PET imaging in assessing gastrointestinal tumors

Early variation of 18-fluorine-labelled fluorodeoxyglucose PET-derived parameters after chemoradiotherapy as predictors of survival in locally advanced pancreatic carcinoma patients

OBJECTIVE

To investigate if early variation of PET-derived parameters after concomitant chemoradiotherapy (CRT) predicts overall survival (OS), local relapse free survival (LRFS), distant relapse free survival (DRFS) and progression free survival (PFS) in locally advanced pancreatic cancer (LAPC) patients.

METHODS

Fifty-two LAPC patients (median age: 61 years; range: 35-85) with available FDG PET/CT before and after RT (2-6 months, median: 2) were enrolled from May 2005 to June 2015. The predictive value of the percentage variation of mean/maximum standard uptake value (ΔSUVmean/max), metabolic tumour volume (ΔMTV) and total lesion glycolysis (ΔTLG), estimated considering different uptake thresholds (40-50-60%), was investigated between pre- and post-RT PET. The percentage difference between gastrointestinal cancer-associated antigen (ΔGICA) levels measured at the time of PET was also considered. Log-rank test and Cox regression analysis were performed to assess the prognostic value of considered PET-derived parameters on survival outcomes.

RESULTS

The median follow-up was 13 months (range: 4-130). At univariate analysis, ΔTLG50 showed borderline significance in predicting OS (P = 0.05) and was the most significant parameter correlated to LRFS and PFS (P = 0.001). Median LRFS was 4 and 33 months if ΔTLG50 was below or above 35% respectively (P = 0.0003); similarly, median PFS was 3 vs 6 months (P = 0.0009). No significant correlation was found between PET-derived parameters and DRFS, while the ΔGICA was the only borderline significant prognostic value for this endpoint (P = 0.05).

CONCLUSION

PET-derived parameters predict survival in LAPC patients; in particular, ΔTLG50 is the strongest predictor. The combination of these biochemical and imaging biomarkers is promising in identifying patients at higher risk of earlier relapse.

Gastric and colonic metastases from primary lung adenocarcinoma: A case report and review of the literature

Lung cancer is one of the leading causes of cancer-related mortality worldwide. Gastrointestinal metastasis from primary lung cancer is rare. Only a few reports have been published and the majority of described metastatic sites involved the small intestine. In the present study, we report the first case of primary lung adenocarcinoma with both gastric and colonic metastases. We also review the published literature of primary lung cancer with gastrointestinal metastasis.

Predictive value of metabolic 18FDG-PET response on outcomes in patients with locally advanced pancreatic carcinoma treated with definitive concurrent chemoradiotherapy

BACKGROUND

We aimed to study the predictive value of combined 18F-fluoro-deoxy-D-glucose positron emission tomography and computerized tomography (FDG-PET-CT), on outcomes in locally advanced pancreatic carcinoma (LAPC) patients treated with concurrent chemoradiotherapy (C-CRT).

METHODS

Thirty-two unresectable LAPC patients received 50.4 Gy (1.8 Gy/fr) of RT and concurrent 5-FU followed by 4 to 6 cycles of gemcitabine consolidation. Response was evaluated by FDG-PET-CT at post-C-CRT 12-week. Patients were stratified into two groups according to the median difference between pre- and post-treatment maximum standard uptake values (SUVmax) as an indicator of response for comparative analysis.

RESULTS

At a median follow-up of 16.1 months, 16 (50.0%) patients experienced local/regional failures, 6 of which were detected on the first follow-up FDG-PET-CT. There were no marginal or isolated regional failures. Median pre- and post-treatment SUVmax and median difference were 14.5, 3.9, and -63.7%, respectively. Median overall survival (OS), progression-free survival (PFS), and local-regional progression-free survival (LRPFS) were 14.5, 7.3, and 10.3 months, respectively. Median OS, PFS, and LRPFS for those with greater (N = 16) versus lesser (N = 16) SUVmax change were 17.0 versus 9.8 (p = 0.001), 8.4 versus 3.8 (p = 0.005), and 12.3 versus 6.9 months (p = 0.02), respectively. On multivariate analysis, SUVmax difference was predictive of OS, PFS, and LRPFS, independent of existing covariates.

