Ferdinando Calabria

18F-choline PET/CT pitfalls in image interpretation: An update on 300 examined patients with prostate cancer

Objectives 18F-choline PET/CT is an important diagnostic tool in the management of patients with prostate cancer (PC). The aim of this study was to describe and discuss some abnormal sites of uptake that we observed, not due to PC recurrence. Patients and Methods Three hundred patients were submitted to 18F-choline PET/CT for staging or restaging of PC. Whole-body PET/CT was acquired 40 minutes after the 18F-choline administration. Results We found abnormal uptake of the tracer, not related to PC, in 48/300 patients (16%). Most of these findings were due to inflammatory processes. Furthermore, some malignant conditions, such as a case of colon cancer, a case of bladder carcinoma, and a multiple myeloma, were diagnosed. Mild uptake was also detected in some benign diseases, such as thymoma, adrenal adenoma, and sarcoidosis. Six patients showed focal brain uptake in correspondence to a meningioma. Conclusions It is necessary for nuclear physicians, during clinical practice, to consider the possibility of 18F-choline uptake in some benign or malignant conditions for the intrinsic pharmacologic property of the tracer. An accurate medical investigation, correlative imaging with CT and/or MRI with contrast agents, laboratory data, and above all, histologic examination are often necessary for correct diagnosis.

Role of combined DWIBS/3D-CE-T1w whole-body MRI in tumor staging: Comparison with PET-CT

OBJECTIVES To assess the diagnostic performance of whole-body magnetic resonance imaging (WB-MRI) by diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) in malignant tumor detection and the potential diagnostic advantages in generating fused DWIBS/3D-contrast enhanced T1w (3D-CE-T1w) images. METHODS 45 cancer patients underwent 18F-FDG PET-CT and WB-MRI for staging purpose. Fused DWIBS/3D-CE T1w images were generated off-line. 3D-CE-T1w, DWIBS images alone and fused with 3D-CE T1w were compared by two readers groups for detection of primary diseases and local/distant metastases. Diagnostic performance between the three WB-MRI data sets was assessed using receiver operating characteristic (ROC) curve analysis. Imaging exams and histopathological results were used as standard of references. RESULTS Areas under the ROC curves of DWIBS vs. 3D-CE-T1w vs. both sequences in fused fashion were 0.97, 0.978, and 1.00, respectively. The diagnostic performance in tumor detection of fused DWIBS/3D-CE-T1w images were statistically superior to DWIBS (p<0.001) and 3D-CE-T1w (p≤0.002); while the difference between DWIBS and 3D-CE-T1w did not show statistical significance difference. Detection rates of malignancy did not differ between WB-MRI with DWIBS and 18F-FDG PET-CT. CONCLUSION WB-MRI with DWIBS is to be considered as alternative tool to conventional whole-body methods for tumor staging and during follow-up in cancer patients.

Deeply infiltrating endometriosis: evaluation of retro-cervical space on MRI after vaginal opacification.

OBJECTIVES To prospectively investigate diagnostic value and tolerability of MRI after intra-vaginal gel opacification for diagnosis and preoperative assessment of deeply infiltrating endometriosis. METHODS Sixty-three women with clinical suspicion of deeply infiltrating endometriosis were previously examined with trans-vaginal ultrasonography and then with MRI pre and post administration of vaginal gel. We evaluated the tolerability of this procedure with a scoring scale from 0 to 3. We also assessed with a score from 1 to 4 the visibility of four regions: Douglas-pouch, utero-sacral-ligaments, posterior-vaginal-fornix and recto-vaginal-septum. All patients underwent laparoscopic surgery after MRI. RESULTS Five patients considered procedure intolerable. Visibility of utero-sacral-ligaments and posterior-vaginal-fornix showed to be increased with gel (p<0.001). In 57 out of 80 patients the MRI has allowed us to diagnose deeply infiltrating endometriosis. Overall, the percentages of MRI-sensitivity, specificity, positive predictive value and negative predictive value were respectively 67.8%, 95.3%, 89.4 and 83.5% without gel, and 90.8%, 94.6%, 90.8% and 94.6% with gel; trans-vaginal ultrasonography sensitivity, specificity, positive predictive value and negative predictive value were 57.5%, 96.6%, 90.9% and 79.5%. In evaluation of utero-sacral-ligaments trans-vaginal ultrasonography, MRI without gel and with gel sensitivity was respectively 61.9%, 47.6% and 81%; for recto-vaginal-septum these values were 12.5%, 68.7% and 93.7%; for pouch of Douglas 82%, 87% and 97.4%; finally for posterior-vaginal-fornix 27.3%, 36.4% and 81.8%. CONCLUSIONS MRI with gel opacification of vagina should be recommended for suspicion of deep infiltrating endometriosis, in particular for the added value in evaluation of recto-vaginal septum, utero-sacral ligaments and posterior vaginal fornix.

