[18F]‐fluorocholine positron‐emission/computed tomography for lymph node staging of patients with prostate cancer: preliminary results of a prospective study

Study Type – Diagnostic (case series)
Level of Evidence 4

OBJECTIVES

To evaluate prospectively [¹⁸F]‐fluorocholine positron‐emission/computed tomography (FCH PET/CT) for lymph node staging of prostate cancer before intended curative therapy, and to determine whether imaging 15 or 60 min after radiotracer injection is preferable.

PATIENTS AND METHODS

In all, 25 consecutive patients with newly diagnosed prostate cancer (Gleason score >6, and/or a prostate‐specific antigen level of >10 ng/mL, and/or T3 cancer) were scanned before lymphadenectomy. Each patient was assessed twice with imaging, at 15 and 60 min after the injection with FCH. Images were compared with the results of histopathological examination of the surgically removed lymph nodes. Maximum standardized uptake values (SUV_max) at 15 and 60 min were also compared.

RESULTS

Histopathologically, metastases were present in removed lymph nodes from three patients. FCH PET/CT showed a high radiotracer uptake in four patients, the former three and a fourth. The sensitivity, specificity, positive and negative predictive value of FCH PET/CT for patient based lymph node staging of prostate cancer were 100%, 95%, 75% and 100%, respectively; the corresponding 95% confidence intervals were 29.2–100%, 77.2–99.9%, 19.4–99.4% and 83.9–100%, respectively. Values of SUV_max at early and late imaging were not significantly different.

CONCLUSIONS

This small series supports the use of FCH PET/CT as a tool for lymph node staging of patients with prostate cancer. Values of SUV_max at early and late imaging did not differ. However, larger prospective studies are needed to validate these findings.     

Clinical significance of incidental focal colorectal 18F‐fluorodeoxyglucose uptake: our experience and a review of the literature

Aim The aims of the present study were: (i) to evaluate the focal incidental colorectal uptake of ¹⁸F‐fluorodeoxyglucose ([¹⁸F]FDG) and to correlate it with colonoscopy and histological findings; (ii) to evaluate the relationship between the presence/absence of neoplastic disease and clinical data and the anatomical site of [¹⁸F]FDG uptake; and (iii) to compare our results with those reported for incidental colorectal uptake of [¹⁸F]FDG in the literature and those obtained from various screening programmes for colorectal cancer. Method The database of 6000 patients referred for [¹⁸F]FDG positron emission tomography/computed tomography (PET‐CT) to our centre was retrospectively reviewed for incidental colorectal uptake of [¹⁸F]FDG. Patients with focal uptake were selected and the aetiology of PET findings was verified with a subsequent colonoscopy and histopathological analysis when available. Results Incidental colorectal uptake of [¹⁸F]FDG was seen in 144 (2.4%) patients, of whom 64 (1.1%) had focal uptake; 48 out of these 64 patients underwent colonoscopy, which showed malignant tumours in 12 (25%), premalignant lesions in 19 (40%), non‐neoplastic lesions in six (12%) and lesions not confirmed by colonoscopy in 11 (23%). Our data agreed with previously published data. Statistical analysis did not show any significant relationship between the presence/absence of neoplastic disease and patient sex or age, type of primary disease and anatomical site of [¹⁸F]FDG uptake. Comparing our data with various screening programmes, a significant difference was found only with series in which colonoscopy was performed in patients at high risk for colorectal cancer. Conclusion Focal incidental colorectal uptake of [¹⁸F]FDG is observed in about 1% of PET/CT studies and carries a high risk of neoplastic disease. A PET‐CT report should suggest colonoscopy when abnormal findings are reported.     

Combined 18F‐fluorocholine and 18F‐fluoride positron emission tomography/computed tomography imaging for staging of high‐risk prostate cancer

Study Type – Diagnosis (cohort) Level of Evidence 2a What's known on the subject? and What does the study add? Positron emission tomography/computed tomography (PET/CT) with choline and fluoride for the detection of metastases in patients with prostate cancer have each been evaluated, with mixed results. Choline PET/CT has been evaluated against pelvic lymphadenectomy, generally with a low sensitivity but a high specificity; however, the study populations have been heterogenous. Fluoride PET/CT has been evaluated against other imaging methods, such as bone scan, single photon emission CT and MRI, and has been shown to have high specificity as well as sensitivity for bone metastases, but there are no studies with biopsy verification. This is the first study that evaluates the clinical use of both choline and fluoride PET/CT on the same patients in a well‐defined population of patients with high‐risk prostate cancer.

