Clinical application of [18F]FDG PET/CT in follicular lymphoma

The objective of the present paper was to review the clinical application of [¹⁸F]FDG PET/CT in follicular lymphoma (FL). Once it was clear that, despite it is characterized as indolent, this type of lymphoma usually shows a high [¹⁸F]FDG avidity, PET/CT became more important and it's now considered the standard technique in staging, re-staging and response evaluation. Many studies have shown its impact on the management of patients (as it can change the stage in a significant proportion of cases and lead to treatment modifications), its superiority over CT (mainly because it's able to distinguish fibrosis in residual masses from viable tumor) and its prognostic value. The latter was initially associated only to the degree of metabolic response, which has proved to be a strong and independent predictive factor in terms of disease-free survival (DFS) and overall survival (OS). Thus, a negative PET/CT scan could be considered a guarantee in high-tumor-burden follicular lymphoma patients. However, semiquantitative parameters such as metabolic tumor volume or total lesion glycolysis, may also provide useful information and help us to identify patients with poor prognosis, guiding a risk-adjusted management and follow-up.

Preparation, radiolabeling with 99mTc and 67Ga and biodistribution studies of albumin nanoparticles covered with polymers

OBJECTIVE

To optimize radiolabeling with ^99mTc and ⁶⁷Ga of albumin nanoparticles coated with 4 differents synthetic polymers and to evaluate their stability in vivo and in vitro, as well as their biodistribution in vivo after intravenous administration.

MATERIAL AND METHODS

The nanoparticles were prepared using albumin and NOTA-modified albumin by the desolvation method and coated with 4 different polymers; HPMC, GMN2, GPM2 and GTM2. They were purified, lyophilized and characterized. Radiolabelling with ^99mTc was perfomed with 74 MBq of ^99mTc sodium pertechnetate, previously reduced with and acid solution of tin chloride at different concentrations (0.003, 0.005, 0.007, 0.01, 0.05 and 0.1mg/ml) and at different times (5, 10, 15, 30 and 60minutes) and temperatures (room temperature, 40°C and 60°C). Radiolabelling with ⁶⁷Ga was perfomed by incubation of the nanoparticles with 37 MBq of ⁶⁷Gallium chloride (obtained from commercial gallium-⁶⁷ citrate) at different times (10 and 30minutes) and temperatures (room temperature, 30°C and 60°C), and posterior purification with microconcentrators. The radiochemical purity was evaluated by TLC. Stability studies of radiolabeled nanoparticles in physiological serum and blood plasma were perfomed. Biodistribution studies of nanoparticles coated with GPM2 polymer were carried out in Wistar rats after intravenous administration of the nanoparticles. Control animals were carried out with ^99mTc sodium pertechnetate and ⁶⁷Ga chloride. To do so, the animals were killed and activity in organs was measured in a gamma counter.

RESULTS

^99mTc labeling was carried out optimally with a tin concentration of 0.007mg/ ml for the GPM2 nanoparticles and 0.005mg / ml for the rest of the formulations, with a radiolabelling time of 10minutes at room temperature. In the case of ⁶⁷Ga the label was optimized at 30° C temperature and 30minutes of incubation. In both cases the radiochemical purity obtained was greater than 97%. The nanoparticles showed high stability in vitro after 48hours of labeling (70% nanoparticles labeled with ^99mTc and 90% those labeled with ⁶⁷Ga). Biodistribution studies of nanoparticles ^99mTc -GPM2 and ⁶⁷Ga -NOTA-GPM2 showed a high accumulation of activity in the liver at 2 and 24hours after intravenous administration.

CONCLUSION

The labeling procedure with ^99mTc and ⁶⁷Ga of albumin and albumin modified with NOTA nanoparticles allows obtaining nanoparticles with high labeling yields and adequate in vitro stability, allowing their use for in vivo studies.

FDG PET/CT in colorectal cancer

Colorectal cancer is the third most frequent cancer worldwide. Although its incidence is increasing, mainly in those aged under50, mortality has decreased by 50% in the more developed countries, principally due to the adoption of new practices in prevention, diagnosis and treatment. In particular, the various diagnostic imaging modalities allow improved therapeutic decision-making, evaluation of the response and early detection of recurrence. The aim of this paper is to review the available scientific evidence on the value of positron emission tomography with ¹⁸F-FDG (¹⁸F-FDG PET/CT) in the colorectal cancer, with special emphasis on the indications of the guidelines and recommendations of the main international scientific associations regarding this imaging technique.

18F-FDG PET/CT in locally advanced cervical cancer: A review

Cervical cancer is the second most common gynecological cancer worldwide. In locally advanced cervical cancer, ¹⁸F-FDG PET/CT has become important in the initial staging, particularly in the detection of nodal and distant metastasis, aspects with treatment implications and prognostic value. The aims of this study were to review the role of ¹⁸F-FDG PET/CT in uterine cervical cancer, according to the guidelines of the main scientific institutions (FIGO, NCCN, SEGO, SEOM, ESGO, and ESMO) and its diagnostic accuracy compared to conventional radiological techniques, as well as to review the acquisition protocol and its utility in radiotherapy planning, response assessment and detection of recurrence.

Radium-223 in the treatment of bone metastasis in patients with castration-resistant prostate cancer. Review and procedure

Bone metastatic disease is the main cause of morbidity / mortality in patients with prostate cancer, presenting frequently as bone pain, pathological fractures or spinal cord compression, which requires early and timely therapy. Although, for the moment, the therapeutic window for its use has not been definitively established, radium-223 (²²³Ra), an alpha particle emitter, has proved to be an effective therapeutic tool, pre or post-chemotherapy, in patients with castration-resistant prostate cancer with symptomatic bone metastases and absence of visceral metastases, significantly modifying the prognosis of the disease. It is therefore imperative to define the ideal scenarios and the correct protocol for the use of this therapy and thus offer the greatest possible clinical benefit to the patient.

