients the GR rate was 30 % in those with a high SUV1 (≥6) and 72 % in those with a lower SUV1 (p?=?0.0004), and in OS patients the GR rate was 29 % in those with SUV1 ≥6 and 64 % in those with a lower SUV1 (p?=?0.05). In the univariate analysis the 3-year EFS was significantly better in patients with a low ALP level (59 %) than in those with a high ALP level (22 %, p?=?0.02) and in patients with a low LDH level (62 %) than in those with a high LDH level (37 %, p?=?0.004). In EWS patients the 3-year EFS was 37 % in those with a high SUV1 and 75 % in those with a low SUV1 (p?=?0.004), and in OS patients the 3-year EFS was 32 % in those with a high SUV1 and 66 % in those with a low SUV1 (p?=?0.1). Histology, age and gender were not associated with survival. In the multivariate analysis, SUV1 was the only independent pretreatment prognostic factor to retain statistical significance (p?=?0.017). SUV2 was assessed in 25 EWS patients: the median SUV2 was 1.9 (range 1?–?8). The GR rate was 20 % in patients with a high SUV2, and 67 % in those with a low SUV2 (p?=?0.02). A good metabolic response (SUV reduction of ≥55 %) was associated with a 3-year EFS of 80 % and a poor metabolic response with a 3-year EFS of 20 % (p?=?0.05). In the OS patients the median SUV2 was 2.7 (range 0?–?4.5). Neither SUV2 nor the metabolic response was associated with outcome in OS patients.

Conclusion

FDG PET/CT is a useful and noninvasive tool for identifying patients who are more likely to be resistant to chemotherapy. If this finding is confirmed in a larger series, SUV1, SUV2 and metabolic response could be proposed as factors for stratifying EWS patients to identify those with high-grade localized bone EWS who would benefit from risk-adapted induction chemotherapy.

     

Comparison of the clinical performance of upper abdominal PET/DCE-MRI with and without concurrent respiratory motion correction (MoCo)

Purpose

To compare the clinical performance of upper abdominal PET/DCE-MRI with and without concurrent respiratory motion correction (MoCo).

Methods

MoCo PET/DCE-MRI of the upper abdomen was acquired in 44 consecutive oncologic patients and compared with non-MoCo PET/MRI. SUVmax and MTV of FDG-avid upper abdominal malignant lesions were assessed on MoCo and non-MoCo PET images. Image quality was compared between MoCo DCE-MRI and non-MoCo CE-MRI, and between fused MoCo PET/MRI and fused non-MoCo PET/MRI images.

Results

MoCo PET resulted in higher SUVmax (10.8?±?5.45) than non-MoCo PET (9.62?±?5.42) and lower MTV (35.55?±?141.95 cm³) than non-MoCo PET (38.11?±?198.14 cm³; p?<?0.005 for both). The quality of MoCo DCE-MRI images (4.73?±?0.5) was higher than that of non-MoCo CE-MRI images (4.53±0.71; p?=?0.037). The quality of fused MoCo-PET/MRI images (4.96?±?0.16) was higher than that of fused non-MoCo PET/MRI images (4.39?±?0.66; p?<?0.005).

Conclusion

MoCo PET/MRI provided qualitatively better images than non-MoCo PET/MRI, and upper abdominal malignant lesions demonstrated higher SUVmax and lower MTV on MoCo PET/MRI.

     

Fifteen different 18F-FDG PET/CT qualitative and quantitative parameters investigated as pathological response predictors of locally advanced rectal cancer treated by neoadjuvant chemoradiation therapy

Purpose

The aim of this study was to correlate qualitative visual response and various PET quantification factors with the tumour regression grade (TRG) classification of pathological response to neoadjuvant chemoradiotherapy (CRT) proposed by Mandard.

Methods

Included in this retrospective study were 69 consecutive patients with locally advanced rectal cancer (LARC). FDG PET/CT scans were performed at staging and after CRT (mean 6.7 weeks). Tumour SUVmax and its related arithmetic and percentage decrease (response index, RI) were calculated. Qualitative analysis was performed by visual response assessment (VRA), PERCIST 1.0 and response cut-off classification based on a new definition of residual disease. Metabolic tumour volume (MTV) was calculated using a 40 % SUVmax threshold, and the total lesion glycolysis (TLG) both before and after CRT and their arithmetic and percentage change were also calculated. We split the patients into responders (TRG 1 or 2) and nonresponders (TRG 3–5).

