Maximum tumor-absorbed dose measured by voxel-based multicompartmental dosimetry as a response predictor in yttrium-90 radiation segmentectomy for hepatocellular carcinoma.

OBJECTIVE: Advances in hepatic radioembolization are based on a selective approach with radical intent and the use of multicompartment dosimetric analysis. The objective of this study is to assess the utility of voxel-based dosimetry in the quantification of actual absorbed doses in radiation segmentectomy procedures and to establish cutoff values predictive of response. METHODS: Ambispective study in hepatocarcinoma patients treated with radiation segmentectomy. Calculated dosimetric parameters were mean tumor-absorbed dose, maximum tumor AD, minimal tumor AD in 30, 50, and 70% of tumor volume and mean AD in non-tumor liver. The actual absorbed dose (aAD) was calculated on the Y-90-PET/CT image using 3D voxel-based dosimetry software. To assess radiological response, localized mRECIST criteria were used. The objective response rate (ORR) was defined as CR or PR. RESULTS: Twenty-four HCC patients, BCLC 0 (5), A (17) and B (2) were included. The mean yttrium-90 administered activity was 1.38 GBq in a mean angiosome volume of 206.9 cc and tumor volume 56.01 cc. The mean theoretical AD was 306.3 Gy and aAD 352 Gy. A very low concordance was observed between both parameters (rho_c 0.027). ORR at 3 and 6 m was 84.21% and 92.31%, respectively. Statistically significant relationship was observed between the maximum tumor-absorbed dose and complete radiological response at 3 m (p 0.022). CONCLUSION: A segmental approach with radical intention leads to response rates greater than 90%, being the tumor maximum absorbed dose the dosimetric parameter that best predicts radiological response in voxel-based dosimetry.

Relevance of [18F]FDG-PET/CT in the detection of colon pathology, in patients studied by bacteriemia or infectious endocarditis caused by enteropathogenic microorganisms.

PURPOSE: Association between S. gallolyticus infective endocarditis (IE) and malignant lesions of the gastrointestinal tract is well described. We hypothesize that other enteropathogenic microorganisms, such as S. viridans and E. faecalis are also related with colorectal pathology. Our aim is to determine the frequency of focal colorectal FDG deposits, suggestive of tumoral lesions and their correlation with colorectal pathology, in patients with infection caused by different commensal microorganisms of the gastrointestinal tract. METHODS: We retrospectively examined 61 patients diagnosed with bacteremia (BSI) and IE (possible or definite) according to Duke's criteria, caused by enteropathogenic microorganisms, who underwent a full-body [18F]FDG-PET/CT in our institution. We looked for colorrectal FDG deposits and morphological lesions. All IE patients underwent a complete colonoscopy and the histological results were classified into four groups: malignant lesion, premalignant lesion, benign lesion and no lesion. We evaluated the correlation between the findings of the [18F]FDG-PET/CT with the histopathological diagnosis and the involved microorganism. RESULTS: PET/CT detected 20 colorectal FDG deposits (32.79%-OR: 47.28), 2 within bacteriemic patients (16.7%) confirmed as malignant and premalignant lesions and 18 in IE group (36.6%), 17 of them corresponding to colorrectal pathology: 11 malignant, 5 premalignant and 1 benign lesions. In the IE subgroup, the colonoscopy detected colorectal lesions in 51.02% of the patients: 11malignant, 8premalignant and 6benign. We found a higher incidence of colorectal FDG deposits in Streptococcus spp. subgroup. Regarding the anatomopathological colonic findings there was a predominance of patients affected by S. viridans, followed by E. faecalis and S. gallolyticus. CONCLUSION: Patients studied by PET/CT for systemic infection, especially IE, caused by S. viridans or E. faecalis, in addition to S. gallolyticus, show a greater probability of presenting incidental colorectal FDG deposits, mostly corresponding to malignant or pre-malignant lesions. Therefore, it is necessary to carry out an exhaustive search of possible colorectal foci in these exams.

Small rounded B-cell lymphoma of bone presented by limp, with a positive multifocal 99mTc MDP bone scintigraphy pattern and a negative 99mTc HMPAO-labeled leukocytes study.

In this article, we present a rare case of B-cell bone lymphoma in a child with multifocal asymptomatic lesions detected by bone scintigraphy and a chronic clinical history characterized by limping and fever episodes for over a year. Initially, multifocal osteomyelitis was suspected and antibiotic therapy was administered with no clinical improvement. The biopsy of the main lesion in the left distal femur along with bone marrow cytology established the final diagnosis. This rare case illustrates the utility of routinely low cost-effective nuclear medicine studies like whole body bone scan and 99mTc hexamethylpropyleneamine oxime-labeled leukocytes to orientate similar cases to a correct diagnosis.