Characteristics of Primary Papillary Thyroid Carcinoma with False-Negative Findings on Initial 18F-FDG PET/CT

Background

We often observe that uptake of tracer is not detected in the primary cancer focus in patients with histologically proven papillary thyroid carcinoma (PTC) on preoperative ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET/CT). Therefore, we analyzed the clinical and pathologic variables affecting false-negative findings in primary tumors on preoperative ¹⁸F-FDG PET/CT.

Methods

We retrospectively reviewed the medical records of 115 consecutive patients who underwent ¹⁸F-FDG PET/CT for initial evaluation and were diagnosed with PTC by postoperative permanent biopsy. The clinical and pathologic characteristics that influence the ¹⁸F-FDG PET/CT findings in these patients were analyzed with respect to the following variables: age, gender, tumor size, multifocality of the primary tumor, perithyroidal invasion, lymphovascular or capsular invasion, and central lymph node metastasis-based final pathology.

Results

Twenty-six (22.6%) patients had false-negative ¹⁸F-FDG PET/CT findings. In patients with negative ¹⁸F-FDG PET/CT findings, tumor size, and perithyroidal and lymphovascular invasion were significantly less than in patients with positive ¹⁸F-FDG PET/CT findings. Tumors >1 cm in size were correlated with ¹⁸F-FDG PET/CT positivity. On multivariate analysis, perithyroidal invasion (P = 0.026, odds ratio = 7.714) and lymphovascular invasion (P = 0.036, odds ratio = 3.500) were independent factors for ¹⁸F-FDG PET/CT positivity. However, there were no significant differences between ¹⁸F-FDG PET/CT positivity and age, gender, capsular invasion, and central lymph node metastasis based on final pathology.

Conclusions

Tumor size and perithyroidal and lymphovascular invasion of papillary carcinoma can influence ¹⁸F-FDG PET/CT findings. Absence of perithyroidal and lymphovascular invasion were independent variables for false-negative findings on initial ¹⁸F-FDG PET/CT in patients with PTC.     

Utility of 18F-FDG PET/CT for Detecting Neck Metastasis in Patients with Salivary Gland Carcinomas: Preoperative Planning for Necessity and Extent of Neck Dissection

Background:

The precise diagnosis of cervical lymph node metastasis (CLNM) of salivary gland cancer is important to determine the surgical extent and adjuvant therapy. This study assessed the clinical utility of ¹⁸F-FDG PET in identifying CLNM in such patients.

Methods:

Fifty-four patients with intermediate or high-grade salivary gland cancer were preoperatively evaluated with ¹⁸F-FDG PET/CT and CT/MRI. Histopathologic analysis of neck dissection tissues was used as the gold standard for assessing imaging techniques. Tumor and nodal maximum standardized uptake values (SUVmax) were measured for each patient. Univariate and multivariate analyses were used to identify CLNM predictive factors.

Results:

Of the 54 patients, 24 patients (44 %) had CLNM. On a per-patient basis, the sensitivity and specificity of ¹⁸F-FDG PET/CT and CT/MRI were not significantly different (92 vs. 83 %, P = 0.625 and 93 vs. 97 %, P = 1.000, respectively). On a per-level basis, ¹⁸F-FDG PET/CT was significantly more sensitive and accurate than CT/MRI in the ipsilateral neck (96 vs. 54 %, P < 0.001 and 92 vs. 83 %, P < 0.001, respectively). The mean nodal SUVmax values of patients with and without nodal metastasis were 4.9 and 2.1, respectively (P = 0.008). Histologic grade was a significant predictor of CLNM (P = 0.014, odds ratio 14.46, 95 % confidence interval 1.73–120.79).

Conclusions:

¹⁸F-FDG PET/CT imaging and histologic grade are useful for detecting CLNM in patients with salivary gland carcinoma. This finding may guide preoperative planning for the necessity and extent of neck dissection in these patients.     

Acute exacerbation of interstitial lung disease with lung cancer after surgery: evaluation with 2-[18]-fluoro-2-deoxy-d-glucose positron emission tomography

Purpose

Interstitial lung disease (ILD) has been associated with primary lung cancer and an increased risk of postoperative acute exacerbation (AE). The effectiveness of 2-[18]-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron emission tomography (PET) for staging lung cancer is well established. This study investigates the association of FDG uptake on PET in patients with AE of ILD.

