Medicina nuclear y radioterapia

The impact of irradiation on host-microbe crosstalk is still underexplored. By use of an in vitro oral mucosa model, we show an impact of irradiation on epithelial wound healing depending on the microbial composition and functionality. 454-pyrosequencing analyses pointed to a slight increase in abundance of Rothia, Granulicatella and Gemella in our model after irradiation. Further research is needed to unravel the effects of irradiation on the oral microbiota and the host-microbe interactions more in detail.

We present the case of a 26 year old man who reported persistent pain in his left foot. He had been troubled by this pain for six years but despite previous consultation and investigation the cause of his symptoms had remained elusive.

A magnetic resonance imaging (MRI) scan was performed which hinted at a small area of oedema in the head of the fourth metatarsal. Based on these findings, and working in close conjunction with our specialist radiology colleagues, a CT scan with finer slices was able to identify a 3 mm diameter lucency with a sclerotic central nidus.

Following this challenging diagnosis, the preferred management option was an open resection of the lesion, due to its small size and superficial position. The macro and microscopic appearances of the excised lesion supported the diagnosis of osteoid osteoma, as did the complete resolution of the patient’s symptoms following removal of the offending lesion.

We believe this to be the first case of an isolated osteoid osteoma in the fourth metatarsal ever described in the orthopaedic literature. It highlights the importance of pursuing a diagnosis with the aid of multiple imaging modalities and MRI has again proved its use in the resolution of orthopaedic clinical conundrums.

Objective: To evaluate the acute genitourinary (GU) and gastrointestinal (GI) toxicities, health-related quality of life (HRQOL) factors, biochemical control rates, and technical feasibility of high-dose-rate (HDR) brachytherapy as monotherapy for prostate cancer delivered in a single fraction.

Methods: A single-institution, prospective pilot study evaluating 6 patients with low- and intermediate-risk prostate cancer treated in 2013. Patients received a single 19 Gy fraction as HDR monotherapy. Patients were assessed according to the Common Terminology Criteria for Adverse Events version 4.0, the International Index of Erectile Function (IIEF-5), the International Prostate Symptom Score (IPSS), the Expanded Prostate Cancer Index Composite–Bowel Assessment (EPIC-Bowel), a Quality of Life (QOL) Assessment, and an institutionally designed quality of care (QOC) questionnaire. Biochemical failure was defined as a prostate-specific antigen (PSA) nadir plus 2 ng/ml.

Results: Patients tolerated the implant well and were all discharged home the same day by approximately 4 pm. Median follow-up was 9 months. No grade 3, 4 or 5 toxicities were observed. Two of the 6 patients (33%) experienced grade 2 GU toxicity. One patient (17%) experienced grade 2 GI toxicity. HRQOL bowel and urinary assessments revealed a majority of complaints at 3 months, which returned to baseline at 6 months.

Conclusion: HDR brachytherapy as monotherapy for favorable-risk prostate cancer using one implant delivered in a single 19 Gy dose has acceptable acute toxicities and HRQOL reports similar to alternative treatment options.

Objective: To determine the α/β ratio of prostate cancer using the linear quadratic model taking into account different radiation prescription doses and RBE for low energy gamma rays.

Methods and material: The linear quadratic model was used to evaluate the α/β ratio for prostate cancer taking into account the dosimetric errors resulting from seed displacements in prostate permanent implant brachytherapy with 125I and 103Pd. The study assessed the variability of the α/β ratio with different prescribed external beam radiation therapy doses and published values of the relative biological effectiveness (RBE) for both 125I and 103Pd. The biological effective dose (BED) for prostate implant brachytherapy was equated to the external beam radiation therapy dose to derive an equation for α/β ratio.

Results: The results showed that the α/β ratio for prostate cancer varied between 1 and 4.5 for an RBE of 1.0 when an external beam dose of 78.0 Gy was prescribed. When published values of RBEs were incorporated into the analysis, the α/β ratio varied between 0.37 and 4.4. The α/β ratio changed by 30% when the external beam radiation dose was increased from 72 Gy to 80 Gy.

Conclusions: Assuming an average reduction in implanted seeds brachytherapy dose between 10–20% using 125I or 103Pd, the realistic value of the α/β ratio for prostate tumors likely lies between 0.7 and 2.0.

