Sang-Wook Yoon

Patient selection guidelines in MR-guided focused ultrasound surgery of uterine fibroids: a pictorial guide to relevant findings in screening pelvic MRI

Uterine leiomyomas (fibroids), the most common benign tumor in women of childbearing age, can cause symptoms including dysmenorrhea, menorrhagia, urinary symptoms, pain and infertility. Hysterectomy is a common approach to treating uterine fibroids, and less invasive surgical approaches such as myomectomy and uterine artery embolization also have been shown to alleviate symptoms. Magnetic resonance-guided focused ultrasound surgery (MRgFUS) is the only totally non-invasive surgical approved method for treating uterine fibroids. In clinical trials, MRgFUS resulted in significant relief of uterine fibroid symptoms. The safe and effective use of MRgFUS is affected by fibroid type and location, position relative to adjacent anatomical structures and the presence of co-existent pelvic disease. Additionally, successful outcomes with MRgFUS have been correlated with the volume of fibroids ablated during the procedure. Thus, selection of patients in whom sufficient fibroid volumes can be treated safely using the MRgFUS system is critical for successful outcomes. The MR images in this pictorial essay provide examples of uterine fibroids for which MRgFUS should be considered and is designed to facilitate the selection of patients for whom MRgFUS is most likely to provide sustained symptom relief.

Predisposing factors of bile duct injury after transcatheter arterial chemoembolization (TACE) for hepatic malignancy.

AbstractThe purpose of this study was to investigate the predisposing factors of bile duct injury after transcatheter arterial chemoembolization (TACE) for treatment of hepatic malignancy. For patients (n = 31) with TACE-related bile duct injuries during a 36-month period, final diagnoses of the tumor, the liver profile, presence of portal vein thrombosis, total number and mode of the TACE just before the development of bile duct injury were compared, respectively with those of patients without bile duct injury n = 234) after TACE. The incidence of bile duct injury was higher in the patients with non-hepatocellular tumors than in patients with hepatocellular carcinoma (p <0.01), and higher in Child-Pugh class A patients than in B or C patients (p <0.01). Segmental or subsegmental TACE tended to induce bile duct injury more frequently than the proximal TACE (p = 0.01). Portal vein thrombosis, the total number of TACEs, total amount of iodized oil, and the usage of gelatin sponge were not closely related to bile duct injuries after TACE (p >0.05). It was concluded that the chance of bile duct injury after TACE is increased in non-cirrhotic livers with good liver profile and to the more selective embolization of distal arterial branches.

Radiologic findings of gastrointestinal tract involvement in hepatocellular carcinoma.

Purpose The purpose of this work was to evaluate the radiologic findings of gastrointestinal (GI) tract involvement in hepatocellular carcinoma (HCC) and to discuss mechanisms of spread. Method Eighteen patients with histologically proven GI tract metastasis in HCC for 4.5 years underwent CT and five also underwent upper GI (UGI) series. The cases were classified according to the mode of spread, based on the radiologic findings. Results The involved portion of the GI tract was the stomach (n = 11), duodenum (n = 4), and colon (n = 4). The mode of spread was direct invasion from a contiguous primary tumor (n = 12), hematogenous metastasis (n = 3), peritoneal seeding (n = 1), and undetermined (n = 2). In cases of direct invasion from contiguous primary tumors, CT revealed GI tract invasion directly from bulky hepatic masses (n = 9) or daughter masses at the portion of the bowel wall contiguous to the hepatic masses (n = 3). In cases of hematogenous spread, CT revealed an intramural mass in the stomach and duodenum (n = 2) or a diffuse thickening of the wall of the stomach (n = 1). In the case of peritoneal seeding, CT revealed multiple small nodules in the right paracolic gutter, omentum, and mesentery with invasion to the colon. Conclusion GI tract involvement in HCC shows various radiologic findings according to the mode of spread, but the most common finding is direct invasion of the stomach, duodenum, or colon from contiguous primary tumor. Index Terms: Computed tomography—Gastrointestinal tract—Gastrointestinal tract, neoplasms—Liver, neoplasms.

