Effect of thyroid shielding during mammography: measurements on phantom and patient as well as estimation with Monte Carlo simulation.

BACKGROUND: During mammography, the thyroid is exposed to scattered radiation from breast tissue and the device. This may increase the risk of radiation induced thyroid cancer. METHODS: We investigated the scatter radiation exposition of the thyroid and the effect of a tailored thyroid protection in phantom and patient as well as by using Monte Carlo simulation (MCS). The protective effect of a modified thyroid protection, the relevance of the protective effect and acceptance by patients have been investigated. RESULTS: Phantom and patient measurements provided higher values for the surface dose at thyroid position than expected from MCS (phantom 0.32 mGy; patients 0.38 mGy; MCS 0.16 mGy). Phantom measurements indicated scatter contributions from both breast tissue and collimator/tube system. The value found in our patient study is within the range of the literature (0.22-0.39 mGy). The thyroid protection significantly reduced the surface dose but the dose (0.016 mGy) was higher than that expected from the lead equivalent value. However, the impact of the collar to the effective dose was small (< 4%). The collar was not visible on mammograms. CONCLUSIONS: Scatter from the collimator/tube system contributed with 50% to the thyroid dose. Due to the relative small fraction of dose deposited in the thyroid when compared to the mean glandular dose to the breast, a collar is not mandatory in general. Not being associated with the risk of obscuring parts of mammograms, such a collar may be used for young women considering their higher radio sensitivity.

First International Consensus Conference on lesions of uncertain malignant potential in the breast (B3 lesions).

The purpose of this study is to obtain a consensus for the therapy of B3 lesions. The first International Consensus Conference on lesions of uncertain malignant potential in the breast (B3 lesions) including atypical ductal hyperplasia (ADH), flat epithelial atypia (FEA), classical lobular neoplasia (LN), papillary lesions (PL), benign phyllodes tumors (PT), and radial scars (RS) took place in January 2016 in Zurich, Switzerland organized by the International Breast Ultrasound School and the Swiss Minimally Invasive Breast Biopsy group-a subgroup of the Swiss Society of Senology. Consensus recommendations for the management and follow-up surveillance of these B3 lesions were developed and areas of research priorities were identified. The consensus recommendation for FEA, LN, PL, and RS diagnosed on core needle biopsy or vacuum-assisted biopsy (VAB) is to therapeutically excise the lesion seen on imaging by VAB and no longer by open surgery, with follow-up surveillance imaging for 5 years. The consensus recommendation for ADH and PT is, with some exceptions, therapeutic first-line open surgical excision. Minimally invasive management of selected B3 lesions with therapeutic VAB is acceptable as an alternative to first-line surgical excision.

Assessment of dynamic contrast enhancement of the small bowel in active Crohn's disease using 3D MR enterography.

PURPOSE: To retrospectively compare the dynamic contrast enhancement of the small bowel segments with and without active Crohn's disease at 3D MR enterography (MRE). MATERIALS AND METHODS: Thirteen patients (five men, eight women; mean age 41.2 years; range 29-56) were imaged on a 1.5-T MR scanner (Sonata, Siemens Medical) with standard MR sequences after having ingested 1000 ml of a 3% mannitol solution. Subsequently, high resolution 3D gradient-echo (volumetric interpolated breath-hold examination=VIBE) data sets were obtained pre-contrast and 20-40s, 60-80s, and 120-140 s after i.v. Gd-DOTA administration (0.2 mmol/kg). Signal enhancement was measured on single slices both in normal and histologically confirmed (12/13) inflamed small bowel wall segments as well as in the aorta, the psoas muscle, and the background to calculate signal-to-noise (SNR) and contrast-to-noise ratios (CNR). RESULTS: Small bowel wall enhancement was significantly higher (p<0.05) in inflamed compared to normal segments at 20-40s (SNR inflamed: 58.7+/-33.8 vs normal: 36.0+/-19.8; p=0.048; CNR inflamed: 34.8+/-23.4 vs normal: 16.3+/-11.2; p=0.017) and at 60-80s (SNR: 60.3+/-25.1 vs 41.9+/-20.0; p=0.049; CNR: 34.9+/-15.1 vs 19.3+/-13.2; p=0.01) after i.v. contrast administration, respectively. Even at 120-140 s CNR was still increased in inflamed segments (33.7+/-16.0 vs 18.1+/-13.2; p=0.04), while differences in SNR did not attain statistical significance (63.0+/-26.2 vs 45.3+/-23.3; p=0.15). CONCLUSION: In active Crohn's disease, histologically confirmed inflamed small bowel wall segments demonstrate a significantly increased early uptake of gadolinium on 3D VIBE sequences compared to normal small bowel segments.

Sensitivity and specificity of spinal inflammatory lesions assessed by whole-body magnetic resonance imaging in patients with ankylosing spondylitis or recent-onset inflammatory back pain.

OBJECTIVE: To determine the diagnostic utility of different spinal inflammatory lesions assessed by whole-body magnetic resonance imaging (MRI) in patients with ankylosing spondylitis (AS) or with recent-onset inflammatory back pain (IBP) compared with healthy controls. METHODS: We scanned 35 consecutive patients with AS fulfilling the modified New York criteria, 25 patients with IBP of <24 months' duration (both groups were age < or =45 years and had a Bath Ankylosing Spondylitis Disease Activity Index score > or =4), and 35 healthy age- and sex-matched volunteers using whole-body MRI STIR sequences of the spine. MRIs were independently assessed in random order by 3 readers blinded to patient identity. Inflammatory spinal lesions were recorded consistent with definitions proposed by the Canada/Denmark International MRI Working Group: vertebral corner inflammatory lesions (CIL) and noncorner inflammatory lesions in central sagittal slices and lateral inflammatory lesions (LIL) in lateral slices. Concordantly scored lesions for the 3 possible reader pairs were used in the analysis of sensitivity, specificity, likelihood ratios (LRs), and areas under the curve for the entire spine and by spinal segment. RESULTS: Diagnostic utility was optimal when > or =2 CIL were recorded (for patients with AS, values for sensitivity, specificity, and positive LR were 69%, 94%, and 12, respectively, and for patients with IBP were 32%, 96%, and 8, respectively). LIL had high specificity (97%) but low sensitivity (31%). Nine controls had > or =1 CIL, but only 2 controls had >2 CIL. CONCLUSION: Diagnostic utility of STIR MRI for AS is optimal when > or =2 CIL are present. A single CIL can be found in up to 26% of healthy individuals.