Evaluation of 18F-2-deoxy-2-fluoro-glucose positron emission tomography for gastric cancer screening in asymptomatic individuals undergoing endoscopy

18F-fluorodeoxyglucose positron emission tomography-computed tomography scan after gastric endoscopy in those who present with non-specific symptoms, is it necessary or not?

Background and Aims:

Retrospectively analyze the sensitivity of ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET-CT) in the diagnosis of gastric malignancy compared with gastric endoscopy in persons with nonspecific symptoms and evaluate the necessity of ¹⁸F-FDG PET-CT scan before surgery.

Materials and Methods:

A total of 53 patients with gastric malignancy proven by surgery and pathology were enrolled in the study. All the patients underwent gastric endoscopy and PET-CT scan before surgery. And the PET-CT images were interpreted by the observers who were blinded to the results of the gastric endoscopy. The sensitivity of gastric endoscopy, ¹⁸F-FDG PET-CT, and serum tumor markers in the diagnosis of gastric malignancy were calculated ultimately.

Results:

Of 53 gastric malignancy patients, five cases were proven to be false-negative detected by gastric endoscopy, and the sensitivity of which was 90.57%. The sensitivity of PET scan alone was 86.79%, which was observed no significant difference to that of gastric endoscopy diagnosis, P = 0.54. While all of the patients had been detected positive on PET-CT images, the sensitivity of which was significantly higher than that of the gastric endoscopy diagnosis or that of the serum tumor markers, P < 0.001. And the FDG uptake was positively correlated with the depth of the cancer invasion into the gastric wall (P < 0.0001) and the degree of lymph nodes infiltration (P = 0.02). It also various from different differentiation degree significantly, P = 0.04.

Conclusions:

¹⁸F-fluorodeoxyglucose PET-CT could detect gastric carcinoma in persons with nonspecific symptoms which showed negative in gastric endoscopy. And it is necessary to be aware of the possibility of gastric malignancy when the result of PET-CT scan is positive.

Limited usefulness of serum carcinoembryonic antigen and carbohydrate antigen 19-9 levels for gastrointestinal and whole-body cancer screening

The diagnostic performance of serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 levels for multiple-organ cancer screening has not been fully elucidated. However, they are widely used for real-world opportunistic screening of multiple-organ cancers. This study aimed to examine the diagnostic performance of these serum markers in multiple-organ cancer screening. Data from asymptomatic individuals subjected to opportunistic cancer screening were analyzed. The diagnostic performance of CEA and CA 19-9 was assessed for (A) upper/lower gastrointestinal cancers and (B) whole-body cancers (including both gastrointestinal and other organ cancers) using the results of upper/lower gastrointestinal endoscopy and whole-body imaging as reference. Data from 12,349 and 7616 screened individuals were used to assess the diagnostic performance of CEA and CA 19-9 for (A) and (B), respectively. For (A), the sensitivity and positive predictive value (PPV) of CEA (cut-off: 5 ng/mL) were 7.8% and 3.7%, respectively; those of CA19-9 (cut-off: 37 U/mL) were 7.4% and 2.7%, respectively. For (B), the sensitivity and PPV of CEA were 6.6% and 4.1%, respectively, and those of CA19-9 were 10.8% and 5.8%, respectively. Considering even multiple cancers, the sensitivity and PPV of CEA and CA 19-9 were low, thus confirming their limited usefulness in multiple-organ cancer screening.

Should 18F-FDG PET/CT Be Routinely Performed in the Clinical Staging of Locally Advanced Gastric Adenocarcinoma?

PURPOSE

The aim of this study was to evaluate F-FDG PET/CT compared with conventional imaging techniques in the clinical management of patients with locally advanced gastric cancer (LAGC).

METHODS

A prospective study between January 2010 and December 2011 in patients with suspected LAGC was conducted in our hospital. F-FDG PET/CT, contrast-enhanced CT (CECT), endoscopic ultrasound, and laparoscopy were performed in all cases. Standard whole-body F-FDG PET/CT images were obtained centered on the stomach at 1 and 2 hours after injection of 4.0 MBq/kg of F-FDG. Findings were confirmed by histopathology or by imaging follow-up in nonoperable patients.

RESULTS

Fifty consecutive patients with confirmed LAGC (20 women, 30 men) with a mean ± SD age of 65.7 ± 12.1 years were included. Using Lauren classification, 24 patients were intestinal subtype, and 26 were diffuse subtype. Thirty-five patients with locoregional lymph node involvement and 22 with distant metastases were confirmed as peritoneal metastases (n = 15), retroperitoneal (n = 2) or mediastinal lymph nodes (n = 1), and liver (n = 3) or bone metastases (n = 1). Patients with signet ring carcinoma showed significantly less F-FDG uptake (P = 0.001). SUVmax correlated with tumor grading (P < 0.05). Standard and delayed F-FDG PET/CT and CECT images identified LAGC in 24, 27, and 28 of 30 patients, respectively. The sensitivity and specificity for F-FDG PET/CT and CECT to detect metastases were 68% and 100% and 64% and 93%, respectively. Contrast-enhanced CT and F-FDG PET/CT diagnosed only 6 of the 15 patients with confirmed peritoneal metastases. The impact in therapeutic management of F-FDG PET/CT and CECT was 24% and 22%, respectively. Kaplan-Meier survival curves for the LGAC showed a significant correlation between SUVmax and overall survival using an SUVmax threshold of less than 3.96 (P = 0.04).