Contribution of 11C-Choline PET/CT in prostate carcinoma biochemical relapse with serum PSA level below 1 ng/ml

OBJECTIVE

¹¹C-choline PET/CT has demonstrated good results in the restaging of prostate cancer (PCa) with high serum prostate specific antigen (PSA), but its use in patients with low serum PSA is controversial. Our aim was to evaluate the contribution of ¹¹C-choline PET/CT in patients with PCa, biochemical relapse and PSA <1 ng/ml.

MATERIAL AND METHOD

Fifty consecutive patients (mean age: 65.9±5.6 years) with biochemical relapse of PCa and serum PSA <1ng/ml were evaluated retrospectively. PET/CT was performed 20min after intravenous administration of 555-740 MBq of ¹¹C-choline. Minimum follow up time was 30 months.

RESULTS

Twenty-one out of 50 patients (42%) had an abnormal ¹¹C-choline PET/CT. In 7 out of 21 patients (14%) tumor was confirmed (4 in prostatic bed, 4 in pelvic lymph nodes, 2 in mediastinal lymph nodes and one synchronous sigmoid carcinoma), and in all cases the initial therapeutic planning was modified. In 2 patients (4%) subsequent tests diagnosed a benign disease (one sarcoidosis, one tuberculosis sequelae) and in 3 patients (6%) they ruled out pathology. The other 9 patients (18%) had no further assessment (7 mediastinal and 4 pelvic lymph nodes). Twenty-nine out of 50 patients (58%) had a normal PET/CT. At 30 months, follow up recurrence was confirmed only in 2 of these patients.

CONCLUSIONS

¹¹C-choline PET/CT proved its usefulness in demonstrating tumor in 14% of patients with BR of PCa and serum PSA <1ng/ml, with therapeutic implications. In 4% of patients a benign condition was detected. A normal ¹¹C-choline PET/CT was associated with a very low rate of recurrence at 30 months.

Patterns of 11C-PIB cerebral retention in mild cognitive impairment patients

OBJECTIVE

To evaluate the patterns of cerebral cortical distribution of (11)C-PIB in patients with mild cognitive impairment (MCI).

MATERIAL AND METHODS

The study included 69 patients (37 male, age range 42-79 years) with MCI, sub-classified as 53 with amnestic-MCI (A-MCI), and 16 with non-amnestic-MCI (NA-MCI). Patients underwent (11)C-PIB PET/CT scan 60min after intravenous injection of the radiotracer. A visual analysis of the images was performed by 2 experienced physicians. (11)C-PIB-positive studies were considered when gray matter uptake was equal to or greater than white matter. According to the regions involved, (11)C-PIB-positive studies were classified into A-pattern (predominant retention in frontal, anterior cingulate, lateral temporal, and basal ganglia) and B-pattern (generalized retention).

RESULTS

Thirty-nine of the 69 (56%) patients with MCI showed (11)C-PIB retention. Of the 53 A-MCI patients, 36 (68%) showed (11)C-PIB retention. Eleven out of 36 (30%) positive scans in A-MCI patients showed A-pattern, and 25 out of 36 (70%) patients had a B-pattern. Positive (11)C-PIB was observed in 3 out of 16 (19%) patients with NA-MCI. Regional distribution in these 3 patients showed A-pattern in 1, and B-pattern in 2 patients.

CONCLUSION

Cortical retention of (11)C-PIB was more frequent in A-MCI than in NA-MCI patients, and also B-pattern than A-pattern in the (11)C-PIB positive group. The recognition of (11)C-PIB distribution patterns allows MCI patients to be classified, and the A-pattern may offer a therapeutic window for potential future treatments.

Comparison of 99mTc-sestamibi and 11C-methionine PET/CT in the localization of parathyroid adenomas in primary hyperparathyroidism

AIM

To evaluate the usefulness of (11)C-methionine PET/CT (MET) in the localization of the parathyroid adenomas and to compare the results with those obtained with the conventional technique in double-phase (99m)Tc-sestamibi scintigraphy (MIBI). We evaluated the optimal timing to acquire MET images.

MATERIAL AND METHODS

A prospective study that included 14 patients (mean age: 65.5 ± 9.7 years) with primary hyperparathyroidism (PH) who underwent surgery was performed. Mean serum iPTH was 215.8 ± 108 pg/mL and serum calcium 10.8 ± 0.9 mg/dL. MIBI (planar and SPECT) was obtained 10 min and 2-3h after injection of 740 MBq (20 mCi) of (99m)Tc-sestamibi. MET was obtained 10 min and 40 min after injection of 740 MBq (20 mCi) of (11)C-methionine. MIBI and MET images were visually evaluated and compared. A score for 10 min and 40 min MET images from 0 (no abnormal uptake) to 3 (intense uptake) was assigned.

RESULTS

MIBI and MET were positive and concordant in 11/14 patients and in 10 of them the parathyroid adenoma was correctly localized. In 3/14 MIBI was positive and MET negative (MIBI correctly localized the parathyroid adenoma in 2 of them). According to the timing of MET imaging acquisition, the 10 min and 40 min acquisition showed the same score in 10 patients, it was higher at 10 min acquisition in 3 and in 1 the parathyroid adenoma was only detected at 40 min acquisition.

CONCLUSION

MIBI remains the technique of choice for the localization of parathyroid adenomas in patients with PH. MET may play a complementary role in selected patients. Delayed acquisition should be included in the MET protocol when the early acquisition is negative.