CONCLUSIONS

Significantly higher OS, PFS, and LRPFS in patients with greater SUVmax difference suggest that FDG-PET-CT-based metabolic response assessment is an independent predictor of clinical outcomes in LAPC patients treated with definitive C-CRT.

A metastatic jejunal tumor from squamous cell carcinoma of the lung found in an intestinal perforation

An 85-year-old male with advanced squamous cell carcinoma of the lung, who was diagnosed about 10 years prior to his current presentation, suddenly complained of abdominal pain and underwent an abdominal computed tomography scan, which revealed free air and massive ascites. He was admitted to our hospital for acute peritonitis and emergency surgery was performed. During the surgical procedure, a perforation of the jejunum was diagnosed and repaired. He was diagnosed to have a metastatic tumor originating from a squamous cell carcinoma of the lung. He improved and was transferred to the former hospital on the 27th postoperative day. Jejunal metastasis from squamous cell carcinoma of the lung is rare, and the prognosis of peritonitis due to a perforated intestinal metastasis from lung cancer is poor. There have been 10 reports of jejunal metastasis of squamous cell carcinoma of the lung reported in Japan between 2000 and 2011. Therefore, when patients with advanced lung cancer present with acute abdomen, it is necessary to keep in mind the possibility of a gastrointestinal metastatic tumor.

Surgical resection of metastasis to the pancreas

PURPOSE

Metastasis to the pancreas is rare, and the benefit of resection for pancreatic metastasis is poorly defined. The aim of this study was to review our experiences of the operative management of metastasis to the pancreas.

METHODS

Between 1995 and 2009, 11 patients (8 men and 3 women; median age, 54 years) were admitted to our institution with a metachronously metastatic lesion to the pancreas and later underwent pancreatic resection. The clinical features and outcomes of treatments were examined.

RESULTS

The primary cancers were renal cell carcinoma (RCC, n = 7), carcinoid tumor (n = 2), rectal cancer and leiomyosarcoma. Six patients underwent distal pancreatectosplenectomy, 3 pancreaticoduodenectomy and 2 patients underwent enucleation for small RCC. One patient died of metastatic RCC at 53 months after surgery and ten patients remain alive; four patients without disease at 7 to 69 months postoperatively, and the other six with disease at 11 to 68 months. Median postoperative survival of all patients was 34 months.

CONCLUSION

Patients with a low surgical risk should be considered for pancreatic metastasectomy if curative resection is possible. Primary cancer type, which is associated with survival benefit, would be the best candidate for surgical resection of metastases to the pancreas.

An analysis of the utility of handheld PET probes for the intraoperative localization of malignant tissue

INTRODUCTION

The intraoperative localization of suspicious lesions detected by positron emission tomography (PET) scan remains a challenge. To solve this, two novel probes have been created to accurately detect the (18)F-FDG radiotracer intraoperatively.

METHODS

Nude rats were inoculated with mesothelioma. When PET scans detected 10-mm tumors, animals were dissected and the PET probes analyzed the intraoperative radiotracer uptake of these lesions as tumor to background ratio (TBR).

RESULTS

The 17 suspicious lesions seen on PET scan were localized intraoperatively (by their high TBR) using the PET probes and found malignant on pathology. Interestingly, smaller tumors not visualized on PET scan were detected intraoperatively by their high TBR and found malignant on pathology. Furthermore, using a TBR threshold as low as 2.0, both gamma (sensitivity, 100%; specificity, 80%; positive predictive value (PPV), 96%; and negative predictive value (NPV), 100%) and beta (sensitivity, 100%; specificity, 60%; PPV, 93%; and NPV, 100%) probes reliably detected suspicious lesions on PET scan imaging. They also showed an excellent area under the curve of 0.9 and 0.97 (95% CI of 0.81-0.99 and 0.93-1.0) for gamma and beta probes, respectively, in the receiver operating characteristic analysis for detecting malignancy.

CONCLUSION

This novel tool could be used synergistically with a PET scan imaging to maximize tissue selection intraoperatively.

