Takao Igarashi

Breast MRI Using the VIBE Sequence: Clustered Ring Enhancement in the Differential Diagnosis of Lesions Showing Non-Masslike Enhancement

OBJECTIVE The purpose of this study was to assess the frequency of a finding in which minute ring enhancements are clustered (defined as clustered ring enhancement) in lesions showing non-masslike enhancement and to evaluate the clinical usefulness of this sign, in addition to that of the BI-RADS MRI descriptors, in the differentiation between benign and malignant lesions. MATERIALS AND METHODS Retrospective review was performed of 61 consecutive lesions showing non-masslike enhancement. MRI was performed on a 1.5-T system using the volumetric interpolated breath-hold examination (VIBE) sequence. The kinetic parameter was visually assessed as follows: washout, plateau, and persistent. RESULTS The most frequent morphologic finding among the malignant lesions was heterogeneous internal enhancement (69%) (p = 0.003), followed in frequency by segmental distribution (54%) (p < 0.001); whereas, stippled internal enhancement was the most frequent finding in benign lesions (50%) (p < 0.001). The presence of clustered ring enhancement was found in 63% of the malignant lesions and only 4% of the benign lesions (p < 0.001). The features with the highest positive predictive value for malignancy were a segmental distribution (100%), clustered ring enhancement (96%), and a washout pattern (94%). The specificity of clustered ring enhancement was 96% (25/26). In cases showing focal and regional enhancement, the combination of clumped internal architecture and clustered ring enhancement showed a statistically significant association with malignant lesions (p < 0.001). CONCLUSION Clustered ring enhancement is thought to be a useful sign to differentiate between benign and malignant lesions, in addition to the BI-RADS MRI descriptors.

Use of BI-RADS-MRI descriptors for differentiation between mucinous carcinoma and fibroadenoma.

OBJECTIVE We evaluated the latest breast imaging reporting and data system (BI-RADS) magnetic resonance imaging (MRI) (5th edition) descriptors and non BI-RADS MRI factors that contribute to differentiation between mucinous carcinomas (MCs) and fibroadenomas (FAs). MATERIALS AND METHODS This retrospective study included 27 patients with P-MCs or M-MCs similar to P-MCs and 22 patients with FAs who underwent breast MRI between October 2008 and July 2014 at our institution. Definitive histopathological diagnoses were made for all of the MCs and FAs. The latest BI-RADS MRI descriptors for abnormal enhancement, including maximum diameter, shape (irregular or round/oval), margin (irregular or circumscribed), rim enhancement (present or absent), dark internal septation (absent or present), delayed internal enhancement (heterogeneous or homogeneous), and the time-intensity curve pattern (not persistent or persistent) were evaluated. As additional non BI-RADS MRI factors related to differentiation between MC and FA, age, signal intensity in the T2-weighted image (high or not high), extent of lobulation (strong or weak), enhancing internal septation (present or absent), and the apparent diffusion coefficient value were also evaluated. One radiologist retrospectively evaluated interpreted MR findings and analyzed the findings. Statistically significant findings were identified through univariate and multivariate analyses. Then, three blinded radiologists reviewed the MR images where MR findings had shown a significant association with outcomes during univariate analyses. Independently, the three blinded readers reviewed the MR images for the evaluation of inter-observer variability, and then arrived at a consensus for the evaluation of observer performance. Observer performance and inter-observer variability were determined via a receiver-operating-characteristic curve analysis and weighted k statistics. The sensitivity, specificity, and accuracy of each of the MR findings were calculated. RESULTS Univariate analyses showed that irregular margins were observed more frequently in MCs than in FAs (11/27, 41% vs. 1/22, 0.5%, p<0.05). MCs also showed rim enhancement, delayed heterogeneous enhancement, and enhancing internal septation more frequently than FAs (p<0.05). FAs showed circumscribed margins more frequently than MCs (21/22, 95% vs. 16/27, 59%, p<0.05). FAs also showed dark internal septation more frequently than MCs (18/22, 82% vs. 3/27, 11%, p<0.05). In multivariate analyses, the most significant feature in lesion characterization was delayed heterogeneous enhancement. In the blinded reading, a combination of irregular margin and delayed heterogeneous enhancement showed the highest sensitivity (96.3%) and accuracy (87.8%). Enhancing internal septation showed the highest specificity (90.9%). The κ values with confidence ratings for differentiation between MCs and FAs were 0.63-0.67, which showed substantial agreement among the three radiologists. CONCLUSIONS The combination of irregular margin and delayed heterogeneous enhancement and enhancing internal septation were significant findings for differentiation between P-MC or M-MC similar to P-MC and FA.