OBJECTIVE

• ? To investigate how often positron emission tomography/computed tomography (PET/CT) scans, with both ¹⁸F‐fluorocholine and ¹⁸F‐fluoride as markers, add clinically relevant information for patients with prostate cancer who have high‐risk tumours and a normal or inconclusive planar bone scan.

PATIENTS AND METHODS

• ? Patients with prostate cancer with prostate specific antigen (PSA) levels between 20 and 99 ng/mL and/or Gleason score 8–10 tumours, planned for treatment with curative intent based on routine staging with a negative or inconclusive bone scan, were further investigated with a ¹⁸F‐fluorocholine and a ¹⁸F‐fluoride PET/CT.
• ? None of the patients received hormonal therapy before the staging procedures were completed.

RESULTS

• ? For 50 of the 90 included patients (56%) one or both PET/CT scans indicated metastases.
• ? ¹⁸F‐fluorocholine PET/CT indicated lymph node metastases and/or bone metastases in 35 patients (39%).
• ? ¹⁸F‐fluoride PET/CT was suggestive for bone metastases in 37 patients (41%).
• ? In 18 patients (20%) the PET/CT scans indicated widespread metastases, leading to a change in therapy intent from curative to non‐curative.
• ? Of the patients with positive scans, 74% had Gleason score 8–10 tumours. Of the patients with Gleason score 8–10 tumours, 64% had positive scans.

CONCLUSIONS

• ? PET/CT scans with ¹⁸F‐fluorocholine and ¹⁸F‐fluoride commonly detect metastases in patients with high‐risk prostate cancer and a negative or inconclusive bone scan.
• ? For 20% of the patients the results of the PET/CT scans changed the treatment plan.

     

Colorectal tubulovillous adenomas identified on fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography scans

Objective The aim of this retrospective study was to assess the significance of incidental focal colonic lesions on fluoro‐2‐deoxy‐d ‐glucose positron emission tomography/computed tomography (FDG PET/CT) scans in patients undergoing staging for noncolorectal cancer. Method Of the 110 patients in our PET/CT database, 10 were found to have abnormally high uptake of tracer in their large bowel. Results Seven patients who underwent further endoscopic evaluation of these abnormalities had intermediate to high‐risk adenomatous polyps. Conclusion Benign colonic polyps produce high‐intensity focal FDG uptake in large bowel. Endoscopic evaluation is recommended before curative resectional surgery of the presenting cancer where appropriate.     

The distinctive role of positron emission tomography/computed tomography in breast carcinoma with brown adipose tissue 2-fluoro-2-deoxy-d-glucose uptake

The diagnostic power of an integrated positron emission tomography/computed tomography (PET/CT) system for whole-body 2-fluoro-2-deoxy-d-glucose (FDG) imaging is clearly demonstrated in this case report. The precise anatomic localization of FDG uptake with CT in a PET/CT scan of a patient with known breast carcinoma helped identify a contralateral breast tumor with axillary lymph node metastasis despite the presence of extensive physiologic brown fat FDG uptake. Accordingly, the patient received appropriate surgical management and pathologic confirmation of the disease.     

The clinical advances of fluorine‐2‐D‐deoxyglucose – positron emission tomography/computed tomography in urological cancers

Fluorine‐18 labeled fluorine‐2‐D‐deoxyglucose (FDG) is the most frequently used positron emission tomography (PET) probe but it has certain limitations when used in urological cancers. The introduction of co‐registered PET and computed tomography (PET/CT) represents a major advance in technology and FDG‐PET/CT has now become the new standard. The diagnostic performance of FDG‐PET and PET/CT depends on the metabolic activity of tumor tissue, which is generally low in primary renal cell and prostate cancers and often in their metastatic deposits. In contrast, both seminomatous and nonseminomatous germ cell tumors are characterized by upregulated glucose metabolism with subsequently increased FDG uptake in tumor sites. Generally, the metabolic activity provides accurate information regarding the presence of a viable tumor, except in patients with residual mature teratoma. Although bladder cancer demonstrates sufficiently increased FDG uptake, primary tumors are difficult to identify due to the renal excretion of FDG. The accuracy of FDG‐PET/CT in metabolically active metastases is generally higher compared to conventional CT except for identifying small lung deposits. With disease progression and subsequent de‐differentiation of prostate cancer, castrate resistant disease is more likely to present with lesions that have increased glucose metabolism.