Imaging a pancreatic carcinoma xenograft model with 11C-acetate: a comparison study with 18F-FDG

PURPOSE

Pancreatic carcinoma is a malignant tumor with poor prognosis and its early detection is still a clinical problem. The aim of this study was to evaluate the efficacy of carbon-11-labeled acetate (11C-acetate)-positron emission tomography (PET) for the detection of pancreatic carcinoma in a BxPC-3 human pancreatic carcinoma xenograft-bearing immunodeficiency BALB/c-nu nude mice model.

METHODS

Whole-body 11C-acetate and fluorine-18-labeled fluorodeoxyglucose (F-FDG) micro-PET imaging were performed weekly on BxPC-3 human pancreatic carcinoma xenograft-bearing BALB/c-nu nude mice from the 2nd week after tumor cell inoculation. Regions of interest method and tumor-to-nontumor ratio (T/N ratio) were used for semiquantitative evaluation. Tumor proliferation was evaluated by immunohistochemistry analysis of proliferating cell nuclear antigen.

RESULTS

Radiotracer accumulation in the tumor xenografts could be detected 1 week earlier in 11C-acetate-PET than that in 18F-FDG-PET. Peak T/N ratio was obtained at the 5th week in 11C-acetate-PET and at the 4th week in 18F-FDG-PET. T/N ratio in 11C-acetate-PET was lower than that in 18F-FDG-PET during the same period. By visual evaluation, tumor xenografts were more easily observed in 11C-acetate-PET than in 18F-FDG-PET in most of the mice. Linear correlation analysis indicated T/N ratios in C-acetate-PET had no significant correlation with those in 18F-FDG-PET. Tumor size, T/N ratio in 11C-acetate-PET, and T/N ratio in 18F-FDG-PET were not found to be significantly correlated with tumor proliferating cell nuclear antigen expression.

CONCLUSION

11C-acetate-PET imaging can be used for the detection of pancreatic carcinoma. In the early stage of tumor growth, 11C-acetate-PET has better detectability than that of 18F-FDG-PET.

Clinical outcome after pulmonary metastasectomy from primary hepatocellular carcinoma: Analysis of prognostic factors

AIM: To review the surgical outcomes in terms of the surgical indications and relevant prognostic factors.

METHODS: Sixteen patients underwent therapeutic lung surgery between March 1999 and May 2006. The observation period was terminated on May 31, 2007. The surgical outcomes and the clinicopathological factors were compared.

RESULTS: There was no mortality or major morbidity encountered in this study. The mean follow-up period after metastasectomy was 26.7 ± 28.2 (range: 1-99 mo), and the median survival time was 20 mo. The 1- and 5-year survival rates were 56% and 26%, respectively. At the end of the follow-up, 1 patient died from hepatic failure without recurrence, 6 died from hepatic failure with a recurrent hepatocellular carcinoma (HCC), and 4 died from recurrent HCC with cachexia. Among several clinical factors, Kaplan-Meier analysis revealed that liver transplantation as a treatment for the primary lesion, grade of cell differentiation, and negative evidence HBV infection were independent predictive factors. On Cox’s proportional hazard model, there were no significant factors affecting survival after pulmonary metastasectomy in patients with HCC.

CONCLUSION: A metastasectomy should be performed before other treatments in selected patients. Although not significant, patients with liver transplantation of a primary HCC survived longer. Liver transplantation might be the most beneficial modality that can offer patients better survival. A multi-institutional and collaborative study would be needed for identifying clinical prognostic factors predicting survival in patients with HCC and lung metastasis.

The multidisciplinary management of gastrointestinal cancer. Biliary tract cancers: from pathogenesis to endoscopic treatment

Cholangiocarcinoma is the second most common hepatobiliary tumour. Even if it is a rare tumour, its incidence is increasing over these last decades, probably due in part to a better knowledge of the disease and to an improvement of the diagnosis. Accurate diagnosis and staging are key steps to determine the appropriate treatment. The only curative treatment of this cancer is surgical resection. To date, no neoadjuvant or adjuvant treatments have ever proved any survival benefit, and are not recommended outside clinical trials. Liver transplantation (with or without neoadjuvant treatment) can be an option for highly selected cases. Unfortunately, these tumours are generally diagnosed at an advanced stage or are unresectable. For most of these patients, palliative therapeutic options exist and are in further development, based on multimodal promising combinations including chemotherapy, targeted agents, radiation, endoscopic stenting and photodynamic treatment.