Molecular imaging of brain tumors with 18F-DOPA PET and PET/CT.

The objective of this study was to give an overview of the potential clinical utility of [18F]-L-dihydroxyphenylalanine (18F-DOPA) PET and PET/CT for imaging of brain tumors. Review articles and reference lists were used to supplement the search findings. 18F-DOPA has been investigated as a PET tracer for primary brain tumors, metastases of somatic cancer, and evaluation of relapse of pathology in patients with brain tumor after surgery and/or radiotherapy on the basis of enhanced cell proliferation. Available studies have provided encouraging preliminary results for diagnosis of brain tumors and relapse after surgery/radiotherapy. In the brain, excellent discrimination between tumor and normal tissue can be achieved because of the low physiological uptake of 18F-DOPA and the high ratio between tumor and normal hemispheric tissue. Information on evaluation of brain metastases is limited but encouraging. PET and PET/CT with 18F-DOPA are useful in diagnosing primary brain tumors and should be recommended in the diagnosis of relapse of disease after surgical treatment and/or radiotherapy. Semiquantitative analysis could improve diagnosis while correlative imaging with MRI is essential. Limits are due to low knowledge of potential pitfalls.

A case of thymoma detected by 18F-choline positron emission tomography/computed tomography

Positron emission tomography/computed tomography (PET/CT) with choline, labelled with nuclides like C or F, is an important diagnostic tool in the management of oncologic diseases with low glucose metabolism and is currently employed in patients with prostate cancer (PC) [1, 2]. A 60-year-old man in restaging of PC underwent Fcholine PET/CT because of increased serum prostatespecific antigen (PSA) levels (2.25 ng/ml) and a bone scan suspicious for metastases 1 year after radical prostatectomy. The patient had not received hormone therapy in the 2 months previous to the exam date. No lymph node or bone metastases were detected on F-choline PET/CT. PET images showed prominent uptake in the mediastinum (a), with a maximum standardized uptake value (SUVmax) of 8. Fused PET/CT and CT views clearly showed that accumulation corresponded to a welldefined, non-homogeneous area of 6 cm with calcifications in the upper mediastinum (b, b’, c, c’). The patient did not suffer any symptoms related to a “mediastinal mass” prior to performance of the exam. Subsequently histopathological analysis, after a CTguided biopsy, diagnosed epithelial thymoma. Is known that proliferation of benign cellular types such as lymphocytes may be responsible for increased choline uptake in benign diseases such as phlogosis [3]. F-FDG PET/CT enables accurate preoperative evaluation of mediastinal masses, especially considering SUVmax as an indicator of malignant behaviour [4], but no data have been reported about choline uptake in thymoma. In clinical practice nuclear physicians cannot exclude the possibility of abnormal uptake of choline, not related to PC, in some oncologic and non-oncologic conditions. Knowledge of CT findings is important; the histological exam still remains the most important step for diagnosis.

The optimal timing to perform 18F/11C-choline PET/CT in patients with suspicion of relapse of prostate cancer: trigger PSA versus PSA velocity and PSA doubling time.

Abstract In the present short communication we considered the main publications focused on trigger prostate-specific antigen (PSA) and PSA kinetics that systematically compared 18F to 11C-choline PET/CT in order to establish the optimal time to perform choline PET/CT in relation to the trigger values and velocity, as well as doubling time of PSA serum levels.

Evaluation of extraprostatic disease in the staging of prostate cancer by F-18 choline PET/CT: can PSA and PSA density help in patient selection?

Objective The aim of our study was to evaluate the accuracy of F-18 choline positron emission tomography/computed tomography (PET/CT) in assessing the presence of extraprostatic disease during staging of prostate cancer, in relation to prostate-specific antigen (PSA) and PSA density, a PSA derivative that is useful for improving risk stratification in prostate cancer patients. Methods F-18 choline PET/CT was performed in 45 patients for early staging of biopsy-proven prostate cancer. None of the examined patients had received therapy before the examination. In all of them a transrectal ultrasonography had been performed earlier to calculate the prostate volume and PSA density. The mean PSA value was 25.5 (±38.1) ng/ml, whereas the mean PSA density was 0.70 (±0.88). Results Results of F-18 choline PET/CT were related to PSA and PSA density. PET/CT was positive for extraprostatic disease in 18/45 patients (40%) (mean PSA and PSA density were, respectively, 44.08 ng/ml and 1.08); PET/CT was negative for extraprostatic disease in 27/45 patients (60%) (mean PSA and PSA density were, respectively, 13.12 ng/ml and 0.4). PET/CT was positive in 13/18 patients (72%) with a PSA cutoff value greater than or equal to 18 ng/ml and in 5/21 (24%) with a PSA value less than 18 ng/ml (P=0.0017). PET/CT was positive in 16/18 patients (89%) with PSA density greater than or equal to 0.31 and in 2/18 (11%) with PSA density lower than 0.31 (P=0.0234). Conclusion The possibility of detecting extraprostatic disease of prostate cancer with F-18 choline PET/CT is related to PSA and PSA density. In particular, F-18 choline PET/CT should be recommended only in patients with a PSA value of at least 18 ng/ml, whereas a PSA density of at least 0.31 ng/ml is more probably associated with distant metastases.