Methods

The subjects of this retrospective study were 1309 patients with lung cancer, who underwent pulmonary resection at Shizuoka Cancer Center between September, 2002 and January, 2011. ILD was diagnosed with chest computed tomography in 95 patients, 81 of whom underwent ¹⁸F-FDG PET before surgery. Six patients suffered from AE after surgery (AE group), while the remaining 75 (non-AE group) did not. We investigated the clinico-pathological findings and the results of FDG uptake on PET using the value of the I/M ratio, which is the ratio of the peak of standardized uptake value (SUV) of the ILD area to the mean SUV of the mediastinum.

Results

There was no significant difference in clinico-pathological findings, but a significance difference in the I/M ratio (P = 0.0102).

Conclusion

The FDG uptake in PET may be a predictive factor for AE of ILD in patients who have undergone lung cancer surgery.     

18F-FAMT-PET Is Useful for the Diagnosis of Lymph Node Metastasis in Operable Esophageal Squamous Cell Carcinoma

Background

The role and potential usefulness of positron emission tomography (PET) scanning in certain tumors has been widely investigated in recent years. ¹⁸F-FAMT (L-[3-¹⁸F]-α-methyltyrosine) is an amino acid tracer for PET. This study investigated whether PET/CT with ¹⁸F-FAMT provides additional information for preoperative diagnostic workup of esophageal squamous cell carcinoma compared with that obtained by ¹⁸F-FDG (fluorodeoxyglucose) PET or CT.

Methods

PET/CT studies with ¹⁸F-FAMT and ¹⁸F-FDG were performed as a part of the preoperative workup in 21 patients with histologically confirmed esophageal squamous cell carcinoma.

Results

For the detection of primary esophageal cancer, ¹⁸F-FAMT-PET exhibited a sensitivity of 76.2%, whereas the sensitivity for ¹⁸F-FDG-PET was 90.5% (P = 0.214). ¹⁸F-FAMT uptake in primary tumors showed significant correlation with depth of invasion (P = 0.005), lymph node metastasis (P = 0.045), stage (P = 0.031), and lymphatic invasion (P = 0.029). In the evaluation of individual lymph node groups, ¹⁸F-FAMT-PET exhibited 18.2% sensitivity, 100% specificity, 71.9% accuracy, 100% positive predictive value, and 70.0% negative predictive value, compared with 24.2%, 93.7%, 69.8%, 66.6%, and 70.2%, respectively, for ¹⁸F FDG-PET. CT exhibited 39.4% sensitivity, 85.7% specificity, 69.8% accuracy, 59.1% positive predictive value, and 73.0% negative predictive value. The specificity of ¹⁸F-FAMT-PET is significantly higher than that of ¹⁸F-FDG-PET (P = 0.042) and CT (P = 0.002). ¹⁸F-FAMT-PET did not have any false-positive findings compared to those with ¹⁸F-FDG-PET.

Conclusions

Our findings suggest that the addition of ¹⁸F-FAMT-PET to ¹⁸F-FDG-PET and CT would permit more precise staging of esophageal cancer.     

Early Assessment of Axillary Response with 18F-FDG PET/CT during Neoadjuvant Chemotherapy in Stage II–III Breast Cancer: Implications for Surgical Management of the Axilla

Background

If all initially node-positive patients undergo axillary lymph node dissection (ALND) after neoadjuvant chemotherapy (NAC), overtreatment may occur in patients with complete response. Positron emission tomography–computed tomography (PET/CT) during NAC may predict axillary response and select patients appropriate for less invasive treatment after NAC. We evaluated the value of sequential ¹⁸F fluorodeoxyglucose (FDG) PET/CTs during NAC for axillary response monitoring in stage II–III breast cancer.

Methods

A total of 219 PET/CTs were performed in 80 patients with cytology-proven, node-positive disease at baseline (PET/CT1, n = 80) and twice during NAC (PET/CT2 n = 62, PET/CT3, n = 77). The relative changes in maximum standardized uptake value (SUV_max) of axillary nodes were examined for their ability to assess pathological response. All patients underwent ALND after chemotherapy, and complete axillary response (pCR), defined as absence of isolated tumor cells and of micro- and macrometastases, served as the reference standard.

Results

A total of 32 (40 %) patients experienced axillary pCR. The relative decrease in SUV_max was significantly higher in patients with pCR than in those without, both on PET/CT2 (p < 0.001) and PET/CT3 (p = 0.025). The area under the receiver operating characteristic curve values for PET/CT2 and PET/CT3 were 0.80 (95 % confidence interval 0.68–0.92) and 0.65 (95 % confidence interval 0.52–0.79), respectively. A relative decrease of ≥60 % on PET/CT2 had an excellent specificity (35 of 37, 95 %), a high positive predictive value (12 of 14, 86 %), and a sensitivity of 48 %—that is, it accurately identified histologic pCR in 12 of 25 patients with disease that responded to therapy.