FDG uptake in PET by bladder hernia simulating inguinal metastasis

A 70-year-old man with past history of hemicolectomy due to colon cancer underwent a follow-up abdominal/pelvic CT scan. CT revealed a right adrenal metastasis and then he underwent FDG-PET/CT study to search for other possible tumor recurrence. In PET images, other than right adrenal gland, there was an unexpected intense FDG uptake at right inguinal region and at first, it was considered to be an inguinal metastasis. However, correlation of PET images to concurrent CT data revealed it to be a bladder herniation. This case provides an example that analysis of PET images without corresponding CT images can lead to an insufficient interpretation or false positive diagnosis. Hence, radiologists should be aware of the importance of a combined analysis of PET and CT data in the interpretation of integrated PET/CT and rare but intriguing conditions, such as bladder herniation, during the evaluation of PET scans in colon cancer patients.

Metastasis of the gastrointestinal tract: FDG-PET imaging

We assess the usefulness of F-18-fluoro-deoxyglucose (FDG) positron emission tomography (PET) in the evaluation of gastrointestinal metastases. Four cases (five lesions) in which metastases from three lung cancers and one malignant fibrous histiocytoma (MFH) of the femur were found in the gastrointestinal tract were reviewed (men/women 3 : 1, age 63-78 years, mean 72 years). The five lesions were duodenal, jejunal metastasis, and two stomach metastases from lung carcinoma, and rectal metastasis from MFH of the femur. FDG-PET was unable to detect small masses, but it was able to detect unforeseen lesions such as gastrointestinal metastases because FDG-PET is a whole-body scan in a single-operation examination. FDG-PET imaging provided valuable information for the diagnosis of gastrointestinal metastasis.

Surgical treatment of metastatic tumors to the pancreas: a single center experience and review of the literature

BACKGROUND

Unlike primary pancreatic carcinoma, metastases to the pancreas are rare, and their resection may be performed as palliative treatment. The aim of this study was to review our experience with the operative management of pancreatic metastases.

MATERIALS AND METHODS

Between January 1994 and December 2004 13 patients (nine women and four men; median age: 59 years; range: 36-79 years) were admitted to our institution with metastatic lesion to the pancreas. The clinical features of the treatment and results were examined.

RESULTS

Primary tumors were renal cell carcinoma (n=5), lobular carcinoma of the breast (n=3), endometrioid carcinoma of the ovary (n=1), colonic adenocarcinoma (n=1), jejunal leiomyosarcoma (n=1), melanoma (n=1), and non-small-cell lung cancer (n=1). The median interval between primary tumor and pancreatic metastases was 36 months (range: 5-192 months). Six patients (46%) were asymptomatic, while the other seven patients presented with jaundice, pain, and duodenal obstruction. Two patients with extrapancreatic disease underwent palliative surgery, and the remaining 11 patients underwent operative procedures that included seven pancreaticoduodenectomy and four distal pancreatectomies with splenectomy. Postoperative mortality was nil, and the morbidity rate was 30%. The two patients who underwent palliative surgery died after 7 and 9 months, respectively. The median survival of the resected patients was 26 months (range: 13-95 months). Five patients died of disease, eight are alive at the time of this report.

CONCLUSION

A trend towards improved survival, even if not statistically significant, was observed in the renal carcinoma patients reported here. Surgical resection can be performed safely in selected patients with isolated metastases to the pancreas, achieving long-term survival as well as good palliation.