CONCLUSIONS

F-FDG PET/CT should be recommended for staging of LAGC; however, F-FDG PET/CT and CECT cannot replace laparoscopy to rule out peritoneal metastases. Delayed F-FDG PET/CT images show an increase of F-FDG uptake in most cases, improving LAGC detection. The grade of F-FDG uptake represents a significant prognostic tool in this series.

Usefulness of esophagogastroduodenoscopy and 18F-fluorodeoxyglucose positron-emission tomography in detecting synchronous multiple primary cancers with oral cancer

PURPOSE

The purpose of this study is to compare the value of screening for synchronous multiple primary cancers in other organs by esophagogastroduodenoscopy (EGD) or ¹⁸F-fluorodeoxyglucose positron-emission tomography (PET-CT) in patients newly diagnosed with oral cancer.

METHODS

We retrospectively examined consecutive Japanese patients who were diagnosed with oral squamous cell carcinoma (OSCC) and were screened for synchronous multiple primary cancers in other organs by EGD and/or PET-CT between January 2010 and December 2015 at our institution. The study included 190 patients (106 males and 84 females) from 36 to 93 years of age (median age 68.8 years). The patients were screened by EGD, PET-CT, or both before beginning treatment for OSCC.

RESULTS

Of 190 Japanese patients with OSCC, 15 had multiple primary cancers: 13 patients had double cancer and two had triple cancers. The sites of the 17 multiple primary cancers were gastric (6), esophageal (4), and lung (3), and ovarian, colon, liver, and thyroid (1 each). All of the gastric and esophageal cancers were found by EGD and were not detected by PET-CT. For three patients, the detection of multiple cancers affected the treatment modality or order of treatment selected for the OSCC. In two cases, the oral cancer and multiple primary cancer(s) in another organ were resected simultaneously by joint surgical teams.

CONCLUSIONS

PET-CT for oral cancer patients is an effective supporting diagnostic tool. However, the ability of PET-CT has some limitations. Especially for early detection of the upper gastrointestinal cancers, it is necessary to be supplemented by EGD.

Performance of 18-fluoro-2-deoxyglucose positron emission tomography for esophageal cancer screening

AIM

To evaluate the performance of 18-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) for esophageal cancer (EC) screening.

METHODS

We retrospectively analyzed the data of consecutive asymptomatic individuals who underwent FDG-PET and esophagogastroduodenoscopy (EGD) simultaneously for cancer screening at our institution from February 2004 to March 2013. In total, 14790 FDG-PET and EGD procedures performed for 8468 individuals were included in this study, and the performance of FDG-PET for EC screening was assessed by comparing the results of FDG-PET and EGD, considering the latter as the reference.

RESULTS

Thirty-two EC lesions were detected in 28 individuals (31 squamous cell carcinomas and 1 adenocarcinoma). The median tumor size was 12.5 mm, and the depths of the lesions were as follows: Tis (n = 12), T1a (n = 15), and T1b (n = 5). Among the 14790 FDG-PET procedures, 51 examinations (0.3%) showed positive findings in the esophagus; only 1 was a true-positive finding. The screen sensitivity, specificity, positive predictive value, and negative predictive value of FDG-PET for ECs were 3.6% (95%CI: 0.1-18.3), 99.7% (95%CI: 99.6-99.7), 2.0% (95%CI: 0.0-10.4), and 99.8% (95%CI: 99.7-99.9), respectively. Of the 50 FDG-PET false-positive cases, 31 were observed in the lower esophagus, and gastroesophageal reflux disease was observed in 17 of these 31 cases.

CONCLUSION

This study is the first to clarify the FDG-PET performance for EC screening. Based on the low screen sensitivity, FDG-PET is considered to be difficult to use as a screening modality for ECs.

Sensitivity of 2-[18F]fluoro-2-deoxyglucose positron emission tomography for advanced colorectal neoplasms: a large-scale analysis of 7505 asymptomatic screening individuals

BACKGROUND

The sensitivity of 2-[¹⁸F]fluoro-2-deoxyglucose positron emission tomography (FDG-PET) for advanced colorectal neoplasms among healthy subjects is not yet fully understood. The present study aimed to clarify the sensitivity by analyzing large-scale data from an asymptomatic screening population.

