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To assess which specific morphologic features, enhancement patterns, or pharmacokinetic parameters on breast Magnetic Resonance Imaging (MRI) could predict a false-negative outcome of Proton MR Spectroscopy (1H MRS) exam in patients with invasive breast cancer. Sixteen patients with invasive ductal carcinoma of the breast were prospectively included and underwent both, contrast-enhanced breast MRI and 1H MRS examination of the breast. The MR images were reviewed and the lesions morphologic features, enhancement patterns and pharmacokinetic parameters (k21-value) were scored according to the ACR BI-RADS-MRI lexicon criteria. For the in vivo MRS studies, each spectrum was evaluated for the presence of choline based on consensus reading. Breast MRI and 1H MRS data were compared to histopathologic findings. In vivo 1H MRS detected a choline peak in 14/16 (88%) cancers. A false-negative 1H MRS study occurred in 2/16 (14%) cancer patients. K21 values differed between both groups: the 14 choline positive cancers had k21 values ranging from 0.01 to 0.20/second (mean 0.083/second), whereas the two choline-negative cancers showed k21 values of 0.03 and 0.05/second, respectively (mean 0.040/second). Also enhancement kinetics did differ between both groups; typically both cancers that were choline-negative showed a late phase plateau (100%), whereas this was only shown in 5/14 (36%) of the choline positive cases. There was no difference between both groups with regard to morphologic features on MRI. This study showed that false-negative 1H MRS examinations do occur in breast cancer patients, and that the presence of a choline peak on 1H MRS as malignancy marker is related to the k21 value of the invasive tumor being imaged. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of coaxial needle size on pneumothorax rate and the diagnostic accuracy of computed tomography (CT)-guided transthoracic needle aspiration biopsy (TNAB) of pulmonary nodules., Materials and Methods: Retrospective review of 846 consecutive CT-guided TNAB procedures was performed. A coaxial approach was implemented in all patients by using an 18- or 19-gauge outer stabilizing needle through which a smaller aspiration needle or automated biopsy gun was inserted for tissue sampling. Univariate and multivariate regression analyses were used to analyze coaxial needle size, age, sex, smoking history, lesion size, use of an automated core biopsy gun, number of needle passes, and frequency of chest tube placement. Sensitivity, specificity, and diagnostic accuracy were calculated for 676 patients with at least 18 months of clinical follow-up., Results: Pneumothorax occurred in 226 of 846 patients. Coaxial needle size and patient age had a significant effect on pneumothorax rate. Pneumothorax occurred in 124 (38%) of 324 patients who underwent procedures with 18-gauge needles and in 121 (23%) of 522 patients who underwent procedures with 19-gauge needles (P <.001). The overall diagnostic accuracy was 96% for procedures performed with 18-gauge needles and 92% for procedures performed with 19-gauge needles, with a sensitivity of 95% and 89% and a specificity of 100% and 99%, respectively. Pneumothorax occurred in 153 patients older than 60 years, in 99 patients 60 years and younger (P <.02), in 90 patients older than 70 years, and in 162 patients younger than 70 years (P <.01). The relationship between pneumothorax rate and age as a continuous distribution was not significant (P <.07), nor were the 50- or 75-year age cutoffs (P <.06 and P <.9, respectively)., Conclusion: Use of a smaller coaxial stabilizing needle produces a substantially decreased risk of pneumothorax with comparable diagnostic accuracy, sensitivity, and specificity for histopathologic diagnosis of pulmonary nodules., (Copyright RSNA, 2003)