Gastro-intestinal metastasis of primary lung carcinoma: clinical presentations and outcome

Symptomatic gastro-intestinal (GI) metastasis in lung carcinomas is extremely rare and only a few case reports have been published. Here we review all of the cases of lung cancer from January 2003 to April 2005 in a tertiary teaching hospital in Taiwan. A total of six patients (1.77%, 6/339) with primary lung cancer demonstrated symptomatic gastro-intestinal metastasis. Three patients had squamous cell carcinoma, one had adenocarcinoma, and two had small cell carcinoma. Three patients with gastric metastasis were diagnosed via gastro-endoscopy while one with cecal involvement was diagnosed via colon fiberscopy. Two patients with small bowel perforation and intussusception were diagnosed via laparotomy. We presented these rare cases and made a review of the literature.

PET/CT detects abdominal wall and port site metastases of colorectal carcinoma

Abdominal wall metastases from colorectal cancer (CRC) may be resected with curative results. Such lesions, often indicators of additional intra-abdominal lesions, may appear in surgical scars, stomas and port site metastases after laparoscope-assisted surgery (LAS). Post-operative changes, primarily surgical scars, alter local physical findings making early detection of small lesions challenging. The purpose of this study was to retrospectively evaluate the contribution of PET/CT to the diagnosis of recurrent colorectal cancer in the post-operative abdominal wall. 120 patients were referred for PET/CT with suspected recurrent CRC based on clinical, radiological or laboratory findings. All underwent whole body PET/CT imaging. 12 of these 120 (10%), were found to have abdominal wall lesions. A total of 16 abdominal wall lesions were detected, located to surgical scars, stomas, drain and laparoscope ports. Additional findings on PET/CT in this group included liver metastases, intra-abdominal lesions and retroperitoneal lymph node involvement. In general, the patients in this small group were young with high grade tumours presenting in advanced stages. In conclusion, PET/CT appears to be a sensitive tool for the diagnosis of abdominal wall recurrence of CRC. The accuracy of localization afforded by the fused functional and anatomic images makes PET/CT a likely tool for diagnosing abdominal wall lesions, including port site metastases of other aetiologies.

PET-Probe: Evaluation of Technical Performance and Clinical Utility of a Handheld High-Energy Gamma Probe in Oncologic Surgery

BACKGROUND

Positron emission tomography (PET) has become an invaluable part of patient evaluation in surgical oncology. PET is less than optimal for detecting lesions <1 cm, and the intraoperative localization of small PET-positive lesions can be challenging as a result of difficulties in surgical exposure. We undertook this investigation to assess the utility of a handheld high-energy gamma probe (PET-Probe) for intraoperative identification of ¹⁸F-deoxyglucose (FDG)-avid tumors.

METHODS

Forty patients underwent a diagnostic whole-body FDG-PET scan for consideration for surgical exploration and resection. Before surgery, all patients received an intravenous injection of 7 to 10 mCi of FDG. At surgery, the PET-Probe was used to determine absolute counts per second at the known tumor site(s) demonstrated by whole-body PET and at adjacent normal tissue (at least 4 cm away from tumor-bearing sites). Tumor-to-background ratios were calculated.

RESULTS

Thirty-two patients (80%) underwent PET-Probe-guided surgery with therapeutic intent in a recurrent or metastatic disease setting. Eight patients underwent surgery for diagnostic exploration. Anatomical locations of the PET-identified lesions were neck and supraclavicular (n = 8), axilla (n = 5), groin and deep iliac (n = 4), trunk and extremity soft tissue (n = 3), abdominal and retroperitoneal (n = 19), and lung (n = 2). PET-Probe detected all PET-positive lesions. The PET-Probe was instrumental in localization of lesions in 15 patients that were not immediately apparent by surgical exploration.

CONCLUSIONS

The PET-Probe identified all lesions demonstrated by PET scanning and, in selected cases, was useful in localizing FDG-avid disease not seen with conventional PET scanning.

Diagnostic accuracy of bone metastases detection in cancer patients: Comparison between bone scintigraphy and whole-body FDG-PET

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has become widely available and an important oncological technique. To evaluate the influence of PET on detection of bone metastasis, we compared the diagnostic accuracy of PET and conventional bone scintigraphy (BS) in a variety of cancer patients.