Conclusions

¹⁸F-FDG PET/CT early during NAC is useful for axillary response monitoring in cytology-proven node-positive breast cancer because it identifies pathological response, thus permitting ALND to be spared.     

Role of the standardized uptake value of 18-fluorodeoxyglucose positron emission tomography–computed tomography in detecting the primary tumor and lymph node metastasis in colorectal cancers

Purpose

To assess the role of positron emission tomography–computed tomography (PET–CT) and multidetector-row CT (MD-CT) in detecting the primary lesion and lymph node metastasis in patients with colorectal cancers.

Methods

A collective total of 80 lesions resected from 77 patients were examined pathologically. We analyzed the significance of the standardized uptake value (SUV) and its relationship with the clinicopathologic findings of primary lesions and lymph node metastasis. The detectability of primary lesions and lymph node metastases on PET–CT images was compared with that on MD-CT images.

Results

The detectability of primary lesions was better on PET–CT images than on MD-CT images (p = 0.0023). We observed no significant differences in the SUV with respect to staging, tumor grade, lymphatic or vessel invasion, and macroscopic type; however, primary tumor size analysis revealed that tumors larger than 3 cm had a higher SUV than those smaller than 3 cm. The sensitivity of PET–CT for detecting lymph node metastasis was lower than that of MD-CT, but the specificity of PET–CT was higher than that of MD-CT.

Conclusions

The SUV of primary cancers tends to increase in proportion to tumor size. Although the value of PET–CT in detecting lymph node metastasis is limited, PET -positive lymph nodes can be considered metastatic.     

18-Fluorodeoxyglucose Positron Emission Tomography Predicts Recurrence in Resected Pancreatic Ductal Adenocarcinoma

Background

We aimed to determine whether treatment should be stratified according to 18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) maximum standardized uptake values (SUV_max) in pancreatic ductal adenocarcinoma.

Methods

Patients who underwent preoperative 18F-FDG PET/CT between 2006 and 2014 (n = 138) were stratified into high (≥ 4.85) and low (< 4.85) PET groups. The clinicopathological characteristics and prognostic outcomes were analyzed retrospectively.

Results

The primary tumor SUV_max was positively correlated with preoperative CA19-9 levels (P < 0.001). The high PET group failed to achieve postoperative CA19-9 normalization (P = 0.014). Disease-specific (P < 0.001), recurrence-free (P < 0.001), liver recurrence-free (P < 0.001), and peritoneal recurrence-free (P = 0.020) survivals were significantly shorter in the high PET group. The primary tumor SUV_max was an independent predictive risk factor for liver metastasis (hazard ratio 3.46, 95% confidence interval 1.61–7.87; P = 0.001) and peritoneal recurrence (hazard ratio 3.36, 95% confidence interval 1.18–10.89; P = 0.023).

Conclusions

Surgical resection failed to achieve CA19-9 normalization in the high PET group and distant recurrence was frequent. This suggests the potential for residual cancer at distant sites, even after curative resection. Stronger preoperative systemic chemotherapy is preferred for the high PET group patients.

     

Metabolic Response to Preoperative Chemotherapy Predicts Prognosis for Patients Undergoing Surgical Resection of Colorectal Cancer Metastatic to the Liver

Background

Biological characteristics of colorectal cancer liver metastases (CRCLM) are increasingly recognized as major determinants of patient outcome. The purpose of this study was to evaluate the prognostic value of metabolic response to preoperative chemotherapy as quantified by ¹⁸F-FDG positron emission tomography (PET) for patients undergoing liver resection of CRCLM.

Methods

All patients (n = 80) who had staging PET before liver resection for CRCLM at Austin Health in Melbourne between 2004 and 2011 were included. Thirty-seven patients had PET and CT imaging before and after preoperative chemotherapy. Semiquantitative PET parameters—maximum standardized uptake variable (SUV_max), metabolic tumour volume (MTV), and total glycolytic volume (TGV)—were derived. Metabolic response was determined by the proportional change in PET parameters (?SUV_max, ?MTV, ?TGV). Prognostic scores, CT RECIST response, and tumour regression grading (TRG) were also assessed. Correlation to recurrence-free (RFS) and overall survival (OS) was assessed using Kaplan–Meier survival and multivariate analysis.

