Joint Program in Nuclear Medicine

PET Imaging Pancreatic Carcinoma

Hossein Jadvar, MD, PhD
Alan J. Fischman, MD, PhD

February 2, 1999

Presentation

A 66 year old male initially presented with painless jaundice. After diagnosis, he underwent abdominal surgery, radiation and chemotherapy. One year later, he presented with upper GI bleed and was admitted to the hospital. While in hospital, abdominal CT and PET imaging were performed.

Imaging Technique

Abdominal CT: Axial images after oral and intravenous contrasts.
FDG PET: Attenuation-corrected imaging (Scanditronix PC-4096) was performed 45 minutes after intravenous injection of 11 mCi FDG.

Imaging Findings

Abdominal CT

Coronal FDG PET

Abdominal CT: The axial image of the abdomen shows heterogeneous abnormal soft tissue (shown by arrow) in the surgical bed region shown here at the level of splenic venous confluence to the portal vein. Post-therapy changes cannot be distinguished from recurrent tumor. Low attenuation region in the right hepatic lobe corresponds to a cyst.
FDG PET: The coronal image of the abdomen shows a small area of intense tracer accumulation in upper mid abdomen (shown by arrow) in the surgical bed region, highly suspicious for recurrent tumor. Note the photopenic region in the peripheral right hepatic lobe representing the cyst.

Differential Diagnosis

pancreatic carcinoma
- ductal - most common
- other rare tumors
  - adenosquamous carcinoma
  - cystadenocarcinoma
  - acinar cell carcinoma
  - anaplastic carcinoma
cholangioadenocarcinoma
carcinoma of the Ampula of Vater
duodenal cancer
lymphoma
sarcoma
metastatic tumor
infectious or non-infectious pancreatitis (including chronic pancreatitis)

Diagnosis

The patient underwent multiple endoscopies for coagulation of ulcers. The clinical course, however, became complicated with the development of pneumonia and peritonitis that resulted in death. A limited autopsy was performed. Pancreatic ductal adenocarcinoma was noted at the pancreatico-jejunostomy anastomosis corresponding to the PET and CT soft tissue abnormalities.

Discussion

Pancreatic carcinoma has a poor prognosis. Many patients present late in the course of disease with nonspecific signs and symptoms. The more common clinical features include weight loss, anorexia, and painless jaundice. Serum tumor marker CA19-9 is insensitive and nonspecific for screening.

Diagnostic imaging techniques for detection of pancreatic cancer include sonography, endoscopic retrograde cholangiopancreaticography (ERCP), CT, MRI, and thallium-201 scintigraphy. However, these techniques may be equivocal, cannot accurately differentiate cancer from chronic pancreatitis, as well as post-therapy changes from recurrent or residual disease in patients who had undergone Whipple procedure and/or chemoradiation therapy. FDG PET has been shown by several investigators to provide an accurate imaging tool for evaluating patients with known or suspected pancreatic carcinoma and affects the clinical management [1-9].

Reske et al. showed that pancreatic carcinoma displays a higher glucose transporter 1 (Glut-1) to glucose transporter 4 (Glut-4) ratio in comparison to chronic mass-forming pancreatitis. The overexpression of Glut-1 gene or decreased degradation of Glut-1 mRNA may then explain the enhanced glycolytic metabolism in pancreatic cancer. These same authors also showed that the mean standardized uptake value (SUV) was significantly higher in cancer (3) than in chronic pancreatitis (1.3) [4]. Friess et al. also reported similar results for SUV (3 for cancer vs. 0.9 for chronic pancreatitis) with an overall sensitivity of 94% and specificity of 88% for detecting malignancy [2]. In another study comparing PET and CT in detecting cancer in 73 patients with suspected pancreatic malignancy, PET (with cutoff SUV of 1.53) had higher sensitivity (93% PET vs. 80% CT) and specificity (93% PET vs. 74% CT) [5].

Ho et al. also reported similar findings and demonstrated the usefulness of PET in assessing indeterminate pancreatic masses on CT [9]. Inokuma et al. showed that PET was more accurate than CT and US in detecting malignancy in 46 patients with suspected pancreatic cancer [8]. Two false positive PET findings were related to chronic active pancreatitis and serous cystadenoma. In a recent prospective study reported by Keogan et al., PET had a sensitivity of 88% and a specificity of 83% in detecting cancer in 37 patients with suspected malignancy based on CT and ERCP findings [7]. In summary, FDG PET is useful in staging and determination of resectability of pancreatic cancer at the time of initial diagnosis as well as in re-evaluation of patients after therapy and in differentiating malignancy from chronic pancreatitis.

References

1. Hawkins R. Pancreatic tumors: imaging with PET. Radiology 1995; 95:320-322.

2. Friess H, et al. Diagnosis of pancreatic cancer by 2[18F]-fluoro-2-deoxy-D-glucose positron emission tomography. Gut 1995; 365:771-777.

3. Zimny M, et al. Fluorine-18 fluorodeoxyglucose positron emission tomography in the differential diagnosis of pancreatic carcinoma: a report of 106 cases. Eur J Nucl Med 1997; 24(6):678-682.

4. Reske SN, et al. Overexpression of glucose transporter 1 and increased FDG uptake in pancreatic carcinoma. J Nucl Med 1997; 38(9):1344-1348.

5. Stollfuss JC, et al. 2-(fluorine-18)-fluoro-2-deoxy-D-glucose PET in detection of pancreatic cancer: value of quantitative image interpretation. Radiology 1995; 195(2):339-344.

6. Inokuma T, et al. Value of fluorine-18-flurodeoxyglucose and thallium-201 in the detection of pancreatic cancer. J Nucl Med 1995; 36(2):229-235.

7. Keogan MT, et al. Diagnosis of pancreatic carcinoma: role of FDG PET. AJR 1998; 171(6):1565-1570.

8. Inokuma T, et al. Evaluation of pancreatic tumors with positron emission tomography and F-18 fluorodeoxyglucose: comparison with CT and US. Radiology 1995; 195:345-352.

9. Ho CL, et al. FDG-PET evaluation of indeterminate pancreatic masses. J Comput Assist Tomogr 1996; 20(3):363-369.

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J. Anthony Parker, MD PhD, Tony_Parker@bidmc.harvard.edu