Parametric diffusion tensor imaging of the breast.

OBJECTIVES: To investigate the ability of parametric diffusion tensor imaging (DTI), applied at 3 Tesla, to dissect breast tissue architecture and evaluate breast lesions. MATERIALS AND METHODS: All protocols were approved and a signed informed consent was obtained from all subjects. The study included 21 healthy women, 26 women with 33 malignant lesions, and 14 women with 20 benign lesions. Images were recorded at 3 Tesla with a protocol optimized for breast DTI at a spatial resolution of 1.9 × 1.9 × (2-2.5) mm3. Image processing algorithms and software, applied at pixel resolution, yielded vector maps of prime diffusion direction and parametric maps of the 3 orthogonal diffusion coefficients and of the fractional anisotropy and maximal anisotropy. RESULTS: The DTI-derived vector maps and parametric maps revealed the architecture of the entire mammary fibroglandular tissue and allowed a reliable detection of malignant lesions. Cancer lesions exhibited significantly lower values of the orthogonal diffusion coefficients, λ1, λ2, λ3, and of the maximal anisotropy index λ1-λ3 as compared with normal breast tissue (P < 0.0001) and to benign breast lesions (P < 0.0009 and 0.004, respectively). Maps of λ1 exhibited the highest contrast-to-noise ratio enabling delineation of the cancer lesions. These maps also provided high sensitivity/specificity of 95.6%/97.7% for differentiating cancers from benign lesions, which were similar to the sensitivity/specificity of dynamic contrast-enhanced magnetic resonance imaging of 94.8%/92.9%. Maps of λ1-λ3 provided a secondary independent diagnostic parameter with high sensitivity of 92.3%, but low specificity of 69.5% for differentiating cancers from benign lesions. CONCLUSION: Mapping the diffusion tensor parameters at high spatial resolution provides a potential novel means for dissecting breast architecture. Parametric maps of λ1 and λ1-λ3 facilitate the detection and diagnosis of breast cancer.

Targeted ultrasound is the procedure of choice for detecting rudimentary branchial cysts causing jugular and subclavian vein thrombosis.

The aim of this study was to facilitate the imaging diagnosis of branchial cysts leading to combined jugular and subclavian vein thrombosis during ovarian hyperstimulation syndrome (OHSS). Three women developed combined jugular and subclavian vein thrombosis following OHSS related to assisted reproductive technologies. The imaging modalities used for diagnosis were a bimode Doppler ultrasound, MRI of the neck in two women, computed tomography (CT) angiography and venography in one. Targeted ultrasound identified the rudimentary cysts in all patients, whereas CT angiography performed with contrast material failed to detect the cyst, which resembled a vessel with thrombus in the lumen. MRI performed at the same level did detect the cyst; however, MRI of the neck requires special attention using a dedicated cystic protocol at the base of the neck. Venography was performed in one patient; it demonstrated the thrombosed vein possibly with some extrinsic compression, but it could not define a cyst. Targeted ultrasound is the simplest and best imaging modality for discerning rudimentary cysts in pregnant women with OHSS who present with jugular and subclavian vein thrombosis following assisted reproductive technology. A search for the cyst at the time of OHSS is important, as early detection could decrease the risk of developing thrombosis.

Combined jugular and subclavian vein thrombosis following assisted reproductive technology--new observation.

OBJECTIVE: To study the predilection of jugular and subclavian vein thrombosis in patients going through assisted reproductive technology (ART). This technology puts women at high risk of developing the ovarian hyperstimulation syndrome (OHSS) and thrombotic events. DESIGN: Study cases. SETTING: Large Academic Medical Center. PATIENT(S): Five women who developed jugular and subclavian vein thrombosis following ART were included in the study. INTERVENTION(S): The deep vein thrombosis was demonstrated by ultrasound Doppler or computerized tomography angiography. All women were interviewed and data obtained from outpatient and hospital medical charts. Magnetic resonance imaging and complete thrombophilic profile workup was performed in each woman. Open biopsy from the lesions was taken from one of the women. MAIN OUTCOME MEASURE(S): Correlation between mechanical branchial cysts filled with fluid during OHSS and jugular and subclavian vein thrombosis. RESULT(S): Five women developed jugular and subclavian vein thrombosis following ART. They were found to harbor clusters of rudimentary branchial cysts filled with fluid at the time of OHSS, which compressed the jugular and subclavian veins at their junction at the base of the neck. Four patients (80%) were found to be carriers of factor V Leiden. CONCLUSION(S): Predilection of jugular and subclavian vein thrombosis early in pregnancy is the result of mechanical compression mediated by rudimentary branchial cysts filled with fluid during OHSS, particularly in subjects who are carriers of factor V Leiden.