METHODS

A total of 7505 asymptomatic screenees who underwent both FDG-PET and colonoscopy at our Cancer Screening Division between February 2004 and March 2013 were analyzed. FDG-PET and colonoscopy were performed on consecutive days, and each examination was interpreted in a blinded fashion. The results of the two examinations were compared for each of the divided six colonic segments, with those from colonoscopy being set as the reference. The relationships between the sensitivity of FDG-PET and clinicopathological features of advanced neoplasms were also evaluated.

RESULTS

Two hundred ninety-one advanced neoplasms, including 24 invasive cancers, were detected in 262 individuals. Thirteen advanced neoplasms (advanced adenomas) were excluded from the analysis because of the coexistence of lesions in the same colonic segment. The sensitivity, specificity, and positive and negative predictive values of FDG-PET for advanced neoplasms were 16.9 % [95 % confidence interval (CI) 12.7-21.8 %], 99.3 % (95 % CI 99.2-99.4 %), 13.5 % (95 % CI 10.1-17.6 %), and 99.4 % (95 % CI 99.3-99.5 %), respectively. The sensitivity was lower for lesions with less advanced histological grade, of smaller size, and flat-type morphology, and for those located in the proximal part of the colon.

CONCLUSIONS

FDG-PET is believed to be difficult to use as a primary screening tool in population-based colorectal cancer screening because of its low sensitivity for advanced neoplasms. Even when it is used in opportunistic cancer screening, the limit of its sensitivity should be considered.

18F-FDG uptake in the stomach on screening PET/CT: value for predicting Helicobacter pylori infection and chronic atrophic gastritis

Background

The aim of this study was to determine the value of ¹⁸F-FDG uptake on screening PET/CT images for the prediction of Helicobacter pylori (H. pylori) infection and chronic atrophic gastritis.

Methods

Among subjects who underwent ¹⁸F-FDG PET/CT for cancer screening from April 2005 to November 2015, PET/CT images were analyzed in 88 subjects who had gastrointestinal fiberscopy within 6 months. The volumes of interest (VOIs) were placed in the fornix, corpus and antrum of the stomach to determine maximal standardized uptake value (SUVmax) and mean SUV (SUVmean). Receiver operating characteristic curve (ROC) analysis was performed to determine the diagnostic performance of SUV indicators in predicting H. pylori infection and chronic atrophic gastritis.

Results

SUV indicators of the stomach were significantly higher in subjects with H. pylori infection than those without (from P < 0.001 to P < 0.05). ROC analysis revealed that SUVmean had the highest performance in predicting H. pylori infection (AUC 0.807) and chronic atrophic gastritis (AUC 0.784). SUVmean exhibited the sensitivity of 86.5 % and the specificity of 70.6 % in predicting H. pylori infection, and the sensitivity of 75.0 % and 78.6 % in predicting chronic atrophic gastritis.

Conclusion

Assessment of ¹⁸F-FDG uptake in the stomach reflecting active inflammation is useful in predicting patients with H. pylori infection and subsequent chronic atrophic gastritis which is closely associated with the risk of gastric neoplasms.

Comparison of FLT-PET/CT and CECT in gastric cancer diagnosis

AIM

To date, no data are available on the use of 18-fluorothymidine positron emission tomography/computed tomography (FLT-PET/CT) for preoperative gastric cancer staging. Herein, we attempt to assess the value of FLT-PET/CT for preoperative gastric cancer staging in comparison with contrast-enhanced computed tomography (CECT).

MATERIALS AND METHODS

In a group of 96 gastric cancer patients, 96 FLT-PET/CT, 56 abdominal cavity CECT, and 51 resective operations were done. All three (FLT-PET/CT, CECT, and resective operation) were done in 29 patients. The results of FLT-PET/CT, CECT, and histopathological examinations were used to assess the ability of FLT-PET/CT and CECT to identify primary tumors, regional nodal metastases, and distant abdominal metastases. Assessment of regional lymph nodes was based on SUVmax in FLT-PET/CT and SAD (short-axis diameter) in CECT.

RESULTS

In the group of 56 patients examined with FLT-PET/CT and CECT, identification of the primary tumor was possible in 56 cases (100%) and in 53 cases (94.6%), respectively, (p = 0.013). Using ROC curve, the sensitivity and specificity of FLT-PET/CT in metastatic regional lymph node assessment were higher than those of CECT (p = 0.0033). FLT-PE/CT enabled identification of a greater number of extraregional abdominal metastases than CECT (n = 56; 19 vs. 15, respectively), but the difference was not statistically significant (p > 0.41).

CONCLUSIONS

The ability of FLT-PET/CT to identify primary tumors is greater than that of CECT, and thus FLT-PET/CT was better in evaluating regional nodal metastases. FLT-PET/CT enabled identification of a greater number of abdominal metastases than CECT, but the difference was not statistically significant.

Is endoscopic ultrasonography still the modality of choice in preoperative staging of gastric cancer?

