The role of 18F-FDG PET/CT imaging in paediatric Langerhans disease: Case report.

Langerhans cell histiocytosis (LCH) is a haematological disorder, affecting single or multiple organs, characterized by abnormal proliferation of Langerhans cells in children. Accurate tumour delineation (number of lesions, organs involved) is crucial for staging/re-staging, and follow-up (response to therapy). Conventional imaging techniques (computed tomography (CT), magnetic resonance imaging (MRI)) have been employed for initial diagnosis, staging and assessment of response to therapy focusing on the healing effect therapeutic protocols have on the disease. In this case report, whole-body positron emission tomography/computed tomography (PET/CT) was shown either to provide information on the metabolic activity of histiocytes, or identify lesions otherwise asymptomatic. It is clear that PET/CT, combining anatomic and metabolic information, provides data for accurate staging, therapeutic protocol selection and assessment of response to therapy.

Common and Uncommon Artifacts in T1 FLAIR SAG Sequences of MRI Brain.

OBJECTIVE: This study aims at identifying, classifying, and measuring the frequency the different artifacts that show up in the images of the Sagittal T1 Fluid Attenuated Inversion Recovery (FLAIR) sequence. MATERIALS AND METHODS: A total of 101 subjects underwent brain magnetic resonance imaging examination with the following sequences: Axial T1 FLAIR, Axial T2-weighted imaging, Diffusion Weighted Imaging, 2D Multiple Echo Recombined Gradient Echo, Sagittal T1 FLAIR, Coronal T2 Turbo Spin Echo, Spin Echo T1-weighted imaging, and 3D Fast Spoiled Gradient-echo. In these images, we observed the following categories of artifacts: (a) ghost artifacts, (b) aliasing behind the occipital bone, (c) aliasing inside the sphenoid cavity, (d) susceptibility artifacts, and (e) pulsation artifacts. In order to recognize and verify the artifacts, we used not only the Sagittal T1 FLAIR sequence, but also Sagittal reconstructions from the 3-dimensional Fast Spoiled Gradient-echo sequence and the other routine sequences. RESULTS: Aliasing artifacts and especially aliasing of nose are present in 41% of the cases. In 45% of these cases the uncommon aliasing artifacts, which took place into the brain parenchyma (sphenoid cavity, subarachnoid bay, or pituitary) originated from nose. In 33% of the subjects, ghost artifacts are presented, which stem from the nose, the orbits, or other pulsating structures (pulsation artifacts) or even from fat tissue. Moreover, susceptibility artifacts comprise 8% of all the artifacts. Finally, 19% of brains were presented without artifact. CONCLUSIONS: We suggest in addition to T1 FLAIR, the application of Sagittal SE or TSE sequences in magnetic resonance imaging examination of brain, trying to include the nose in the square of FOV.

Leydig cell tumour of the ovary localised with positron emission tomography/computed tomography.

Androgen-producing ovarian tumours can lead to assessment difficulties because of their small size. We present a case of virilising steroid cell ovarian tumour in a 41-year-old woman localised with Fluorine-18-Deoxyglucose Positron Emission Tomography/Computed Tomography ((18)FDG-PET/CT). Although the biochemical evaluation pointed to an ovarian source of androgen, diagnostic attempts to localise the source of hyperandrogenism with transvaginal ultrasound (US), and magnetic resonance imaging (MRI) of pelvis failed. Additional evaluation with (18)FDG-PET/CT showed an increased uptake in the right ovary. A laparoscopic right oophorectomy was performed and histopathology examination revealed a 1.2-cm Leydig cell tumour. The patient showed regression of clinical signs.

Patient-specific dosimetry in predicting renal toxicity with (90)Y-DOTATOC: relevance of kidney volume and dose rate in finding a dose-effect relationship.

UNLABELLED: Nephrotoxicity is the major limiting factor during therapy with the radiolabeled somatostatin analog (90)Y-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-d-Phe(1)-Tyr(3)-octreotide (DOTATOC). Pretherapeutic assessment of kidney absorbed dose could help to minimize the risk of renal toxicity. The aim of this study was to evaluate the contribution of patient-specific adjustments to the standard dosimetric models, such as the renal volume and dose rate, for estimating renal absorbed dose during therapy with (90)Y-DOTATOC. In particular, we investigated the correlation between dose estimates and effect on renal function after therapy. METHODS: Eighteen patients with neuroendocrine tumors (9 men and 9 women; median age, 59 y) underwent treatment with (90)Y-DOTATOC (8.1-22.9 GBq) after pretherapeutic biodistribution study with (86)Y-DOTATOC. Kidney uptake and residence times were measured and the absorbed dose (KAD) was computed using either the MIRDOSE3.1 software assuming a standard kidney volume (KAD(StdVol)) or the MIRD Pamphlet 19 values and the actual kidney cortex volume determined by pretherapeutic CT (KAD(CTVol)). For each patient, the biologic effective dose (BED) was calculated according to the linear quadratic model to take into account the effect of dose rate and fractionation. Renal function was evaluated every 6 mo by serum creatinine and creatinine clearance (CLR) during a median follow-up of 35.5 mo (range, 18-65 mo). The individual rate of decline of renal function was expressed as CLR loss per year. RESULTS: KAD(CTVol) ranged between 19.4 and 39.6 Gy (mean, 28.9 +/- 5.34 Gy). BED, obtained from KAD(CTVol), ranged between 27.7 and 59.3 Gy (mean, 40.4 +/- 10.6 Gy). The CLR loss per year ranged from 0% to 56.4%. In 12 of 18 patients, CLR loss per year was <20%. No correlation was observed between CLR loss per year and the KAD(StdVol) or the KAD(CTVol). In contrast, BED strongly correlated with CLR loss per year (r = 0.93; P < 0.0001). All 5 patients with CLR loss per year >20% received a BED >45 Gy. Patients who were treated with low fractionation were those with the highest rate of renal function impairment. CONCLUSION: Radiation nephrotoxicity after (90)Y-DOTATOC therapy is dose dependent. Individual renal volume, dose rate, and fractionation play important roles in an accurate dosimetry estimation that enables prediction of risk of renal function impairment.