Bone scan has been widely employed to detect osteoblastic bone metastasis because of the imaging technique’s high sensitivity. However, care should be taken to distinguish false positive bone lesions which result from microcalcification of soft tissue malignancy with real osseous metastasis by correlating other modalities of fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT). We report, for the first time, a patient who was initially diagnosed with stage II left breast infiltrating ductal carcinoma and was under clinical management for 20 years. The patient subsequently presented with thoracic symptoms. Bone scan showed multiple focal uptakes within bilateral thoracic ribs. FDG PET/CT scans, however, showed numerous metabolically active bilateral pulmonary nodules with no osseous lesions in ribs. This case demonstrates abnormal findings on bone scans mimicking metastatic rib lesions from micro-calcified pulmonary metastatic nodules in a patient with breast cancer. Thus, care should be taken to correlate interpretation of high sensitivity but non-specificity bone imaging with other modalities such as FDG PET/CT.

Background: The prognosis is still poor in metastatic Ewing sarcoma (ES) patients. We aimed to assess importance of 18F-PET/CT in 2 pediatric local invasive/ metastatic Ewing sarcoma patients which have been performed antiVEGF and Sorafenib besides their neo-adjuvant and adjuvant chemotherapies (ChT) to improve their prognosis. Response to therapy has been followed by 18F-PET/CT in addition to MR imaging.

Patients: First patient was a 12 year-old-girl who was suffering from right leg pain and diagnosed with Ewing sarcoma (ES). 18F-PET/CT showed a locally invasive mass with 14x5 cm dimensions located on one third of proximal tibia with a 5,1 SUVmax value was observed . After 4 cycles of conventional ChT beside antiVEGFSorafenib, SUVmax: 2,1 and tumor necrosis was 80%. Patient received local Radiotherapy (RT) and still in remission after 18 months. Second patient was a 13 year-old-girl who admitted with swelling and pain on right scapula. MR imaging revealed a mass causing deterioration on right scapula and surrounding soft tissue. Diagnosed as ES. PET/CT showed that: primary lesion SUV max 12,4 value, beside another metastatic lesion on left fifth rib with 3,4 SUVmax,confirmed by MRI and biopsi. In addition to conventional neo-adjuvant ChT regimen for ES, antiVEGF and sorafenib were added. There was no 18F-PET/CT involvement during pre-surgical evaluation. Tumor necrosis was %98 and surgical border was tumor negative. Postoperative adjuvant chemotherapy with antiVEGF and sorafenib continued untill end of the treatment protocol. Besides, local RT. Primary region of the tumor and metastatic lesion were still 18F-PET/CT imaging negative, by the enf of the therapy. Patient is still well after 15 months.

Conclusion: 18F-PET/CT imaging can predict tumor response to neoadjuvant/adjuvant ChT which includes promising antiVEGF and sorafenib therapies in pediatric ES patients in the manner of the primary tumor necrosis ratio and metastatic evaluations.

Secondary hyperparathyroidism is consequent to a chronic hypocalcaemic condition that can be caused primarily by renal failure. As a result of continuous stimulus to produce and secrete PTH induces parathyroid gland hyperplasia. In this case report, we present a chronic renal failure patient with high parathyroid hormon level suspected for secondary hyperparathyroidism. According to the parathyroid scan findings four glands were demonstrated concordant with parathyroid pathology and the patient was operated with intra- operative gamma probe in a very short time. Radio-guided surgery of this renal failure patient by using intra-operative gamma probe for excision of hyperplastic parathyroid glands and hereby shortening the surgery time, provided a positive impact of renal residual function of this dialysis patient. Although, radioguided surgery with minimal invasive surgery is commonly recommended for primary hyperparathyroidism with single adenoma, we recomment radioguided surgery of hyperplastic parathyroid glands especially in renal failure patients for maintaining renal residual function.

Metastatic gallbladder disease is a rare pathology. Gallbladder metastasis of malignant melanoma is especially rarer. Herein we present the solitary metastasis of a malignant melanoma to the gallbladder. 47-year old male having an ulcerated skin lesion at right toe was diagnosed as malignant melanoma with excisional biopsy. Thereon the patient without locoregional disease was treated with large surgical resection. A metastatic inguinal lymph node was excised 4 months later and interferon-alpha treatment was begun. FDG-PET imaging was requested to evaluate the extent of disease after 15 days and any metastatic focus was not detected. A control FDG-PET was performed for the evaluation of therapy 8 months later. There was only an unexpected, markedly increased focal FDG uptake arousing doubt in the gallbladder fossa on the whole-body images. This accumulation was proven histopathologically as malignant melanoma metastasis after exploratory cholecystectomy and the patient was treated by dacarbazine+cisplatin. Physicians interpreting FDG-PET scans of patients with malignant melanoma must be cautious about the significance of prominent unusual uptakes at unexpected localizations. It is mandatory to establish a certain histopathologic diagnosis if possible.