METHODS

Consecutive ninety-five patients with various cancers, who received both PET and BS within one month, were retrospectively analyzed. A whole-body PET (from face to upper thigh) and a standard whole body BS were performed and these images were interpreted by two experienced nuclear medicine physicians with and without patient information using monitor diagnosis. Each image interpretation was performed according to 8 separate areas (skull, vertebra, upper limbs, sternum and clavicles, scapula, ribs, pelvis, and lower limbs) using a 5-point-scale (0: definitely negative, 1: probably negative, 2: equivocal, 3: probably positive, 4: definitely positive for bone metastasis).

RESULTS

Twenty-one of 95 patients (22.1%) with 43 of 760 areas (5.7%) of bone metastases were finally confirmed. In untreated patients, 12 of 14 bone metastasis positive patients were detected by PET, while 9 of 14 were detected by BS. Three cases showed true positive in PET and false negative in BS due to osteolytic type bone metastases. In untreated cases, PET with and without clinical information showed better sensitivity than BS in patient-based diagnosis. For the purpose of treatment effect evaluation, PET showed better results because of its ability in the evaluation of rapid response of tumor cells to chemotherapy. Out of 10 cases of multiple-area metastases, 9 cases included vertebrae. There was only one solitary lesion located outside of FOV of PET scan in the femur, but with clinical information that was no problem for PET diagnosis.

CONCLUSION

Diagnostic accuracy of bone metastasis was comparable in PET and BS in the present study. In a usual clinical condition, limited FOV (from face to upper thigh) of PET scan may not be a major drawback in the detection of bone metastases because of the relatively low risk of solitary bone metastasis in skull bone and lower limbs.

Novel Imaging Techniques in Melanoma

Cutaneous melanoma is one of the most deadly malignancies. Although it accounts for approximately 4% of all cancer cases, it ac-counts for approximately 79% of skin cancer-related deaths. In the past few years, the nuclear medicine platform used in the management of melanoma has extended to biochemical and structural imaging. In clinical practice, integrated positron emission tomography/CT devices allow anatomic and metabolic characterization of meta-static disease in a single study. Similarly, more accurate localization of sentinel nodes in a 3-D space now is feasible with hybrid single photon emission CT/CT system. In translational research, [18F]fluorodeoxyglucose probes have been designed to optimize the detection of melanoma tumor sites in vivo.

The role of FDG-PET/CT in the detection of recurrent colorectal cancer

PURPOSE

The conventional diagnostic techniques used to assess recurrence of colorectal cancer (CRCR) often yield unspecific findings. Integrated FDG-PET/CT seems to offer promise for the differential diagnosis of benign and malignant lesions. The aim of this study was to compare the value of FDG-PET and PET/CT in the detection of CRCR subsequent to colonic resection or rectal amputation.

METHODS

The population for this retrospective study comprised 84 patients with suspected CRCR. The sensitivity, specificity and accuracy of PET and PET/CT were calculated for (a) intra-abdominal extrahepatic recurrences, (b) extra-abdominal and/or hepatic recurrences and (c) all recurrences, and tumour marker levels were analysed.

RESULTS

The sensitivity, specificity and overall accuracy of PET in detecting intra-abdominal extrahepatic CRCR were 82%, 88% and 86%, respectively, compared with 88%, 94% and 92%, respectively, for PET/CT. The corresponding figures for detection of extra-abdominal and/or hepatic CRCR were 74%, 88% and 85% for PET and 95%, 100% and 99% for PET/CT. Considering the entire population, the sensitivity, specificity and overall accuracy of PET were 80%, 69% and 75%, respectively, compared with 89%, 92% and 90%, respectively, for PET/CT. FDG-PET/CT examination correctly detected 40 out of a total of 45 patients with CRCR. Two of five patients with falsely negative FDG-PET/CT findings had local microscopic recurrences and one had miliary liver metastases. Of 39 patients without CRCR, three showed false positive FDG-PET/CT results. Two of these cases were due to increased accumulation in inflammatory foci in the bowel wall, while one was due to haemorrhaging into the adrenal gland.

CONCLUSION

FDG-PET/CT appears to be a very promising method for distinguishing a viable tumour from fibrous changes, thereby avoiding unnecessary laparotomy.