The treatment option for gastric cancer is usually based on preoperative staging by imaging modalities. Endoscopic ultrasonography (EUS) and computed tomography (CT) have been used as the diagnostic modality of choice in preoperative staging of gastric cancer. Magnetic resonance imaging (MRI) has been employed in several studies, and (¹⁸F) 2-Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) has emerged as a new promising imaging modality. The purpose of this article is to provide summarized information on preoperative staging using EUS, multi-detector row CT (MDCT), MRI and PET for gastric cancer. In T staging, both EUS and MDCT show high accuracy. MRI seemed to have better performance, but the number of MRI studies is limited. FDG-PET is not able to properly evaluate the depth of invasion. In N staging, the diagnostic accuracy of EUS, MDCT and MRI is not sufficient. In preoperative M staging, MDCT and FDG-PET showed similar diagnostic accuracies. FDG-PET/CT fusion could be expected to show better performance in the future. Physicians should keep in mind that each diagnostic modality has advantages and limitations and choose an appropriate diagnostic strategy tailored for each patient.

[Synopsis on clinical practice guideline of gastric cancer in Korea: an evidence-based approach]

Although, gastric cancer is quite common in Korea, the treatment outcome is relatively favorable compared to that of Western countries. However, there is no Korean multidisciplinary guideline for gastric cancer and thus, a guideline adequate for domestic circumstances is required. Experts from related societies developed 22 recommendation statements for the diagnosis (n=9) and treatment (n=13) based on relevant key questions. Evidence levels based on systematic review of literatures were classified as five levels from A to E, and recommendation grades were classified as either strong or weak. The topics of this guideline cover diagnostic modalities (endoscopy, endoscopic ultrasound, radiologic diagnosis), treatment modalities (surgery, therapeutic endoscopy, chemotherapy, radiotherapy) and pathologic evaluation. External review of the guideline was conducted at the finalization phase.

Clinical practice guidelines for gastric cancer in Korea: an evidence-based approach

Although gastric cancer is quite common in Korea, the treatment outcome is relatively favorable compared to those in western countries. However, there are currently no Korean multidisciplinary guidelines for gastric cancer. Experts from related societies developed guidelines de novo to meet Korean circumstances and requirements, including 23 recommendation statements for diagnosis (n=9) and treatment (n=14) based on relevant key questions. The quality of the evidence was rated according to the GRADE evidence evaluation framework: the evidence levels were based on a systematic review of the literature, and the recommendation grades were classified as either strong or weak. The applicability of the guidelines was considered to meet patients' view and preferences in the context of Korea. The topics of the guidelines cover diagnostic modalities (endoscopy, endoscopic ultrasound, and radiologic diagnosis), treatment modalities (surgery, therapeutic endoscopy, chemotherapy, and radiotherapy), and pathologic evaluation. An external review of the guidelines was conducted during the finalization phase.

(18)F-FDG PET/CT surveillance at 3-6 and 12 months for detection of recurrence and second primary cancer in patients with head and neck squamous cell carcinoma

Background:

Early detection of recurrence of head and neck squamous cell carcinoma (HNSCC), which is often obscured by surgical or radiotherapy-induced tissue distortion, is essential for proper patient management.

Methods:

A total of 143 consecutive patients with previously untreated HNSCC were evaluated by whole-body fluorine 18-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) and regular clinical follow-up after curative treatment. The ¹⁸F-FDG PET/CT was performed ∼3–6 and 12 months after treatment and findings suspicious for recurrence or SPC were confirmed using histopathology.

Results:

The sensitivities of 3–6- and 12-month PET/CT scans at patient level were 96% and 93%, respectively, and those of regular clinical follow-up were 11% and 19%, respectively (McNemar test, P<0.001). In patients with no clinical suspicion, PET/CT detected 95% and 91% of recurrent patients at 3–6 and 12 months, respectively. The sensitivity of PET/CT for the identification of SPC was 29% and 80% at 3–6 and 12 months, respectively. A positive interpretation of PET/CT was significantly associated with poor overall survival (log-rank test, P<0.001).

Conclusion:

The ¹⁸F-FDG PET/CT surveillance is beneficial for the detection of recurrence that may be missed by regular follow-up physical and endoscopic examinations of the head and neck area after curative treatment for HNSCC.

Gastric cancers with microsatellite instability exhibit high fluorodeoxyglucose uptake on positron emission tomography

BACKGROUND

Gastric cancers exhibit various degrees of (18)F-fluorodeoxyglucose (FDG) uptakes on positron emission tomography/computed tomography (PET/CT) imaging. The aim of this study was to evaluate whether FDG uptake in gastric cancer varies according to the microsatellite instability (MSI) status.

METHODS

Consecutive gastric cancer patients who underwent PET/CT imaging and MSI analysis were included in the study. The maximum standardized uptake value (SUVmax) of gastric cancer was assessed using PET/CT imaging.

