Usefulness of 124I PET/CT imaging to predict absorbed doses in patients affected by metastatic thyroid cancer and treated with 131I.

AIM: The aim of this work was the evaluation of the usefulness of 124I PET/CT sequential scans to predict absorbed doses to metastatic thyroid cancer in patients undergoing 131I therapy. METHODS: From July 2011 until April 2012 8 patients affected by metastatic thyroid cancer were enrolled. Each patient underwent 4 PET/CT scans at 4, 24, 48, 72 h after the administration of about 74 MBq of 124I. Blood samples and whole body exposure measurements were obtained to calculate blood and red marrow doses. Activity concentrations and lesion volumes obtained from PET/CT images were used to evaluate tumour doses with MIRD formalism and spheres model. The average administered 131I therapeutic activity was 6475 MBq (range: 3700-9250 MBq). RESULTS: 124I PET/CT images showed, with a very good resolution, all 131I avid lesions detected by post therapy whole body scans. The average dose rates for blood, red marrow and lesions were respectively: 6.58E-02 ± 1.64E-02 mGy/MBq, 5.73E-02 ± 1.57E-02 mGy/MBq, 2.22E+01 ± 1.62E+01 mGy/MBq. Three out of eight patients did not show any uptake of 124I in all PET/CT scans, despite high level of TSH and CT detectable lesions. Post-therapy 131I whole body scan confirmed the absence of focal iodine uptake. CONCLUSION: Negative 124I PET/CT images probably could be used as predictive of real absence of iodine avidity, avoiding all toxicity from useless 131I therapy. A higher number of patients is necessary to validate these preliminary results and a project is ongoing to compare MIRD results to voxel dosimetry based on Monte Carlo simulation.

Spinal infection multidisciplinary management project (SIMP): from diagnosis to treatment guideline.

Spine infections require a multidisciplinary approach to be treated and solved. A guide line to drive physicians in the deep complexity of such a disease is extremely helpful. SIMP suggests a flow-chart built up on clear concepts such as right and well managed antibiotic therapy, sound stability of the spine, correct and smart use of the standard and functional imaging techniques, such as f18 FDG PET/CT. In 16 months a total of 41 patients have been treated for spondylodiscitis, discitis and vertebral osteomyelitis by our team of physicians and 25 patients have been enrolled in a prospective study whose target is the assessment of the SIMP flow-chart and of every single aspect that characterize it.

Molecular imaging and targeted therapies in oncology: new concepts in treatment response assessment. a collection of cases.

The widespread use of several new non-cytotoxic drugs and the significant improvements in functional imaging highlights a number of difficulties in monitoring, interpreting and predicting treatment response in clinical practice. Certain guidelines for disease assessment after therapy are already available: the traditional Response Evaluation Criteria in Solid Tumours guidelines based on tumour size variations using conventional imaging technologies, the recent combined method developed by Choi and colleagues in gastrointestinal stromal tumour treated with tyrosine kinase inhibitors based on tumour density variations using computed tomography (CT), and the European Organization for Research and Treatment of Cancer criteria based on tumour glucose metabolism variations using fluorodeoxyglucose (FDG) positron emission tomography (PET). At the moment combined PET/CT response criteria are still not available. A number of new PET compounds other than FDG are also currently being developed to visualize specific cellular and molecular tumour pathways but their role in assessment and prediction of cancer treatment response has not yet been thoroughly investigated in a large series. However, in clinical practice many oncologists treat cancer patients with targeted therapies or chemotherapy and evaluate the response using conventional or functional imaging without appropriate and standardized guidelines. The aim of this study was to present a selection of clinical cases that illustrate the usefulness of new PET tracers and efficacy evaluation of new drugs. In the era of molecular imaging and molecular therapies, these cases highlight the urgency to develop new criteria for treatment assessment and the exigency of correctly interpreting the biological information obtained from new technologies, and introduce new concepts that require further investigation in clinical trials.

Cryptogenic stroke in children: possible role of patent foramen ovale.

Stroke is a rare disorder in childhood. The majority of these cases is of an ischemic nature. In spite of the long list of known causes, many strokes remain undetermined, so-called cryptogenic strokes. Increasing evidence indicates that, in the young adults, many cases of cryptogenic stroke are presumably due to paradoxical embolism. In childhood, this is usually not considered, unless in the context of a complex cyanotic heart disease. We present two cases, a 6-year-old boy and an 11-year-old girl who had an episode of cerebral ischemia documented by MRI, and in whom the only anomaly found was a patent foramen ovale (PFO) with intermittent left to right shunt at rest, but with a large right to left shunt during the Valsalva maneuvre. We assumed that, in our cases, in the absence of identifiable causes, the cerebral ischemia was most likely due to paradoxical embolism through the PFO. Of course, as in the adult, the paradoxical embolism could not be proved, but in our opinion it remains the most concrete possibility. Therefore, in presence of a cryptogenic stroke, a PFO should be investigated also in children.