Results

Semiquantitative parameters on staging PET before chemotherapy were not predictive of prognosis, whereas all parameters after chemotherapy were prognostic for RFS and OS. Only ?SUV_max was predictive of RFS and OS on multivariate analysis. Patients with metabolically responsive tumours had an OS of 86 % at 3 years vs. 38 % with nonresponsive or progressive tumours (p = 0.003). RECIST and TRG did not predict outcome.

Conclusions

Tumour metabolic response to preoperative chemotherapy as quantified by PET is predictive of prognosis in patients undergoing resection of CRCLM. Assessing metabolic response uniquely characterizes tumour biology, which may allow future optimization of patient and treatment selection.     

Relationship Between <Superscript>18</Superscript>F-fluorodeoxyglucose Accumulation and the <Emphasis Type="Italic">BRAF</Emphasis><Superscript>V600E</Superscript> Mutation in Papillary Thyroid Cancer

Background

To determine whether ¹⁸F-fluoro-2-deoxyglucose (¹⁸F-FDG)-PET/CT is useful for predicting the BRAF ^V600E mutation status of a primary papillary thyroid carcinoma (PTC).

Methods

A retrospective analysis was performed in 108 patients who underwent ¹⁸F-FDG positron emission tomography–computed tomography (PET/CT) for staging before thyroidectomy and BRAF analysis in biopsy-confirmed PTC. The maximum standardized uptake value (SUV_max) of the primary tumor was calculated according to FDG accumulation. Univariate and multivariate analyses were performed to assess the association between the SUV_max and clinicopathological variables.

Results

The BRAF ^V600E mutation was detected in 71 of 108 (65.7%) patients. In all subjects, the tumor size and BRAF ^V600E mutation were independently related to the SUV_max according to multivariate analyses (P = 0.002 and 0.007, respectively). The SUV_max was significantly higher in tumors with the BRAF ^V600E mutation than in tumors with wild-type BRAF (10.24 ± 11.89 versus 4.02 ± 3.86; P = 0.007). In the tumor size >1 cm subgroup, the BRAF ^V600E mutation was the only factor significantly associated with the SUV_max (P = 0.016). A SUV_max cutoff level of 4.9 was determined to be significant for predicting the BRAF ^V600E mutation status (sensitivity 77.4%, specificity 100.0%, area under the curve 0.929; P < 0.0001) according to ROC curve analysis.

Conclusions

The BRAF ^V600E mutation is independently associated with high ¹⁸F-FDG uptake in PTC, especially in those with a tumor size >1 cm.

     

Could 18F-FDG-PET/CT avoid unnecessary thyroidectomies in patients with cytological diagnosis of follicular neoplasm?

Purpose

Preoperative diagnosis of thyroid nodules with “follicular neoplasm” (FN) based on fine-needle aspiration cytology (FNAC) forces thyroidectomy to exclude malignancy. This study explores if ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) provides information enough to prevent unnecessary thyroidectomies in this clinical setting.

Methods

This is a prospective study involving 46 consecutive patients scheduled for thyroidectomy due to follicular neoplasm diagnosis in FNAC (36 follicular, 10 Hürthle cell neoplasms, Bethesda classification) since January 2009 until April 2012. All patients underwent preoperative ¹⁸F-FDG-PET/CT. Abnormal ¹⁸F-FDG thyroid uptake was assessed visually and by measuring the maximum standard uptake value (SUVmax). Results were compared with definitive pathology reports.

Results

Thirteen out of 46 patients (28.3 %) were finally diagnosed with thyroid cancer. Focal uptake correlated with a greater risk of malignancy (p?=?0.009). ¹⁸F-FDG-PET/CT focal uptake showed sensitivity, specificity, positive and negative predictive values and overall accuracy of 92.3, 48.5, 41.4, 94.1 and 60.9 %, respectively. The optimal threshold SUVmax to discriminate malignancy was 4.2 with an area under receiver-operating characteristic curve of 0.76 (95 % confidence interval, 0.60–0.90). Use of ¹⁸F-FDG-PET/CT could reduce by 13–25 % the number of thyroidectomies performed for definitive benign nodules. However, it has demonstrated worse predictive ability in the subgroup of patients with diffuse uptake, oncocytic pattern in FNAC and lesions smaller than 2.

Conclusions

¹⁸F-FDG-PET/CT can play a role in the management of thyroid nodules larger than 2 cm cytologically reported as follicular neoplasm without oncocytic differentiation, allowing the avoidance of a significant number of thyroidectomies for definitive benign lesions.     

