Role of 18F-FDG PET/CT in primary brain lymphoma. / Utilidad de la 18F-FDG PET/TC en el linfoma cerebral primario.

OBJECTIVE: To study the usefulness of 18F-FDG PET/CT in the initial evaluation and in the response assessment in primary brain lymphoma. MATERIAL AND METHODS: A retrospective analysis was carried out on 18 patients diagnosed with primary brain lymphoma, a histological subtype of diffuse large B-cell lymphoma, on whom an initial 18F-FDG PET/CT and MRI was performed, with 7 of the cases being analysed after the completion of treatment in order to assess response and clinical follow up. RESULTS: Initial 18F-FDG PET/CT showed 26 hypermetabolic foci, whereas 46 lesions were detected by MRI. The average SUV maximum of the lesions was 17.56 with T/N 3.55. The concordance of both tests for identifying the same number of lesions was moderate, obtaining a kappa index of 0.395 (P<.001). In the evaluation of treatment, MRI identified 16 lesions compared to 7 pathological accumulations observed by 18F-FDG PET/CT. The concordance of both tests to assess type of response to treatment was moderate (kappa index 0.41) (P=.04). In both the initial evaluation and the assessment of the response to treatment, PET/CT led to a change strategy in 22% of patients who had lesions outside the cerebral parenchyma. CONCLUSIONS: MRI appears to be the method of choice for detecting brain disease in patients with primary brain lymphoma, whereas 18F-FDG PET/CT seems to play a relevant role in the assessment of extra-cerebral disease.

Primary squamous cell carcinoma of the thyroid. Initial assessment and follow-up using 18F-FDG PET/CT. / Carcinoma epidermoide primario de tiroides. Valoración inicial y control evolutivo mediante 18F-FDG PET/TC.

Squamous cell carcinoma of thyroid is an uncommon, very aggressive neoplasm, having a poor prognosis and poor response to chemotherapy and radiotherapy. Surgery is the initial treatment of choice, although it often presents as a widespread disease at the time of diagnosis, usually with cervical swelling that causes most of the symptoms due to local infiltration or metastasis. Local infiltration from adjacent tumour and metastatic disease needs to be excluded from other primary epidermoid carcinomas, in order to make a correct diagnosis. This also requires the typical cytokeratin pattern seen in histological studies. The case is presented of a 53 year-old man with a medical history of hepatocarcinoma, with a cervical hypermetabolic lesion detected in an 18F-FDG PET/CT performed to exclude widespread disease. The follow-up of this lesion with this technique and its usefulness is also described.

Usefulness of 18F-FDG PET/CT in a case of suspected vascular graft infection. / Utilidad de la 18F-FDG PET/TC en un caso de sospecha de infección de injerto vascular.

Vascular prosthetic graft infection (VPGI) is associated with high mortality and morbidity. An early and accurate diagnosis is essential in order to give the most appropriate treatment. The case is presented of a 74 year old male subjected to an aortobifemoral bypass graft, with clinical suspicion of VPGI with inconclusive tests. Later on an 18F-FDG PET/CT study showed a pathological uptake, suggestive of periprosthetic infection, as well as an incidental pulmonary lesion, suggestive of a primary neoplasm. A new 18F-FDG PET/CT showed a significant improvement in the uptake by the vascular graft after prolonged antibiotic treatment. 18F-FDG is a promising tracer for detecting VPGI as the accumulated activated white cells at the infection site have a high demand for 18F-FDG, and could help define the response to antibiotic treatment.

Role of SPECT-CT in sentinel lymph node biopsy in patients diagnosed with head and neck melanoma.

OBJECTIVE: Assess the role of SPECT-CT in sentinel lymph node (SLN) biopsy in the accurate anatomical location of the SNL in patients with cutaneous head and neck melanoma. MATERIAL AND METHODS: A retrospective study was conducted from February 2010 to June 2013 on 22 consecutive patients with a diagnosis of cutaneous head and neck melanoma (9 female, 13 male), with a mean age of 55 years old and who met the inclusion criteria for SLN biopsy. Patients underwent preoperative scanning after peri-scar injection of (99m)Tc-labeled-nanocolloid. Planar images of the injection-site, whole-body, and SPECT-CT scanning were acquired. RESULTS: Detection rate of SLN reached up to 91% (20/22 patients) by planar lymphoscintigraphy and 95.4% (21/22 patients) by SPECT-CT. SPECT-CT provided an accurate location of SLN in 14/22 patients, enabling to improve the surgical approach (clinical impact: 63.6%). SLN was positive for metastatic cells in 9.1% patients. CONCLUSION: SPECT-CT provides detailed anatomical SLN location and allows detecting a higher number of SLN than planar lymphoscintigraphy. Routine use of SPECT-CT is recommended in order to optimise the SLN detection and location in patients with head and neck melanoma.