RESULTS

Of 131 gastric cancers, 16 exhibited a high incidence of MSI (MSI-H) and 3 exhibited a low incidence of MSI (MSI-L). In 29 subjects who showed no uptake on PET/CT imaging the gastric cancers were all microsatellite stable (MSS). Gastric cancers with MSI were related to age older than 60 years (p = 0.002), cancer volume larger than 10 cm(3) (p = 0.015), and the presence of FDG uptake on PET/CT imaging (p = 0.001). A higher SUVmax of gastric cancer was linked to the presence of MSI (p < 0.001).

CONCLUSION

The presence of MSI is related to FDG uptake in gastric cancer. Care should be taken with MSS gastric cancers, because they show lower SUVmax on PET/CT imaging than MSI gastric cancers.

Regional PET/CT after water gastric inflation for evaluating loco-regional disease of gastric cancer

OBJECTIVE

We aimed to improve diagnostic accuracy of (18)F-fluoro-2-deoxyglucose (FDG) PET/CT for gastric cancer with water gastric inflation.

MATERIALS AND METHODS

44 gastric cancer patients (M:F=30:14, age ± std=62.1 ± 14.5 y) were enrolled before surgery. Fifty minutes after injection of FDG (0.14 mCi/kg body weight), whole body PET/CT was performed first and then regional PET/CT over gastric area was obtained 80 min post FDG injection after water gastric inflation. Diagnostic accuracies for loco-regional lesions were compared between whole body and regional PET/CT.

RESULTS

48 primary tumors (23 EGC and 25 AGC) and 348 LN stations (61 metastatic and 287 benign) in 44 patients were investigated. Primary tumor sensitivity of whole body PET/CT (50%=24/48) was significantly improved by regional PET/CT (75%=36/48, p<0.005). Sensitivity of whole body PET/CT (24.6%=15/61) for LN metastasis was also significantly improved by regional PET/CT (36.1%=22/61, p<0.01), whereas specificity of whole body PET/CT (99.3%=285/287) was not compromised by regional PET/CT (98.3%=282/287, p>0.05). Higher primary tumor FDG uptake in regional PET/CT indicated shorter progress-free survival (p=0.0003).

CONCLUSION

Diagnostic accuracy of whole body PET/CT for loco-regional disease of gastric cancer could be significantly improved by regional PET/CT after water gastric inflation and prognosis could be effectively predicted by primary tumor FDG uptake in regional PET/CT.

SUVmax/THKmax as a biomarker for distinguishing advanced gastric carcinoma from primary gastric lymphoma

Background

Gastric carcinoma and primary gastric lymphoma (PGL) are the two most common malignancies in stomach. The purpose of this study was to screen and validate a biomarker of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) for distinguishing advanced gastric carcinoma (AGC) from PGL for clinical applications.

Methodology/Principal Findings

We reviewed PET/CT scans collected from January 2008 to April 2012 of 69 AGC and 38 PGL (14 low-grade mucosa-associated lymphoid tissue [MALT], 24 non-MALT aggressive non-Hodgkin lymphoma [ANHL]) with a focus on FDG intensity (maximum standardized uptake value [SUVmax]) of primary lesions and its CT-detected abnormalities, including maximal gastrointestinal wall thickness (THKmax) and mucosal ulcerations. Gastric FDG uptake was found in 69 (100%) patients with AGC and 36 (95%, 12 MALT vs. 24 ANHL)with PGL. The presence of CT-detected abnormalities of AGC and PGL were 97% (67/69) and 89% (12 MALT vs. 22 ANHL), respectively. After controlling for THKmax, SUVmax was higher with ANHL than AGC (17.10±8.08 vs. 9.65±5.24, p<0.05) and MALT (6.20±3.60, p<0.05). THKmax did not differ among MALT, ANHL and AGC. Mucosal ulceration was more common with AGC (n = 9) than PGL (n = 2),but the difference was not statistically significant (p>0.05). Cross-validation analysis showed that for distinguishing ANHL from AGC, the classifier with SUVmax as a feature achieved a correct classification rate of 81% with thresholds 13.40±1.12 and the classifier with SUVmax/THKmax as a feature achieved a correct classification rate of 83% with thresholds 7.51±0.63.

Conclusions/Significance

SUVmax/THKmax may be as a promising biomarker of FDG-PET/CT for distinguishing ANHL from AGC. Structural CT abnormalities alone may not be reliable but can help with PET assessment of gastric malignancies. ¹⁸F-FDG PET/CT have potential for distinguishing AGC from PGL at the individual level.

Predicting the response to chemotherapy in gastric adenocarcinoma: who benefits from neoadjuvant chemotherapy?

Despite a decline in the overall incidence, gastric adenocarcinoma remains the second most common cause of cancer death worldwide and thus a significant global health problem. Even in early-stage locoregional confined disease the 5-year survival rarely exceeds 25-35 %. Randomized trials have demonstrated a benefit from neoadjuvant and perioperative chemotherapy. However the optimal approach in individual patients is not clear and remains controversial. A consistent finding is that patients who have a histopathological response to neoadjuvant therapy are more likely to receive a survival benefit. These clinical data provide a strong argument for the urgent development of methods to predict histopathological response to neoadjuvant therapies for gastric adenocarcinomas. Published data demonstrate that clinico-pathological features (tumour histology and location), imaging through metabolic response by FDG-PET and tissue/molecular biomarkers may all have a predictive value for neoadjuvant therapies. However it is still uncertain from published data whether or not they will be useful for clinical decision making in individual patients. Existing candidate biomarkers need to be properly qualified and validated and novel biomarkers are required and an optimal approach should involve the combination and integration of clinical, imaging, pathological and molecular biomarkers.