18Fluorine-fluorodeoxyglucose positron emission tomography/computed tomography total glycolytic volume in thymic epithelial neoplasms evaluation: a reproducible image biomarker

Introduction

¹⁸Fluorine-fluorodeoxyglucose positron emission tomography/computed tomography is not yet accepted as a standard pretreatment evaluation of thymic epithelial neoplasm (TEN). Statistical correlation between standardized uptake value of tumor/mediastinum ratio and patients’ WHO risk class has been reported. PET metabolic tumor volume (MTV) and total glycolytic volume (TGV) have been reported as additional prognostic imaging biomarkers in several human tumors. Purpose of study was to establish whether MTV and TGV add prognostic information in TEN.

Materials and methods

A retrospective dynamic cohort study of prospectively collected data (2006–2012) on 23 consecutive patients with pathologically proven TEN (no thymic carcinoma) was conducted. All patients underwent chest CT, and PET for staging. SUV T/M ratio, semi-quantitative and volumetric analyses of TEN were calculated. Patients were categorized according to WHO classification (low-risk and high-risk thymomas). Statistical analysis was performed with bootstrap method. Multi-collinearity was established using Pearson correlation coefficient. Cut-off point for TGV was compared using Mantel Cox log rank test.

Results

SUV T/M ratio, MTV, and TGV correlate with low- and high-risk TEN. However, the statistical correlation between TGV and WHO classification (ρ = 0.897) was higher than SUV T/M ratio (ρ = 0.873). Since sample distributions were not uniformly smooth, only one cut-off value was identified: a TGV of 383 served as a cut-off value between low-risk and high-risk TEN.

Conclusion

TGV is a PET reproducible imaging marker in patients with TEN, provides prognostic information, and could be useful in pretreatment stratification of patients. Nevertheless, it needs validation in larger cohort studies.     

18F-FDG-PET/CT to Select Patients with Peritoneal Carcinomatosis for Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

Background

Cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy (HIPEC) is associated with significantly longer survival in patients with peritoneal carcinomatosis (PC). So far, no morphological imaging method has proven to accurately assess the intra-abdominal tumor spread. This study was designed to predict tumor load in patients with PC using dual-modality ¹⁸FDG-PET/CT and to compare the results with those of PET and CT alone by correlating imaging findings with intraoperative staging.

Methods

Twenty-two patients with PC from gastrointestinal (n = 13), ovarian cancer (n = 8), and mesothelioma (n = 1) underwent contrast-enhanced ¹⁸FDG-PET/CT before surgery and HIPEC. In a retrospective analysis PET, CT, and fused PET/CT were separately and blindly reviewed for the extent of peritoneal involvement using the Peritoneal Cancer Index (PCI). Imaging results were correlated with the intraoperative PCI using Pearson’s correlation coefficient and linear regression analysis.

Results

There was a strong correlation between the PCI obtained with PET/CT and the surgical PCI with respect to the total score (r = 0.951) as well as in the regional analysis (small bowel, r = 0.838; other, r = 0.703). The correlation was slightly lower for CT alone (total score, r = 0.919; small bowel, r = 0.754; other, r = 0.666) and significantly lower (p = 0.002) for PET alone (total score, r = 0.793; small bowel, r = 0.553, other, 0.507).

Conclusions

Contrast-enhanced CT is superior compared with PET alone to predict the extent of PC. In our patient group, the combination of both modalities (contrast enhanced PET/CT) yielded the best results and proved to be a useful tool for selecting candidates for peritonectomy and HIPEC.     

18F-fluorocholine PET/CT compared with extended pelvic lymph node dissection in high-risk prostate cancer

Purpose

To compare ¹⁸F-fluorocholine positron-emission tomography/computed tomography (PET/CT) with extended pelvic lymph node dissection (ePLND) for the detection of lymph node metastases in a large cohort of patients with high-risk prostate cancer.

Materials and methods

Patients with prostate-specific antigen levels between 20 and 99 ng/mL and/or Gleason score 8–10 cancers, planned for treatment with curative intent following a negative or inconclusive standard bone scan, were investigated with ¹⁸F-fluorocholine PET/CT followed by an ePLND. None of the patients received hormonal therapy prior to these staging procedures. Results for PET/CT were compared on a per-patient basis with histopathology from ePLND. Sensitivity, specificity, positive and negative predictive values were calculated.