Successful use of magnetic resonance–guided focused ultrasound surgery to relieve symptoms in a patient with symptomatic focal adenomyosis

OBJECTIVE To report a successful treatment of symptomatic adenomyosis using magnetic resonance-guided focused ultrasound surgery (MRgFUS). DESIGN Case study. SETTING General hospital. PATIENT(S) A 47-year-old premenopausal woman with focal symptomatic adenomyosis. INTERVENTION(S) MRgFUS. MAIN OUTCOME MEASURE(S) Score on the Uterine Fibroids Symptoms Quality of Life (UFS-QOL) questionnaire and the degree of menstrual pain. RESULT(S) Uterine Fibroids Symptoms reduced from 53 to 28 and the degree of menstrual pain reduced from 10 to 5. CONCLUSION(S) For adenomyosis patients who wish to preserve their uterus, MRgFUS may be a promising alternative to hysterectomy. Additional studies of the safety and efficacy of MRgFUS in this indication should be conducted.

Comparison of image quality and radiation dose between combined automatic tube current modulation and fixed tube current technique in CT of abdomen and pelvis

Background Tube current is an important determinant of radiation dose and image quality in X-ray-based examination. The combined automatic tube current modulation technique (ATCM) enables automatic adjustment of the tube current in various planes (x-y and z) based on the size and attenuation of the body area scanned. Purpose To compare image quality and radiation dose of the ATCM with those of a fixed tube current technique (FTC) in CT of the abdomen and pelvis performed with a 16-slice multidetector row CT. Material and Methods We reviewed 100 patients in whom initial and follow-up CT of the abdomen and pelvis were performed with FTC and ATCM. All acquisition parameters were identical in both techniques except for tube current. We recorded objective image noise in liver parenchyma, subjective image noise and diagnostic acceptability by using a five-point scale, radiation dose, and body mass index (BMI, kg/m2). Data were analyzed with parametric and non-parametric statistical tests. Results There was no significant difference in image noise and diagnostic acceptability between two techniques. All subjects had acceptable subjective image noise in both techniques. The significant reduction in radiation dose (45.25% reduction) was noted with combined ATCM (P < 0.001). There was a significant linear statistical correlation between BMI and dose reduction (r = –0.78, P < 0.05). Conclusion The ATCM for CT of the abdomen and pelvis substantially reduced radiation dose while maintaining diagnostic image quality. Patients with lower BMI showed more reduction in radiation dose.

Transient peritumoral enhancement during dynamic MRI of the liver: cavernous hemangioma versus hepatocellular carcinoma.

Purpose The purpose of this work was to compare the incidence and pattern of transient peritumoral parenchymal enhancement for cavernous hemangioma and hepatocellular carcinoma during dynamic MRI of the liver. Method Two hundred seven hemangiomas and 155 hepatocellular carcinomas up to 4 cm in size were retrospectively assessed. The peritumoral enhancement was comparatively analyzed in terms of the shape, extent, signal intensity, and dependence on the size and degree of contrast enhancement of each tumor. Results For small lesions (<2 cm), hemangiomas (16/141; 11.3%) showed a higher incidence (p = 0.026) of peritumoral enhancement than hepatocellular carcinomas (3/87; 3.5%). For larger lesions (2–4 cm), there was no significant difference (p > 0.05) in the incidence of peritumoral enhancement of hemangiomas (15/66; 22.7%) and hepatocellular carcinomas (15/68; 22.1%). Nineteen (61.3%) of the 31 hemangiomas showed contrast agent filling the entire tumor volume at the phase of peritumoral enhancement. Conclusion In spite of the limited specificity, for a <2 cm small focal lesion with homogeneous contrast enhancement on early phase dynamic MR images in the liver, peritumoral enhancement could suggest a higher possibility of hemangioma rather than hepatocellular carcinoma.

Short-term results of magnetic resonance imaging-guided focused ultrasound surgery for patients with adenomyosis: symptomatic relief and pain reduction

The objective of this study was to evaluate the degree of symptomatic relief obtained after treatment with magnetic resonance-guided focused ultrasound surgery in patients with adenomyosis. Quality of life and pain assessment questionnaires from 35 women, collected on the day of treatment and up to 6 months after treatment, indicated that the treatment was safe and there was a significant reduction in symptoms.

Eosinophilic hepatic necrosis: magnetic resonance imaging and computed tomography comparison.

