Sachiko Isobe

Kameda Medical Center, Kameda, Niigata, Japan

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Publications (7)8.75 Total impact

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    ABSTRACT: This study compared the diagnostic performance of two shear wave speed measurement techniques in 81 patients with 83 solid breast lesions. Virtual Touch Quantification, which provides single-point shear wave speed measurement capability (SP-SWS), was compared with Virtual Touch IQ, a new 2-D shear wave imaging technique with multi-point shear wave speed measurement capability (2D-SWS). With SP-SWS, shear wave velocity was measured within the lesion ("internal" value) and the marginal areas ("marginal" value). With 2D-SWS, the highest velocity was measured. The marginal values obtained with the SP-SWS and 2D-SWS methods were significantly higher for malignant lesions and benign lesions, respectively (p < 0.0001). Sensitivity, specificity and accuracy were 86% (36/42), 90% (37/41) and 88% (73/83), respectively, for SP-SWS, and 88% (37/42), 93% (38/41) and 90% (75/83), respectively, for 2D-SWS. It is concluded that 2D-SWS is a useful diagnostic tool for differentiating malignant from benign solid breast masses.
    Ultrasound in medicine & biology 09/2013; · 2.46 Impact Factor
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    ABSTRACT: We evaluated the diagnostic performance of elastography and tissue quantification using acoustic radiation force impulse (ARFI) technology for differential diagnosis of breast masses. There were 161 mass lesions. First, lesion correspondence on ARFI elastographic images to those on the B-mode images was evaluated: no findings on ARFI images (pattern 1), lesions that were bright inside (pattern 2), lesions that were dark inside (pattern 4), lesions that contained both bright and dark areas (pattern 3). In addition, pattern 4 was subdivided into 4a (dark area same as B-mode lesion) and 4b (dark area larger than lesion). Next, shear wave velocity (SWV) was measured using virtual touch tissue quantification. There were 13 pattern 1 lesions and five pattern 2 lesions; all of these lesions were benign, whereas all pattern 4b lesions (n = 43) were malignant. When the value of 3.59 m/s was chosen as the cutoff value, the combination of elastography and tissue quantification showed 91 % (83-91) sensitivity, 93 % (65-70) specificity, and 92 % (148-161) accuracy. The combination of elastography and tissue quantification is thought to be a promising ultrasound technique for differential diagnosis of breast-mass lesions.
    Japanese journal of radiology 07/2012; 30(8):659-70. · 0.73 Impact Factor
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    ABSTRACT: The aim of this study was to perform the phantom experiment and demonstrate the clinical usefulness of tissue quantification using a linear array transducer and acoustic radiation force impulse (ARFI) technology. For the phantom study, the commercially available Elasticity QA Phantom Model 049 was used. First, we measured the shear wave velocity (m/s) for the four spheres and the background of the phantom. Then, the shear wave velocity at nine sites was measured, with the region of interest being moved gradually from a shallow region (3 mm) to a deeper region (38 mm). For the clinical study, the shear wave velocities of 15 solid breast mass lesions were measured. The phantom study confirmed the feasibility of quantitative determination of the degree of tissue hardness. Dispersion of the measured values tended to be somewhat increased for the depths of 3 mm and 38 mm. The mean shear wave velocity was 2.07-2.93 m/s for five benign lesions, whereas higher shear wave velocities (n = 2) (7.15, 7.44 m/s) or "X.XX" (unmeasurable state) (n = 7) were found for malignant lesions other than mucinous carcinoma (2.44 m/s). ARFI tissue quantification is a potentially promising ultrasonographic technique for diagnosing breast lesions.
    Japanese journal of radiology 10/2011; 29(8):598-603. · 0.73 Impact Factor
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    ABSTRACT: To investigate the shear wave velocity of normal breast tissue and breast lesion using acoustic radiation force impulse (ARFI) technology. This retrospective study was conducted with the approval of the institutional review board. Shear wave velocity was measured using a linear array transducer with a bandwidth of 4-9 MHz and Virtual Touch tissue quantification (Siemens Medical Solutions, Mountain View, CA, USA) in 50 patients. First, the values of the shear wave velocity were determined in the normal tissues. Then, the changes in the shear wave velocity while applying external compression on the breast were determined. For the differential diagnosis of breast lesions, the shear wave velocities of 30 mass lesions (13 benign and 17 malignant lesions) classified as BI-RADS category 4 were measured. The mean shear wave velocities in the subcutaneous fat and the mammary gland parenchyma were 2.66 m/s and 3.03 m/s, respectively (p=0.0006). The mean shear wave velocity measured while applying external compression was 3.33 m/s for subcutaneous fat (p<0.0001), and 3.84 m/s for the mammary gland parenchyma (p<0.0001). In 4 of malignant cases, the shear wave velocity was not indicated (displayed as X.XX; unmeasurable state). The mean shear wave velocity of the 13 malignant lesions (4.49 m/s) was higher than that of benign lesions (2.68 m/s) (p<0.01). ARFI tissue quantification is thought to be a potentially promising ultrasound technique for the diagnosis of breast lesions, but further investigation is required to identify the most appropriate method of measurement.