A rare solitary fibrous tumor in the ischiorectal fossa: a case report

BackgroundA solitary fibrous tumor (SFT) is a rare mesenchymal tumor that occurs mostly in pleural sites, and an SFT occurring in the ischiorectal fossa is extremely rare. Because of the rarity, there are few reports detailing an SFT in the ischiorectal fossa.Case presentationA pararectal tumor was incidentally found in a 42-year-old man during a routine medical examination. The patient had no symptoms and no previous medical history. In the physical examination, a smooth-margined and hard elastic mass was felt, and in a digital rectal examination, the rectal mucosa appeared normal. A computed tomography (CT) scan showed a 5-cm, well-defined, solid mass in the left ischiorectal fossa. Contrast-enhanced CT in the early phase showed intense heterogeneous enhancement that persisted during the delayed phase. T2-weighted images of magnetic resonance imaging yielded heterogeneous intermediate and low signal intensity. Intense arterial enhancement suggested a hypervascular nature, and persistent delayed enhancement and low signal bands on T2-weighted images suggested a fibrous component of the mass. An SFT was suspected. Most SFTs are benign but have malignant potential. Our patient did not hope for surgery if the tumor was benign; therefore, an ultrasound-guided transperineal core needle biopsy was performed to decide on a treatment strategy. Microscopic examination showed tumor cells appearing as spindle and fibroblast-like cells within a collagenous stroma. Immunohistochemistry identified CD34 and vimentin, supporting the diagnosis of an SFT. The patient consented to excision of the mass. He was placed in a prone jackknife position, and the tumor was removed transperineally using a posterior approach (modified Kraske procedure). The levator ani muscle, external sphincter muscles, and rectum were not involved and separated from the tumor. The tumor was successfully resected en bloc with no complications. Five uneventful days post surgery, the patient was discharged. There was no local recurrence during the year following surgery.ConclusionImaging findings reflect the tissue characterization such as hypervascularity and fibrous nature of SFTs. We have presented a rare case of an SFT in the ischiorectal fossa with useful imaging findings for diagnosis, treatment strategy, and successful surgical removal using a posterior approach.

Clinical impact of the Sherlock 3CG® Tip Confirmation System for peripherally inserted central catheters

Objective This study was performed to evaluate the technical success rate and catheter tip malposition rate of peripherally inserted central catheter (PICC) placement using the Sherlock 3CG® Tip Confirmation System (TCS). Methods In total, 114 patients who underwent PICC insertion via the Sherlock 3CG® TCS from October 2017 to February 2018 were retrospectively evaluated. The primary endpoints were the technical success rate, malposition rate, and mean procedure time. The secondary endpoints were the sex-related difference in the malposition rate, radiologist’s experience level, and side of insertion. Technical success was defined as procedure completion using only the Sherlock 3CG® TCS without a guidewire or fluoroscopy guidance. In accordance with the North American guidelines, an adequate position was defined as the lower third of the superior vena cava and the cavoatrial junction. Results The technical success rate was 97% (111/114). The malposition rate was 16% (18/111), and four catheters were repositioned. There were no significant differences in the malposition rate between the sexes, radiologist’s level of experience, or side of insertion. Conclusions PICC placement using the Sherlock 3CG® TCS yielded a high technical success rate and low catheter tip malposition rate regardless of the radiologist’s level of experience or side of insertion.

Breast MRI for prediction of lymphovascular invasion in breast cancer patients with clinically negative axillary lymph nodes