Role of (18F) 2-fluoro-2-deoxyglucose positron emission tomography in upper gastrointestinal malignancies

The role of whole-body FDG [(¹⁸F) 2-fluoro-2-deoxyglucose] positron emission tomography (PET) scanning as an imaging modality in the management of patients with malignancy has evolved enormously over the past two decades. FDG-PET has demonstrated significant efficacy in the staging, prognostication and detection of occult metastatic disease in malignancies of the gastrointestinal tract, in addition to assessment of the response to cytotoxic chemotherapy in a more timely manner than has traditionally been possible by more conventional imaging tools. The sensitivity and specificity of FDG-PET for the detection and staging of malignancy depend not only on the site and size of the primary tumor and metastases, but also on histological cell type, reflecting underlying disparities in glucose metabolism. The metabolic response to neo-adjuvant chemotherapy or to chemo-radiotherapy in cancers of the gastro-esophageal junction or stomach has been demonstrated in several prospective studies to correlate significantly with both the histological tumor response to treatment and with consequent improvements in overall survival. This may offer a future paradigm of personalized treatment based on the PET response to chemotherapy. FDG-PET has been less successful in efforts to screen for and detect recurrent upper gastrointestinal malignancies, and in the detection of low volume metastatic peritoneal disease. Efforts to improve the accuracy of PET include the use of novel radiotracers such as (¹⁸F) FLT (3-deoxy-3-fluorothymidine) or ¹¹C-choline, or fusion PET-CT with concurrent high-resolution computed tomography. This review focuses on the role of FDG-PET scanning in staging and response assessment in malignancies of the upper gastrointestinal tract, specifically gastric, esophageal and pancreas carcinoma.

Gastric adenocarcinoma surgery and adjuvant therapy

Gastric adenocarcinoma is one of the most common causes of death worldwide. Surgical resection remains the mainstay of therapy, offering the only chance for complete cure. Resection is based on the principles of obtaining adequate margins, with the extent of lymphadenectomy remaining controversial. Neoadjuvant and adjuvant therapies are used to reduce local recurrence and improve long-term survival. This article reviews the literature and provides a summary of surgical management options and neoadjuvant/adjuvant therapies for gastric adenocarcinoma.

Role of fluoro-2-deoxyglucose positron emission tomography for the detection of gastrointestinal tract lesions in patients with lung cancer

BACKGROUND

  The purpose of this study was to clarify the clinical characteristics of lung cancer patients with abnormal accumulation of fluoro-2-deoxyglucose (FDG) in the gastrointestinal tract imaged by positron emission tomography (PET).

METHODS

  Of 1071 consecutive patients with primary lung cancer who underwent PET from October 2005 through to March 2010, 25 patients (2.3%) showed localized abnormal FDG accumulation in the gastrointestinal tract. We retrospectively compared the location of abnormal accumulation in the gastrointestinal tract, the maximum standardized uptake value in 1 hour, and final clinical diagnosis.

RESULTS

  Of the 25 cases, 12 (48%) were true PET-positive cases (esophageal cancer in one case, gastric cancer in one, colorectal cancer in seven, gastrointestinal stromal tumor in one, and lung cancer metastasis to the stomach and small intestine in one patient each). The 13 cases with false PET-positives were gastric polyp in one, gastritis in four, colon polyp in two, diverticulitis in one, and normal physiological accumulation in five. There was also a significant difference between malignancy and benign intestinal accumulation excluding the stomach (P = 0.002).

CONCLUSION

  PET was useful for screening the gastrointestinal tract (except the stomach) for malignancy in lung cancer patients.

Japanese Gastric Cancer Association Task Force for Research Promotion: clinical utility of ¹⁸F-fluoro-2-deoxyglucose positron emission tomography in gastric cancer. A systematic review of the literature

Since April 2010, the Japanese Public Health Insurance System has covered the costs incurred for performing ¹⁸F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) imaging for patients with advanced gastric cancer. The aim of this review was to evaluate the clinical impact of PET for patients with gastric cancer. A systematic literature search was performed in PubMed/MEDLINE using the keywords "gastric cancer" and "PET" to search for relevant articles published from January 2000 to September 2010. The clinical impact of selected articles was assessed by the authors to evaluate the following: (a) tumor staging, (b) diagnosis for recurrent disease, (c) evaluation of treatment response, and (d) screening for gastric cancer. FDG uptake increases in papillary adenocarcinoma, tubular adenocarcinoma, and solid-type poorly differentiated adenocarcinoma. This uptake is also associated with glucose transporter 1 expression. The sensitivity and specificity of FDG-PET for metastatic lymph node detection were 21-40% and 89-100%, respectively. The sensitivity and specificity for distant metastasis detection were 35-74% and 74-99%, respectively. Treatment response can be detectable at an earlier stage by PET than by computed tomography (CT), because FDG uptake by cancer cells decreases according to the treatment response. In summary, although PET has limitations such as frequent false-negative cases in signet-ring cell carcinoma and non-solid type poorly differentiated carcinoma, it can contribute to the selection of a more appropriate treatment modality by detecting distant metastases and treatment response.