Recurrent glioma and crossed cerebellar diaschisis in a patient examined with 18F-DOPA and 18F-FDG PET/CT.

Two years after resection of a left parietal glioma, a 46-year-old woman underwent F-FDG and F-DOPA brain PET/CT. FDG showed left parietal hypometabolism with crossed cerebellar diaschisis. No abnormally increased FDG activity was seen. F-DOPA PET/CT scan demonstrated focal left parietal uptake. Recurrent glioma was confirmed by surgical biopsy. F-DOPA may demonstrate abnormal amino acid metabolism in evaluation of recurrence of glioma.

Lhermitte-Duclos disease presenting with positron emission tomography-magnetic resonance fusion imaging: a case report

IntroductionLhermitte-Duclos disease or dysplastic gangliocytoma of the cerebellum is an extremely rare tumor. It is a slowly enlarging mass within the cerebellar cortex. The majority of cases are diagnosed in the third or fourth decade of life.Case presentationWe report the case of a 37-year-old Caucasian woman who underwent positron emission tomography-computed tomography with fluorine-18-fluorodeoxyglucose for evaluation of a solitary lung node. No pathological uptake was detected in the solitary lung node but the positron emission tomography-computed tomography of her brain showed intense tracer uptake, suggestive of a malignant neoplasm, in a mass in her left cerebellar lobe. Our patient had experienced two years of occipital headache and movement disorder. Subsequently, magnetic resonance imaging was performed with contrast agent administration, showing a large subtentorial mass in her left cerebellar hemisphere, with compression and dislocation of the fourth ventricle. Metabolic data provided by positron emission tomography and morphological magnetic resonance imaging views were fused in post-processing, allowing a diagnosis of dysplastic gangliocytoma with increased glucose metabolism. Total resection of the tumor was performed and histological examination confirmed the diagnosis of Lhermitte-Duclos disease.ConclusionsOur case indicates that increased uptake of fluorine-18-fluorodeoxyglucose may be misinterpreted as a neoplastic process in the evaluation of patients with Lhermitte-Duclos disease, but supports the usefulness of integrated positron emission tomography-magnetic resonance imaging in the exact pathophysiologic explanation of this disease and in making the correct diagnosis. However, an accurate physical examination and exact knowledge of clinical data is of the utmost importance.

A case of intracranial meningioma detected by 18F-choline PET/CT and examined by PET/MRI fusion imaging

A 73-year-old man was submitted to 18F-choline PET/CT for restaging prostate cancer (PSA = 1.3 ng/ml). A whole body PET/CT scan was acquired, from the vertex of the skull to proximal thigh. At brain level, a single area of focal 18Fcholine uptake, with SUVmax = 3, was detected in left frontal region (a, axial PET view). No morphological abnormalities were detected in the co-registered CT scan at this level. Furthermore, the patient did not reported neurologic symptoms. Subsequently, an MR was performed and diagnosed an intracranial meningioma in the same brain region, with hyperintensity on T2-FLAIR axial images (b) and mild enhancement on the post-contrast T1-weighted images (c). A fused PET/MR view obtained during the post-processing confirmed the correct identification of the lesion (d) (Fig. 1). Any area of pathologic tracer uptake due to relapse of prostate cancer was detected in the whole body PET/CT. It is known that the meningiomas show high uptake of choline due to the overall increased metabolism of cell membrane.1 Similarly to 18F-DOPA,2 the 18F-choline shows a low physiological uptake in the brain and it presents a tumor-to-background ratio much higher than 18F-FDG: this feature can help in detecting meningiomas in patients examined for prostate cancer. On the other hand, MR still remains the best reference imagical modality in this field, because of its high spatial resolution. Furthermore, the added value of MR is due to the possibility of multiplanar evaluation, which allow for a better depiction of the brain structures. This report describes the potential usefulness of PET/MR fusion software in morphological and functional characterization of a brain lesion. The combined evaluation of metabolic imaging of PET and morphological features provided by MR could play a role in better depicting the findings of focal uptake of 18F-choline in the