Radioisotope synoviorthesis in paediatric and adolescent patients with haemophilia.

OBJECTIVE: To assess the outcome and adverse-effects of the radioisotope synoviorthesis in paediatric and adolescent patients with haemophilia. MATERIAL AND METHODS: Prospective study of historical cohort was conducted. A total of 20 consecutive haemophiliacs with a mean age of 13.1 years (range 4-17) were included with a mean follow-up of 64.9 months (range 18-109). The diagnosis of synovitis was established on the basis of clinical follow-up including radiological images (radiography and/or MRI). For evaluation, the classification proposed by Fernandez-Palazzi was used. INCLUSION CRITERIA: Patients aged less than 18 years old with haemophilia and more than one haemarthrosis in less than 3 months remaining a chronic synovitis despite prophylactic therapy intensification. EXCLUSION CRITERIA: Any contraindication for radionuclide synoviorthesis. Twenty-seven radioisotope synoviorthesis with (90)Y-citrate-colloid and/or (186)Re-sulphide-colloid were done. The effectiveness of the procedure was assessed through pre and posttreatment clinical comparison at 6 months after radioisotope synoviorthesis. RESULTS: Nineteen of the 27 synoviorthesis (70.3%) had a good or excellent response and 8 joints (29.7%) had partial response. It was necessary to repeat the procedure in 3 joints in 3 different patients, obtaining in all cases a good or excellent response. We appreciated inflammatory reaction after procedure in 4 cases (14.8%), which improved with analgesics and nonsteroidal anti-inflamatory drugs. None of the patients presented malignant or premalignant lesions during the follow-up. CONCLUSION: The radionuclide synoviorthesis is a very effective procedure in paediatric and adolescent patients with hemophilia, being a minimally invasive procedure, easy to perform, safe and with minimal side effects.

The role of 18FDG, 18FDOPA PET/CT and 99mTc bone scintigraphy imaging in Erdheim-Chester disease.

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocitosis, characterized by multisystemic xanthogranulomatous infiltration by foamy histiocytes that stain positively for CD68 marker but not express CD1a and S100 proteins. Etiology and pathogenesis are still unknown and only about 500 cases are related in the literature. Multisystemic involvement leads to a wide variety of clinical manifestations that results in a poor prognosis although recent advances in treatment. We present the clinical, nuclear medicine findings and therapeutic aspects of a serie of 6 patients with histopathological diagnosis of ECD, who have undergone both bone scintigraphy (BS) and 18F-fluorodeoxyglucose (18FDG)-PET/CT scans in our institution. A complementary 18F-fluorodopa (18FDOPA)-PET/CT was performed in one case. Three different presentations of the disease were observed in our casuistic: most indolent form was a cutaneous confined disease, presented in only one patient. Multifocal involvement with central nervous system (CNS) preservation was observed in two patients. Most aggressive form consisted in a systemic involvement with CNS infiltration, presented in three patients. In our experience neurological involvement, among one case with isolate pituitary infiltration, was associated with mortality in all cases. 18FDG-PET/CT and BS were particularly useful in despite systemic involvement; locate the site for biopsy and the treatment response evaluation. By our knowledge, 18FDOPA-PET/CT not seems useful in the initial staging of ECD. A baseline 18FDG-PET/CT and BS may help in monitoring the disease and could be considered when patients were incidentally diagnosed and periodically 18FDG-PET/CT must be performed in the follow up to evaluate treatment response.

Sentinel lymph node biopsy in paediatric melanoma. A case series.

The incidence of melanoma in children is uncommon, being particularly rare in children under 10 years-old. However, this disease is increasing by a mean of 2% per year. As in adults, the lymph node status is the most important prognostic factor, crucial to performing the selective sentinel lymph node biopsy (SLNB). We report 3 cases of paediatric patients of 3, 4 and 8 years-old, in which SLNB was performed for malignant melanoma. Paediatric age implies greater technical difficulty to the scintigraphy scan due to poor patient cooperation, with mild sedation required in some cases, and only being able to acquire planar images in other cases. SPECT/CT was only performed in the oldest patient. In our cases, SLNB was useful for selecting the least invasive surgery in order to reduce morbidity.