Results

PET/CT detected a total of 76 suspected lymph node metastases and four suspected bone metastases in 33 (29 %) of the 112 included patients. Of these, 35 suspected lymph node metastases, only within the anatomical template area of an ePLND, were found in 21 of the patients. Histopathology of the ePLND specimens detected 117 lymph node metastases in 48 (43 %) of the 112 patients. Per-patient sensitivity, specificity, positive and negative predictive values for ¹⁸F-fluorocholine PET/CT for lymph node metastases within the ePLND template were 0.33, 0.92, 0.76 and 0.65, respectively. Only 11 patients had lymph nodes larger than 10 mm that would have been reported by CT alone.

Conclusions

¹⁸F-fluorocholine PET/CT detects lymph node metastases in a significant proportion of patients with high-risk prostate cancer with a high specificity, but low sensitivity.     

Prognostic Impact of [18F] FDG-PET in Operable Breast Cancer Treated with Neoadjuvant Chemotherapy

Background

This study aimed to evaluate the usefulness of serial [¹⁸F] 2-fluoro-2-deoxy-d-glucose–positron emission tomography ([¹⁸F] FDG-PET) in potentially operable breast cancer with neoadjuvant chemotherapy.

Methods

Serial positron emission tomography was undertaken in 66 breast cancer patients who comprised a subset of the population in a phase III randomized neoadjuvant trial at National Cancer Center, Korea. We assessed the peak standardized uptake value (SUVp) in the primary tumor and axillary nodes before and after neoadjuvant chemotherapy and calculated the reduction rate (RR) of the SUVp. By means of a receiver operating characteristic curve, we identified an optimal cutoff value for the RR for predicting the pathologic response and evaluated the prognostic power of this cutoff value.

Results

Ten patients (15.2%) experienced a pathologic complete response (pCR) in the primary tumor, and 19 patients (28.8%) experienced a pCR in the axillary nodes. The mean RR of the SUVp in primary tumors was 70.3% ± 28.7%, and this value was significantly different by the pathological response (89.2% ± 11.1% in pCR vs. 66.9% ± 29.6% in non-pCR, P < .001). When 84.8% of the RR was used as a cutoff value for the pCR, sensitivity and specificity was 70.0% and 69.6%, respectively. Ten patients (15.2%) developed recurrent disease at a median follow-up period of 61.5 (range, 13.5–71.8) months. In a univariate analysis, the 5-year disease-free survival (DFS) was correlated with the clinical T stage (91.1% in T1/2 vs. 71.4% in T3/4, P = .02), HER-2 status (77.8% in positive vs. 96.9% in negative, P = .03), and the 84.8% RR of the SUVp in the primary tumor (95.8% vs. 78.5%, P = .04). HER-2 positivity was a significant independent prognosticator in the multivariate analysis (hazard ratio 8.73, 95% confidence interval 1.03–73.84, P = .04). The presence of a pCR in the primary tumor or nodes was not a prognostic factor in this subset of patients. The RR of the SUVp in the axillary nodes was not correlated with the nodal pCR and DFS.

Conclusions

The RR of the SUVp in the primary tumor was correlated with the pathologic response and DFS. This study suggests the possible prognostic value of the RR in positron emission tomography by neoadjuvant chemotherapy.     

Clinical Significance of Incidental Colonic 18F-FDG Uptake on PET/CT Images in Patients with Gastric Adenocarcinoma

Background and Objectives

We assessed the ability of positron emission tomography?Ccomputed tomography (PET/CT) to detect synchronous colonic pathology and determined the significance of 18F-fluorodeoxyglucose (¹⁸F-FDG) activity in the colon of gastric cancer patients.

Methods

A total of 239 gastric cancer patients who underwent PET/CT and colonoscopy preoperatively were included. FDG uptake patterns on PET/CT were classified as (1) group A, focal; (2) group B, diffuse; and (3) group C, no uptake. The PET/CT findings were compared with the results of concurrent colonoscopy.

Results

In group A, a total of 123 polyps of >0?mm were observed. Of these, nine polyps were colonic adenocarcinomas and six were high-grade dysplasia. The incidence of colonic adenocarcinomas was significantly higher in group A than in the other two groups (p?=?0.037). There was a significant correlation between SUVmax values and incidence of colonic polyps of >10?mm (r?=?0.471, p?=?0.04). The distribution pattern of SUVmax in polyps with adenoma (>10?mm) was less homogenous than in polyps (>10?mm) with adenocarcinoma.

Conclusions

The focal colonic FDG uptake in PET/CT requires colonoscopic confirmation. The suspicion of colonic malignancy increased in the presence of polyps >10?mm that showed a positive correlation with the SUVmax.     