Results

SUVmax MTV and TLG after CRT, RI, ΔMTV% and ΔTLG% parameters were significantly correlated with pathological treatment response (p?<?0.01) with a ROC curve cut-off values of 5.1, 2.1 cm³, 23.4 cm³, 61.8 %, 81.4 % and 94.2 %, respectively. SUVmax after CRT had the highest ROC AUC (0.846), with a sensitivity of 86 % and a specificity of 80 %. VRA and response cut-off classification were also significantly predictive of TRG response (VRA with the best accuracy: sensitivity 86 % and specificity 55 %). In contrast, assessment using PERCIST was not significantly correlated with TRG.

Conclusion

FDG PET/CT can accurately stratify patients with LARC preoperatively, independently of the method chosen to interpret the images. Among many PET parameters, some of which are not immediately obtainable, the most commonly used in clinical practice (SUVmax after CRT and VRA) showed the best accuracy in predicting TRG.     

Variability of average SUV from several hottest voxels is lower than that of SUVmax and SUVpeak

Objectives

To assess variability of the average standard uptake value (SUV) computed by varying the number of hottest voxels within an ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG)-positive lesion. This SUV metric was compared with the maximal SUV (SUV_max: the hottest voxel) and peak SUV (SUV_peak: SUV_max and its 26 neighbouring voxels).

Methods

Twelve lung cancer patients (20 lesions) were analysed using PET dynamic acquisition involving ten successive 2.5-min frames. In each frame and lesion, average SUV obtained from the N?=?5, 10, 15, 20, 25 or 30 hottest voxels (SUV_max–N )_, SUV_max and SUV_peak were assessed. The relative standard deviations (SDrs) from ten frames were calculated for each SUV metric and lesion, yielding the mean relative SD from 20 lesions for each SUV metric (SDr _N , SDr_max and SDr_peak), and hence relative measurement error and repeatability (MEr–R).

Results

For each N, SDr _N was significantly lower than SDr_max and SDr_peak. SDr _N correlated strongly with N: 6.471?×?N ^-0.103 (r?=?0.994; P?<?0.01). MEr–R of SUV_max-30 was 8.94–12.63 % (95 % CL), versus 13.86–19.59 % and 13.41–18.95 % for SUV_max and SUV_peak respectively.

Conclusions

Variability of SUV_max–N is significantly lower than for SUV_max and SUV_peak. Further prospective studies should be performed to determine the optimal total hottest volume, as voxel volume may depend on the PET system.

Key Points

? PET imaging provides functional parameters of ¹⁸ F-FDG-positive lesions, such as SUVmax and SUVpeak. ? Averaging SUV from several hottest voxels (SUVmax- _N ) is a further SUV metric. ? Variability of SUVmax– _N is significantly lower than SUVmax and SUVpeak variability. ? SUVmax– _N should improve SUV accuracy for predicting outcome or assessing treatment response. ? An optimal total hottest volume should be determined through further prospective studies.     

18F-FDG PET/CT imaging versus dynamic contrast-enhanced CT for staging and prognosis of inflammatory breast cancer

Purpose

Inflammatory breast cancer (IBC) is the most aggressive type of breast cancer with a poor prognosis. Locoregional staging is based on dynamic contrast-enhanced (DCE) CT or MRI. The aim of this study was to compare the performances of FDG PET/CT and DCE CT in locoregional staging of IBC and to assess their respective prognostic values.

Methods

The study group comprised 50 women (median age: 51?±?11 years) followed in our institution for IBC who underwent FDG PET/CT and DCE CT scans (median interval 5?±?9 days). CT enhancement parameters were net maximal enhancement, net early enhancement and perfusion.

Results

The PET/CT scans showed intense FDG uptake in all primary tumours. Concordance rate between PET/CT and DCE CT for breast tumour localization was 92 %. No significant correlation was found between SUVmax and CT enhancement parameters in primary tumours (p?>?0.6). PET/CT and DCE CT results were poorly correlated for skin infiltration (kappa?=?0.19). Ipsilateral foci of increased axillary FDG uptake were found in 47 patients (median SUV: 7.9?±?5.4), whereas enlarged axillary lymph nodes were observed on DCE CT in 43 patients. Results for axillary node involvement were fairly well correlated (kappa?=?0.55). Nineteen patients (38 %) were found to be metastatic on PET/CT scan with a significant shorter progression-free survival than patients without distant lesions (p?=?0.01). In the primary tumour, no statistically significant difference was observed between high and moderate tumour FDG uptake on survival, using an SUVmax cut-off of 5 (p?=?0.7 and 0.9), or between high and low tumour enhancement on DCE CT (p?>?0.8).

Conclusion

FDG PET/CT imaging provided additional information concerning locoregional involvement to that provided by DCE CT on and allowed detection of distant metastases in the same whole-body procedure. Tumour FDG uptake or CT enhancement parameters were not correlated and were not found to have any prognostic value.