123I-MIBG, 18F-DOPA and 18F-FDG in a patient with MEN2 syndrome and recurrent pheochromocytoma.

Pheochromocytoma is a rare tumor located in the medulla of the adrenal gland that is characterized by high catecholamine synthesis. Surgery is the treatment of choice and is usually curative if appropriately diagnosed and excised. Imaging methods, both morphological and functional, are of great importance in presurgical evaluation. We report the case of a female patient with multiple endocrine neoplasia syndrome type 2, with bilateral adrenalectomy due to two pheochromocytomas and progressive elevation of urinary metanephrine. Magnetic resonance imaging showed a nodular image in the right adrenal fossa. The patient was referred to our unit in order to confirm suspicion of recurrence. Due to the absence of pathological findings in the (123)I-MIBG scintigraphy and high suspicion of recurrence, PET/CT imaging with (18)F-DOPA and (18)F-FDG were performed, and the diagnosis was confirmed.

[Effectivity and clinical impact of (18)F-FDG-PET in the diagnosis of unsuspected second primary tumors]. / Efectividad e impacto clínico de la PET-(18)F-FDG en el diagnóstico de segundos tumores primarios insospechados.

OBJECTIVE: This study has aimed to determine the capacity and clinical impact of the (18)F-FDG-PET to detect previously unsuspected second primary tumors. MATERIAL AND METHODS: This is a retrospective cross-sectional study of 1984 consecutive scans performed between March 2004 and March 2005, identifying those studies that had reported the presence of hypermetabolic lesions, that had not been previously suspected or detected and that could be suggestive of second primary tumors. Diagnosis was made histopathologically or by clinical and radiological follow-up for a period exceeding one year. RESULTS: 62 findings suggestive of second primary tumors were detected in 58 patients (3.1%). The reasons for the study for this group of patients were diverse, the most common being the differential diagnosis of solitary pulmonary nodules. A total of 43.5% of lesions were not followed-up. We confirmed the existence of 35 lesions, either by pathology study (21 lesions, 13 second primary tumors, the incidence in our population was 0.65%) or clinical and radiological follow-up (14 lesions, none of which corresponded to second primary tumors). The total clinical impact was the discovery of unexpected 14 lesions in 12 patients. CONCLUSION: The presence of second primary tumors on (18)F-FDG-PET is relatively common. These lesions should be monitored clinically for accurate diagnosis. In a high percentage, they correspond to unexpected second primary tumors in an early stage and therefore amenable to curative treatment or for which tumor treatment planning may be modified.

[Evaluation of efficacy and clinical impact of 18F-FDG-PET in the diagnosis of recurrent medullary thyroid cancer with increased calcitonin and negative imaging test]. / Evaluación de la eficacia y del impacto clínico de la PET-18F-FDG en el diagnóstico de recurrencia del carcinoma medular de tiroides con calcitonina elevada y pruebas de imagen negativas.

AIM: To evaluate the efficacy and clinical impact of the FDG-PET in the diagnosis of suspicion of recurrence of medullary thyroid cancer (MTC) in patients with elevated serum calcitonin and negative imaging test. MATERIAL AND METHODS: We performed a retrospective study of 31 consecutive cases from february 2001 to october 2007 of 17 women and 14 men, mean age 56.2 years (range: 26-88), with anatomical-pathology diagnosis of medullary thyroid cancer and suspicion of recurrence due to abnormal elevation of calcitonin and negative imaging tests. All of the patients underwent whole body FDG-PET scan with a dedicated PET or PET-CT 60 minutes after intravenous injection of 333-434 MBq of (18)F-FDG. Results were confirmed by pathology study in 45.2% of the patients and by clinical follow-up with a mean of 4 years (range: 16 m-8 years) RESULTS: Sensitivity was 88%, specificity 84.6%, positive predictive value 88%, negative predictive value 84.6% and diagnostic accuracy 87%. The results of the FDG PET modified the therapeutic strategy in 14 cases (45.2%). A comparison was made of the mean values of calcitonin using the Student's "t" test between positive PET studies for the disease and negative ones. No significant differences were found (P=.3). CONCLUSIONS: In patients with MTC and suspected recurrence with elevated calcitonin and negative imaging test, the FDG is the best test for the diagnosis of occult recurrence in MTC with elevated calcitonin and negative imaging techniques with elevated clinical impact. It facilitates the therapeutic management of the patients with MTC recurrence, and should be included in the diagnosis algorithm in these patients.