The Added Diagnostic Value of <Superscript>18</Superscript>F-Fluorodihydroxyphenylalanine PET/CT in the Preoperative Work-Up of Small Bowel Neuroendocrine Tumors

Background

The precise localization of the primary tumor and/or the identification of multiple primary tumors improves the preoperative work-up in patients with small bowel (SB) neuroendocrine tumor (NET). The present study assesses the diagnostic value of ¹⁸F-fluorodihydroxyphenylalanine (¹⁸F-FDOPA) positron emission tomography/computed tomography (PET/CT) during the preoperative wok-up of SB NETs.

Methods

Between January 2010 and June 2017, all consecutive patients with SB NETs undergoing preoperative ¹⁸F-FDOPA PET/CT and successive resection were analyzed. Preoperative work-up included computed tomography (CT), somatostatin receptor scintigraphy (SRS), and ¹⁸F-FDOPA PET/CT. Sensitivity and accuracy ratio for primary and multiple tumor detection were compared with data from surgery and pathology.

Results

There were 17 consecutive patients with SB NETs undergoing surgery. Nine patients (53%) had multiple tumors, 15 (88%) metastatic lymph nodes, 3 (18%) peritoneal carcinomatosis, and 9 patients (53%) liver metastases. A total of 70 SB NETs were found by pathology. Surgery identified the primary in 17/17 (100%) patients and recognized seven of 9 patients (78%) with multiple synchronous SB. Preoperatively, ¹⁸F-FDOPA PET/CT displayed a statistically significant higher sensitivity for primary tumor localization (100 vs. 23.5 vs. 29.5%) and multiple tumor detection (78 vs. 22 vs. 11%) over SRS and CT. Compared with pathology, ¹⁸F-FDOPA PET/CT displayed the highest accuracy ratio for number of tumor detected over CT and SRS (2.0?±?2.2 vs. 0.4?±?0.7 vs. 0.6?±?1.5, p?=?0.0003).

Conclusion

¹⁸F-FDOPA PET/CT significantly increased the sensitivity and accuracy for primary and multiple SB NET identification. ¹⁸F-FDOPA PET/CT should be included systematically in the preoperative work-up of SB NET.

     

Preoperative Consolidation-to-Tumor Ratio and SUVmax Stratify the Risk of Recurrence in Patients Undergoing Limited Resection for Lung Adenocarcinoma ≤2 cm

Purpose

Limited resection is an increasingly utilized option for treatment of clinical stage IA lung adenocarcinoma (ADC) ≤2 cm (T1aN0M0), yet there are no validated predictive factors for postoperative recurrence. We investigated the prognostic value of preoperative consolidation/tumor (C/T) ratio [on computed tomography (CT) scan] and maximum standardized uptake value (SUVmax) on ¹⁸F-fluorodeoxyglucose-positron emission tomography (PET) scan.

Methods

We retrospectively reviewed 962 consecutive patients who underwent limited resection for lung cancer at Memorial Sloan-Kettering between 2000 and 2008. Patients with available CT and PET scans were included in the analysis. C/T ratio of 25 % (in accordance with the Japan Clinical Oncology Group 0201) and SUVmax of 2.2 (cohort median) were used as cutoffs. Cumulative incidence of recurrence (CIR) was assessed.

Results

A total of 181 patients met the study inclusion criteria. Patients with a low C/T ratio (n = 15) had a significantly lower 5-year recurrence rate compared with patients with a high C/T ratio (n = 166) (5-year CIR, 0 vs. 33 %; p = 0.015), as did patients with low SUVmax (n = 86) compared with patients with high SUVmax (n = 95; 5-year CIR, 18 vs. 40 %; p = 0.002). Furthermore, within the high C/T ratio group, SUVmax further stratified risk of recurrence [5-year CIR, 22 % (low) vs. 40 % (high); p = 0.018].

Conclusions

With the expected increase in diagnoses of small lung ADC as a result of more widespread use of CT screening, C/T ratio and SUVmax are widely available markers that can be used to stratify the risk of recurrence among cT1aN0M0 patients after limited resection.     

Bedeutung der PET für die Chirurgie des gastrointestinalen Stromatumors

Background

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the digestive tract. The GIST differ substantially from gastrointestinal carcinomas regarding tumor biology, treatment strategies and indications for surgery. Every surgeon involved in the treatment of GIST should be acquainted with these aspects.