    European journal of radiology 07/2011; 80(2):e182-7. · 2.65 Impact Factor
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    ABSTRACT: The aim of this study was to investigate the clinical usefulness of acoustic radiation force impulse (ARFI) imaging for the differential diagnosis of breast lesions. We studied 40 solid mass lesions from a total of 40 patients (age range 29-67 years, mean 50 years). There were 18 benign lesions and 22 malignant tumors. ARFI imaging was performed using Virtual Touch tissue imaging. We examined the possibility of lesions seen on B-mode images being visually confirmed on ARFI images. When the lesion was visually confirmed, the lesions that were bright or dark inside were classified into patterns 1 and patterns 3, respectively. The lesions that failed to be visually confirmed were classified as pattern 2. There were 3 pattern 1 lesions and 7 pattern 2 lesions; all of these lesions were benign. The remaining 8 benign lesions and 22 malignant lesions were determined to be pattern 3. The negative predictive value was 100%. ARFI imaging is a potentially promising ultrasonographic technique for the differential diagnosis of breast lesions, particularly complicated cysts without a cystic component on B-mode images.
    Japanese journal of radiology 07/2011; 29(6):452-6. · 0.73 Impact Factor
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    ABSTRACT: The aims of this study were to investigate the visualization rate for the mammary gland under the nipple with automated breast ultrasonography (US) and to compare the detectability of breast lesions under the nipple with automated breast imaging and handheld US imaging. A total of 60 patients underwent automated breast US (ABVS; Siemens Medical Solutions, Mountain View, CA, USA) and handheld US. The scans of the four segments of the breast included sequential scans in the upper-outer (C), lower-outer (D), lower-inner (B), and upper-inner (A) regions. The visualization rates for the mammary gland under the nipple were 72% (86/120 breasts) in A-scanning, 84% (101/120) in B-scanning, 78% (93/120) in C-scanning, and 80% (96/120) in D-scanning. Interscanning mode differences were statistically significant only for A-scanning and B-scanning (P = 0.02). Eventually, 98% (117/120 breasts) of the breasts examined were rated as "visualized." In 14 of the 15 patients with breast lesions under the nipple, the lesions were detectable with handheld US and the ABVS. In the other patient, the lesion was not detectable on handheld US but was detected on ABVS imaging. ABVS imaging is by no means inferior to handheld US for detecting breast lesions under the nipple.
    Japanese journal of radiology 06/2011; 29(5):361-5. · 0.73 Impact Factor
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    ABSTRACT: The aim of this study was to assess the scanning technique for covering the whole breast using a commercially available automated breast ultrasonography (US) system. A total of 40 patients in the supine position underwent automated breast US (ABVS: Siemens Medical Solutions, Mountain View, CA, USA) and hand-held US. The scanning included sequential scans in the upper-outer, lower-outer, lower-inner, and upper-inner regions. After scanning all four segments of each breast using ABVS, hand-held US was performed in all the patients. The detectability of the lesions using the ABVS technique compared with that using the handheld US was evaluated. The average scanning time was compared between any two of the three examiners with various lengths of experience in breast US. In all, 61 lesions were detected by hand-held US. The average size of the lesions was 7.7 mm (range 2.5-26.0 mm). The number of detected lesions by ABVS was consistent with those found by hand-held US in each patient. The average total scanning time for each examiner using ABVS was 10.9, 11.1, and 11.5 min, respectively. No significant difference was found in the total scanning time between any two of the three examiners. The four-scans technique for the major segments of the breast is thought to be an operator-independent, feasible method for performing automated breast US.
    Japanese journal of radiology 05/2010; 28(4):325-8. · 0.73 Impact Factor