Early detection of recurrence after endoscopic treatment for early gastric cancer

OBJECTIVE

Although there have been many reports regarding clinical outcomes of endoscopic treatment for early gastric cancer (EGC), little is known about detection of recurrence after endoscopic submucosal dissection (ESD). This study aims to clarify the clinical value of serological marker or imaging tools, including conventional CT and PET-CT scans, in detecting recurrent gastric cancer after ESD in Korea.

MATERIAL AND METHODS

From July 2004 to March 2008, 212 patients who had received ESD for EGC were enrolled in the study. For preoperative staging, conventional CT and PET-CT scans were performed in 141 patients, and for detection of recurrence of cancer, conventional CT, PET-CT scans and tumour marker; CEA, CA19-9, AFP were checked in 165 patients.

RESULTS

The local recurrence rate was 4.7% (10/212) during the study period. At 9 months after endoscopic treatment, 3 cases recurred. Four showed recurrence at 12 months, 2 at 18 months and 1 at 24 months. The positive rate was 7.1% (10/141) in conventional CT and 0% (0/24) in PET-CT scans for preoperative staging. Conventional CT and PET-CT scans could not detect local recurrence of cancer during the follow-up period. Tumour markers did not show any significant correlation with recurrence of cancer.

CONCLUSIONS

The study suggests that conventional CT, PET-CT scans and tumour marker have no role in the primary surveillance of early gastric cancer and/or in detecting recurrence after endoscopic treatment. For early diagnosis of recurrence after endoscopic treatment, a biopsy specimen from the endoscopic examination has to be obtained at regular intervals.

Ultrathin endoscopy versus high-resolution endoscopy for diagnosing superficial gastric neoplasia

BACKGROUND

Ultrathin endoscopy (UTE) is an acceptable and cost-effective alternative to EGD with the patient under sedation, although the diagnostic accuracy of UTE is not well established.

OBJECTIVE

To compare the diagnostic accuracy of UTE and high-resolution endoscopy (HRE) for superficial gastric neoplasia.

DESIGN

Prospective comparative study.

SETTING

Academic center.

PATIENTS AND INTERVENTIONS

Patients with or without superficial gastric neoplasia underwent peroral UTE and HRE, back-to-back in a random order while under standard sedation. The procedures were performed by 2 endoscopists who were blinded to the clinical information.

MAIN OUTCOME MEASUREMENTS

The rate of missed lesions and misdiagnosis, sensitivity, and specificity for the diagnosis of gastric neoplasia when using pathology as the reference standard.

RESULTS

In total, 126 lesions (41 superficial gastric neoplasias, 85 nonneoplastic lesions) were recorded in 57 enrolled patients. For the diagnosis of gastric neoplasia, the sensitivity of UTE (58.5%) was significantly (P = .021) lower than that of HRE (78%), and the specificity of UTE (91.8%) was significantly (P = .014) lower than that of HRE (100%). The rate of missed lesions and misdiagnosis of gastric neoplasias when using UTE (41.5%) was significantly (P > .001) higher than that of HRE (22.0%). The corresponding rate of neoplasias at the proximal portion (fornix and corpus) when using UTE (29%) was significantly (P = .002) higher than that of HRE (7.2%), although the rates of neoplasias at the distal portion (angulus and antrum) were comparable for UTE and HRE.

LIMITATION

Small sample numbers in an enriched population.

CONCLUSIONS

The diagnostic accuracy of UTE is significantly lower than that of HRE for superficial gastric neoplasia, and this difference is particularly striking for neoplasias in the proximal stomach. For UTE to be used as an alternative modality, improvements in optical quality and the incorporation of additional procedures, including close-range observations and chromoendoscopy, are required to enhance visualization.

Feasibility of using 18F-FDG PET/CT for pretherapeutic evaluation of advanced gastric cancer

AIM: To investigate the feasibility of using ¹⁸F-FDG PET/CT for pretherapeutic evaluation of advanced gastric cancer.

METHODS: The clinical records of 40 advanced gastric cancer patients who underwent ¹⁸F-FDG PET/CT before treatment were reviewed retrospectively. Of these patients, 14 patients underwent radical gastrectomy, and the other patients underwent chemotherapy or palliative gastrectomy. The lymph nodes were classified into two groups (N₁ + N₂ group and N₃ group) based on anatomic sites. Lymph node metastasis was assessed on group basis. All PET/CT images were interpreted according to visual evaluation and standardized uptake values (SUVs).