Objective: To compare the findings of magnetic resonance (MR) imaging with those of computed tomography (CT) of focal liver lesions related to peripheral eosinophilia. Methods: For 12 patients with peripheral eosinophilia (>7%) examined with hepatic MR imaging and CT, 52 focal hepatic lesions larger than 0.5 cm, including 31 lesions simultaneously found on the 2 imaging modalities, were subjected to a comparative analysis of their imaging features. Results: The total number of lesions distinguished from background liver was 39 (75%) on MR imaging and 44 (85%) on CT scans. On arterial phase images of 10 patients with comparable data, homogeneously hyperintense lesions were demonstrated more frequently (P = 0.006) on MR imaging (16 [50%] of 32 lesions) than on CT scans (4 [13%] of 32 lesions). Only 7 (22%) of the 32 hypoattenuating lesions on portal phase CT were depicted as hypointense lesions on portal phase MR images in 12 patients. On delayed phase images in 8 patients, the number of hyperintense lesions on MR images (9 [56%] of 16) was greater (P = 0.077) than that seen on the CT scans (4 [25%] of 16). Conclusions: For many focal hepatic lesions related to peripheral eosinophilia, dynamic MR imaging more easily demonstrates lesional enhancement on arterial and delayed phases than CT scans. Because of the higher degree of lesional enhancement of MR imaging compared with CT, the lesion-to-liver contrast may not be sufficient to distinguish the lesion from the background liver, resulting in decreased sensitivity of portal phase dynamic MR imaging.

Magnetic resonance imaging-guided focused ultrasound surgery for symptomatic uterine fibroids: estimation of treatment efficacy using thermal dose calculations.

OBJECTIVE To study the correlation between the predicted thermal dose volume (TDV) and the actual ablation volumes in MR-guided focused ultrasound surgery (MRgFUS) for symptomatic uterine fibroids, and to follow up the outcome for 12 months post-treatment. STUDY DESIGN Phase-difference fast spoiled gradient-echo MR images were used to analyze thermal change during the energy deliveries of MRgFUS in 60 consecutive patients treated for symptomatic uterine fibroids. The TDV obtained through analysis of these MR images was compared with the non-perfused volume (NPV) measured on post-treatment contrast enhanced T1-weighted images. Final values of TDV ratio and NPV ratio were obtained by dividing these values by original fibroid volume. Patients were followed for 12 months post-treatment to assess symptomatic relief using the symptom severity score (SSS). RESULTS Treatments in which we managed to reach a TDV ratio larger than 27% of the treated fibroid yielded a ratio of NPV to TDV of 1.1±0.5, indicating accurate control of the non-invasive procedure. Patient symptoms, as measured by the SSS, continuously decreased from a mean baseline score of 50±22 to 19±12 (P<0.0001) 12 months post-treatment. CONCLUSIONS At large treatment volumes (exceeding 27% TDV ratio), thermal dose estimates correspond very closely to non-perfused volumes measured immediately post treatment. These large treatment volumes result in continuous clinical improvement throughout the first 12 months after MRgFUS.

Contrast-Enhanced Dynamic MR Imaging of Uterine Fibroids as a Potential Predictor of Patient Eligibility for MR Guided Focused Ultrasound (MRgFUS) Treatment for Symptomatic Uterine Fibroids

Magnetic resonance-guided focused ultrasound surgery (MRgFUS) is a non-invasive treatment approach for symptomatic uterine fibroids. One imaging characteristic considered in selecting patients who may benefit from MRgFUS of their uterine fibroids is the signal intensity of the fibroid compared with surrounding myometrium on T2-weighted MR images. Previous reports suggest that hyper-intense fibroids are less amenable to MRgFUS compared with iso- or hypo-intense fibroids. In this case study, we utilized contrast-enhanced dynamic MR imaging to further characterize the vascularity of a hyper-intense fibroid. Based on the results of dynamic T1-weighted contrast-enhanced images, we assumed that the hyper-intense appearance resulted from high fluid content rather than high vascularity and predicted that the fibroid would respond to MRgFUS. The patient underwent the MRgFUS without complication and reported significant decrease in fibroid symptoms at 3 and 12 months post-treatment. This case suggests that pre-treatment dynamic contrast-enhanced imaging used in conjunction with T2-weighted imaging may improve the criteria for selecting uterine fibroids amenable to treatment with MRgFUS, potentially leading to improved patient outcomes.