OBJECTIVE To retrospectively assess magnetic resonance imaging (MRI) findings that can predict lymphovascular invasion (LVI) in invasive breast cancer patients who were diagnosed with clinically negative axillary lymph nodes (LNs) preoperatively. METHODS This study included 140 lesions of 140 patients who underwent preoperative breast MRI and breast surgery, with omission of axillary LN dissection. Clinical characteristics and MRI findings were evaluated. The T2 signal intensity (SI) ratio (mean T2 SI of the tumor/mean T2 SI of the muscle), tumor apparent diffusion coefficient (ADC) value, peritumoral ADC value, peritumor-tumor ADC ratio (peritumoral maximum ADC value/tumor mean ADC value), and ADC value of the contralateral breast parenchyma were retrospectively assessed. Statistical analyses were performed to identify significant factors for predicting LVI. Inter-observer variability was calculated. RESULTS The tumor ADC value (all ages: p = 0.005; age ≤ 55: p < 0.001), peritumoral ADC value (age ≤ 55: p = 0.04), and peritumor-tumor ADC ratio (all ages: p < 0.001; age ≤ 55: p < 0.001) were significantly associated with LVI on univariate analysis. Multivariate logistic regression analysis revealed significant differences in the pathological size of the invasive component and the tumor ADC value for predicting LVI (odds ratio [OR]: 3.43; 95% confidence interval [CI]: 1.41-8.32; p = 0.007; OR: 16.0; 95% CI: 1.89-136; p = 0.01, respectively). Inter-observer agreement was substantial for the tumor ADC value (intraclass correlation coefficient [ICC] = 0.77; 95% CI: 0.70-0.83) and the ADC value of the contralateral breast parenchyma (ICC = 0.68; 95% CI: 0.59-0.76). There was moderate agreement for the peritumoral ADC value (ICC = 0.53; 95% CI: 0.40-0.64) and the peritumor-tumor ADC ratio (ICC = 0.49; 95% CI: 0.35-0.61) and fair agreement for the T2 SI ratio (ICC = 0.30; 95% CI: 0.15-0.45). CONCLUSION We found that the tumor ADC value, peritumoral ADC value, and peritumor-tumor ADC ratio were predictive MRI findings for LVI in patients aged ≤55. The tumor ADC value was the most significant predictor for LVI; moreover, inter-observer agreement for the tumor ADC value was substantial between two blinded observers with differences in interpretation experience.

Diagnostic value of ultrasonography and TI-201/Tc-99m dual scintigraphy in differentiating between benign and malignant thyroid nodules

PurposeTo evaluate the performance of ultrasonography (US) and TI-201/Tc-99m dual (Tl/Tc) scintigraphy in differentiating between benign and malignant thyroid nodules.MethodsEighty-six patients diagnosed to have a thyroid tumor on postoperative histopathologic examination between June 2009 and February 2017 were included in this retrospective study. A radiologist reviewed the US and Tl/Tc scintigraphy reports along with all available clinical and histopathologic information. On Tl/Tc scintigraphy, a nodule in which uptake was higher in the delayed phase than in the surrounding parenchyma was defined as a delayed accumulation pattern and a nodule in which uptake was higher in the delayed phase than in the early phase was defined as a persistent pattern. The Tl/Tc scintigraphy images were evaluated in a blinded manner to assess reproducibility. A statistical analysis was performed to identify features associated with malignancy. Interobserver variability was calculated using the κ statistic.ResultsUS had higher sensitivity (81.2%), specificity (88.2%), and positive (96.6%) and negative (53.6%) predictive values than Tl/Tc scintigraphy. An ill-defined margin and microcalcification were independent predictors of a malignant thyroid nodule on multivariate logistic regression (P = 0.003 and P = 0.014, respectively). The persistent pattern had high specificity (85.7%) equivalent to that of US but had lower sensitivity (34.7%). The κ values for the delayed accumulation and persistent patterns were 0.66–0.78 and 0.32–0.50, respectively.ConclusionsAn ill-defined margin and microcalcification on US were independent predictors of a malignant thyroid nodule. A persistent pattern seen on Tl/Tc scintigraphy could contribute to the differential diagnosis.

MRI Findings After Cryoablation of Primary Breast Cancer Without Surgical Resection

RATIONALE AND OBJECTIVES To retrospectively evaluate findings on serial magnetic resonance imaging (MRI) after cryoablation for breast cancer lesions without subsequent surgical resection. MATERIALS AND METHODS This study was approved by the Institutional Review Board and the requirement to obtain informed consent waived. Ductal carcinoma in situ or invasive carcinoma ≤15 mm, nuclear grade 1 or 2, estrogen receptor positive/human epidermal growth factor 2 negative without lymph node metastasis were treated with cryoablation without subsequent excision. Two observers independently reviewed the first two postcryoablation MRIs for shape (none, focus-to-mass, or nonmass enhancement) and suspicion of residual disease (positive or negative). Fishers exact or the Mann-Whitney U test was used to assess significance. Interobserver agreement on findings was evaluated by calculating κ values. RESULTS Fifty-four patients were enrolled. The first and second postcryoablation MRIs were performed 22-171 days and 82-487 days after cryoablation, respectively. Interobserver agreement ranged from fair to moderate (κ = 0.356-0.434). Observer 1 or 2 identified suspicious areas on the first postcryoablation MRI in seven cases (13.0%). These were significantly associated with focus-to-mass shape (vs non-focus-to-mass: nonmass enhancement or none) and residual disease or recurrence suspected by both observers (p < 0.001). There were no cases of both observers identifying suspicious findings on the second postcryoablation MRI. CONCLUSION Suspicious findings can be detected within the treated area at the first postcryoablation MRI. These can resolve during subsequent adjuvant therapies and follow-up.