Feasibility of ultrafast dynamic magnetic resonance imaging for the diagnosis of axillary lymph node metastasis: A case report

A 74 year old Japanese woman was diagnosed with invasive breast carcinoma. Her axillary lymph node was slightly swollen and had a short-axis diameter of 8 mm, but fine-needle aspiration did not lead to the diagnosis of metastasis. Subsequent 18F-fluorodeoxyglucose positron emission tomography/computed tomography showed no abnormal accumulation on the lymph node. Ultrafast dynamic magnetic resonance imaging yielded a very fast contrast enhancement like that of the primary lesion based on which we suspected lymph node metastasis. To our knowledge, this is the first report that shows that ultrafast imaging has contributed to the diagnosis of axillary lymph node metastasis.

Intravoxel incoherent motion (IVIM) and non-Gaussian diffusion MRI of the lactating breast

•

Breastfeeding significantly affects IVIM and non-Gaussian diffusion parameters.

•

The distribution of ADC₀ values becomes more heterogeneous after breastfeeding.

•

Care needs to be taken in interpreting DWI data in lactating breasts.

Purpose

To investigate the effect of breastfeeding on IVIM and non-Gaussian diffusion MRI in the breast.

Materials and methods

An IRB approved prospective study enrolled seventeen volunteers (12 in lactation and 5 with post-weaning, range 31–43 years; mean 35.4 years). IVIM (f_IVIM and D*) and non-Gaussian diffusion (ADC₀ and K) parameters using 16 b values, plus synthetic apparent diffusion coefficients (sADCs) from 2 key b values (b = 200 and 1500 s/mm²) were calculated using regions of interest. ADC₀ maps of the whole breast were generated and their contrast patterns were evaluated by two independent readers using retroareolar and segmental semi-quantitative scores. To compare the diffusion and IVIM parameters, Wilcoxon signed rank tests were used between pre- and post-breastfeeding and Mann-Whitney tests were used between post-weaning and pre- or post-breastfeeding.

Results

ADC₀ and sADC values significantly decreased post-breastfeeding (1.90 vs. 1.72 × 10⁻³ mm²/s, P < 0.001 and 1.39 vs. 1.25 × 10⁻³ mm²/s, P < 0.001) while K values significantly increased (0.33 vs. 0.44, P < 0.05). f_IVIM values significantly increased after breastfeeding (1.97 vs. 2.97%, P < 0.01). No significant difference was found in D* values. There was significant heterogeneity in ADC₀ maps post-breastfeeding, both in retroareolar and segmental scores (P < 0.0001 and =0.0001).

Conclusion

IVIM and non-Gaussian diffusion parameters significantly changed between pre- and post-breastfeeding status, and care needs to be taken in interpreting diffusion-weighted imaging (DWI) data in lactating breasts.