Background: When a palpable breast mass is detected, a biopsy is usually performed even if the mass reveals probably benign morphologic features on imaging, as there is relatively little data reporting the outcome of such breast masses. Purpose: To determine the negative predictive value for sonographic evaluation of palpable breast masses with probably benign morphology, and to assess whether follow-up may be an acceptable alternative to immediate biopsy. Material and Methods: Of the 1399 sonograms of palpable masses from January 2004 to September 2005, there were 397 patients with masses of probably benign morphology. This study included 274 of these patients (age range 12–64 years, mean age 34 years) with 312 palpable masses that were pathologically confirmed by fine-needle aspiration ( n=7), ultrasound (US)-guided core needle biopsy ( n=180), or surgical biopsy ( n=125). The false-negative rate, negative predictive value (NPV), and 95% confidence interval (CI) were calculated using the SPSS statistical software package for Windows, version 12.0. A P value <0.05 was considered statistically significant. Results: Of the 312 masses, there were 310 benign lesions and two malignancies, resulting in a false-negative rate of 0.6% (NPV 99.4%, P value=0.0432, 95% CI 0.0–1.5%). Conclusion: The negative predictive value of sonography for palpable breast masses with probably benign morphology is high (99.4%). Therefore, short-term imaging follow-up can be an acceptable alternative to immediate biopsy, similar to the management of nonpalpable probably benign lesions (BI-RADS category 3).

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This paper proposes a modified volumetric error model that includes spindle error motions as well as geometric errors. The model is constructed using rigid-body kinematics and homogeneous transformation matrices and an additional error matrix describing spindle error motions is included. The suggested model predicts the positioning errors at a given axis position as a function of both the axis position and the engaged spindle rotation angle. Two circular interpolation tests (inner and outer circle of the same radius) are simulated and the machined part profiles are predicted. To verify the simulation results, machining tests are performed according to the ISO 10791-7 standard. The error model with spindle errors shows a better agreement, between the simulated and measured roundness errors, than the simple geometric model. It can be seen that the geometric errors determine the basic part profiles and the spindle errors change the basic profiles according to the magnitude of the errors and the spindle rotation angle.