Objectives

The aims of this article are to discuss the value of positron emission tomography (PET) in the surgical treatment of patients with GIST and to provide an outlook on the development of molecular tracers specifically tailored for GIST.

Results

PET is an invaluable decision aid in the multimodal therapy of GIST and particularly for deciding on surgical indications. Specific scenarios in which PET is used are primary staging monitoring during neoadjuvant therapy and staging and response assessment in the metastatic setting. The routinely used tracer is 18F-fluorodeoxyglucose (18F-FDG) and uptake reliably correlates with the metabolism of GIST lesions. Compared to computed tomography and magnetic resonance imaging (CT/MRI), 18F-FDG-PET often allows a more timely and accurate response assessment. GIST-specific molecular tracers, which could provide a direct prognosis regarding response and development of resistance to treatment, are currently in preclinical development. However, pharmacokinetic and immunological issues still need to be resolved. A distant aim is the development of “theranostics”, i.e. substances which serve both diagnostic and therapeutic purposes.

Discussion

PET has an established value in the multimodal treatment of GIST and is particularly useful for deciding on surgical indications.     

A Systematic Review of the Predictive Value of 18FDG-PET in Esophageal and Esophagogastric Junction Cancer After Neoadjuvant Chemoradiation on the Survival Outcome Stratification

Purpose

We studied the predictive value of [¹⁸?F]fluorodeoxyglucose-positron emission tomography (¹⁸FDG-PET) for assessing disease-free (DFS) and overall survival (OS) in esophageal and esophagogastric junction cancer.

Materials and methods

A literature search (PUBMED/MEDLINE, EMBASE, Cochrane) was performed to identify full papers with ¹⁸FDG-PET and survival data, using indexing terms and free text words. Studies with >10 patients with locally advanced esophageal cancer, presenting sequential or at least one post-adjuvant treatment ¹⁸FDG-PET data and Kaplan–Meier survival curves with >6 months median follow-up period were included. We performed a meta-analysis for DFS and OS using the hazard ratio (HRs) as outcome measure. Sources of heterogeneity study were also explored.

Results

We identified 26 eligible studies including a total of 1,544 patients (average age 62 years, 82 % males). The TNM distribution was as follows: stage I 7 %, II 24 %, III 53 % and IV 15 %. The pooled HRs for complete metabolic response versus no response were 0.51 for OS (95 % CI, 0.4–0.64; P?<?0.00001) and 0.47 for DFS (95 % CI, 0.38–0.57; P?<?0.00001), respectively. No statistical heterogeneity was present. To explore sources of clinical heterogeneity, we also realised subgroup and regression analyses. Taken into account the moderate correlation between OS and DFS (ρ?=?0.54), we used joint bivariate random regression model. These analyses did not show a statistically significant impact of study characteristics and PET modalities on the pooled outcome estimates.

Conclusion

Despite methodological and clinical heterogeneity, metabolic response on ¹⁸FDG-PET is a significant predictor of long-term survival data.     

Incidental Thyroid Carcinoma by FDG-PET/CT: A Study of Clinicopathological Characteristics

Background

The rising incidence of incidental thyroid carcinoma (ITC) detected during fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) scanning poses a challenge to clinicians. The present study aims to critically evaluate the clinicopathological characteristics of ITC detected by FDG-PET/CT.

Methods

Among the 557 patients managed at our institution, 40 (7.2%) patients were identified as having ITC. Of these, 22 patients had their tumor detected by FDG-PET/CT (PET group) and 11 by ultrasonography (USG group). Additional bedside ultrasonography ± fine-needle aspiration (FNA) was done in all patients at their clinic visit. The clinicopathological characteristics were compared between the PET and USG groups.

Results

The PET group had significantly more patients with history of nonthyroidal malignancy (P < 0.001). Papillary carcinoma was the most common histological type in both groups. Despite having similar histological and prognostic features including tumor size, tumor multifocality, capsular invasion, extrathyroidal extension, and lymph node metastases, tumor bilaterality (or presence of contralateral tumor focus) was significantly more frequent in the PET than the USG group (P = 0.04). The tumors were also more advanced by the tumor–node–metastasis (TNM) staging system in the PET group (P = 0.021). None of the contralateral tumor foci were evident preoperatively. One patient in the USG group developed metastatic thyroid carcinoma in neck lymph nodes 28 months after thyroid resection.

Conclusion

ITC by FDG-PET/CT had higher incidence of tumor bilaterality than those detected by ultrasonography. Total thyroidectomy should be considered for ITC detected by FDG-PET/CT even for tumor size <10 mm.