RESULTS: The diagnostic sensitivity of ¹⁸F-FDG PET/CT, PET and CT for primary tumors was 97.5%, 65% and 90%, respectively. The sensitivity, specificity, and accuracy of 18F-FDG PET/CT for N₁ + N₂ metastases were 71.4%, 77.8% and 85.7%, respectively, while the sensitivity of PET/CT for N₃ metastases was 100%. PET/CT detected 21 cases of metastases undetected by routine method. Accordingly, the TNM stage of tumors was upgraded in 40% of patients.

CONCLUSION: It is feasible to use ¹⁸F-FDG PET/CT for pretherapeutic evaluation of advanced gastric cancer, and the diagnostic outcomes revealed by PET/CT may have a clinically significant impact on the choice of initial therapy.

Significance of (18)F-2-deoxy-2-fluoro-glucose accumulation in the stomach on positron emission tomography

OBJECTIVE

To explain the accumulation of (18)F-2-deoxy-2-fluoro-glucose ((18)FDG) on positron emission tomography (PET) in the stomach and differences in its pattern, we focus on the accumulation pattern in association with endoscopic findings of the gastric mucosa and Helicobacter pylori (Hp) infection.

METHODS

Of 599 cases undergoing (18)FDG-PET examinations, we retrospectively analyzed the pattern of (18)FDG accumulation in the stomach, findings of upper gastrointestinal endoscopy, and Hp infection. The pattern of (18)FDG accumulation was classified into three groups: localized accumulation only in the fornix (Group A, 32 patients), diffuse accumulation throughout the entire stomach (Group B, 49 patients), and no accumulation (Group C, 191 patients).

RESULTS

Regarding the relation between Hp infection and (18)FDG accumulation, Hp infection was positive in 56.3% of Group A, 73.5% of Group B, and 24.1% of Group C, with significant differences (p < 0.001). Regarding the relation between (18)FDG accumulation and gastric mucosal inflammation, when Groups A and B were compared with Group C, nearly half of the cases in the former groups had papular redness with a significantly higher frequency of redness and erosion. Three cases found to have malignant tumor were limited to the former groups. One MALT lymphoma case was also found in the same group. Accumulation of (18)FDG largely corresponded to mucosal inflammation including superficial gastritis and erosive gastritis, and therefore the main cause of non-specific (18)FDG accumulation was considered to be inflammatory mucosa (mainly redness). The accumulation pattern was not associated with atrophic changes of the gastric mucosa or with Hp infection, but with mucosal inflammatory changes, including redness and erosion localized to the fornix.

CONCLUSIONS

Accumulation of (18)FDG in the stomach suggests a high probability of the presence of inflammatory change in the gastric mucosa forming a background for the development of cancer or malignant lymphoma, and thus requires further endoscopic examinations.

Lymph nodes and gastric cancer

Worldwide, gastric cancer is one of the top three leading causes of cancer mortality, but incidence and presentation vary geographically. Currently, surgery is the only possible cure. Nodal status is an important prognostic indicator for gastric cancer, and despite results of randomized controlled trials, debate continues over the importance of aggressive lymphadenectomy.

FDG-PET has no definite role in preoperative imaging in gastric cancer

BACKGROUND

Gastric cancer is fourth on the incidence list of cancers worldwide with a high disease-related mortality rate. Curation can only be achieved by a radical resection including an adequate lymphadenectomy. However, prognosis remains poor and cancer recurrence rates are high, also due to lymph node metastases. To improve outcome, (neo)adjuvant treatment strategies with chemo- and/or radiotherapy regimes are employed.

AIMS

Accurate staging of gastric cancer at primary diagnosis is essential for adequate treatment. In this non-systematic review the role 18-F-Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) in preoperative staging is investigated. Furthermore, the results of neoadjuvant chemotherapy-induced tumour response monitoring by FDG-PET are discussed.

RESULTS AND CONCLUSION

It is concluded that currently FDG-PET has no role in the primary detection of gastric cancer due to its low sensitivity. FDG-PET shows, however, slightly better results in the evaluation of lymph node metastases in gastric cancer compared to CT and could have therefore a role in the preoperative staging. Improvement in accuracy could be achieved by using PET/CT or other PET tracers than FDG, but these modalities need further investigation. FDG-PET, however, adequately detects therapy responders at an early stage following neoadjuvant chemotherapy.

Research progress in brain function imaging of irritable bowel syndrome

Along with the development of nerve imaging, brain function imaging technique is gradually used in the research of functional gastrointestinal disorders (FGID), and it provides a new method for further investigation of the relationship between brain cortex function, gut function and FGID, as well as the relationship between brain and digestive tract. This review focuses on the major progress in the overseas study of irritable bowel syndrome using positron emission tomography and functional magnetic resonance imaging, the problems and application prospect.