Strains and stresses in sub-dermal tissues of the buttocks are greater in paraplegics than in healthy during sitting.

A pressure-related deep tissue injury (DTI) is a severe pressure ulcer, which initiates in muscle tissue overlying a bony prominence (e.g. the ischial tuberosities, IT) and progresses outwards through fat and skin, unnoticed by the paralyzed patient. We recently showed that internal strains and stresses in muscle and fat of individuals at anatomical sites susceptible to DTI can be evaluated by integrating Open-MRI scans with subject-specific finite element (FE) analyzes (Linder-Ganz et al., Journal of Biomechanics, 2007); however, sub-dermal soft tissue strains/stresses from paraplegics are still missing in literature. We hypothesize that the pathoanatomy of the buttocks in paraplegia increases the internal soft tissue loads under the IT, making these patients inherently susceptible to DTI. We hence compared the strain and stress peaks in the gluteus muscle and fat tissues under the IT of six healthy and six paraplegic patients, using the coupled MRI-FE method. Peak principal compression, principal tension, von Mises and shear strains in the gluteus were 1.2-, 3.1-, 1.4- and 1.4-fold higher in paraplegics than in healthy, respectively (p<0.02). Likewise, peak principal compression, principal tension, von Mises and shear stresses in the gluteus were 1.9-, 2.5-, 2.1- and 1.7-fold higher for the paraplegics (p<0.05). Peak gluteal compression and shear stresses decreased by as much as 70% when the paraplegic patients moved from a sitting to a lying posture, indicating on the effectiveness of recommending such patients to lie down after prolonged periods of sitting. This is the first attempt to compare internal soft tissue loads between paraplegic and healthy subjects, using an objective standardized bioengineering method of analysis. The findings support our hypothesis that internal tissue loads are significantly higher in paraplegics, and that postural changes significantly affect these loads. The method of analysis is useful for quantifying the effectiveness of various interventions to alleviate sub-dermal tissue loads at sites susceptible to pressure ulcers and DTI, including cushions, mattresses, recommendations for posture and postural changes, etc.

Assessment of mechanical conditions in sub-dermal tissues during sitting: a combined experimental-MRI and finite element approach.

A common but potentially severe malady afflicting permanent wheelchair users is pressure sores caused by elevated soft tissue strains and stresses over a critical prolonged period of time. Presently, there is paucity of information regarding deep soft tissue strains and stresses in the buttocks of humans during sitting. Strain and stress distributions in deep muscle and fat tissues were therefore calculated in six healthy subjects during sitting, in a double-donut Open-MR system, using a "reverse engineering" approach. Specifically, finite element (FE) models of the undeformed buttock were built for each subject using MR images taken at the coronal plane in a non-weight-bearing sitting posture. Using a second MR image taken from each subject during weight-bearing sitting we characterized the ischial tuberosity sagging toward the sitting surface in weight-bearing, and used these data as displacement boundary conditions for the FE models. These subject-specific FE analyses showed that maximal tissue strains and stresses occur in the gluteal muscles, not in fat or at the skin near the body-seat interface. Peak principal compressive strain and stress in the gluteus muscle were 74+/-7% and 32+/-9 kPa (mean+/-standard deviation), respectively. Peak principal compressive strain and stress in enveloping fat tissue were 46+/-7% and 18+/-4 kPa, respectively. Models were validated by comparing measured peak interface pressures under the ischial tuberosities (17+/-4 kPa) with those calculated by means of FE (18+/-3 kPa), for each subject. This is the first study to quantify sub-dermal tissue strain and stress distributions in sitting humans, in vivo. These data are essential for understanding the aetiology of pressure sores, particularly those that were recently termed "deep tissue injury" at the US National Pressure Ulcer Advisory Panel (NPUAP) 2005 Consensus Conference.

Coronary artery calcium measurement with multi-detector row CT and low radiation dose: comparison between 55 and 165 mAs.

PURPOSE: To prospectively compare the results of coronary artery calcium (CAC) measurements obtained with 55- and 165-mAs electrocardiographically gated multi-detector row computed tomography (CT). MATERIALS AND METHODS: Institutional clinical study review board approval and written informed consent were obtained. Fifty-one consecutive subjects (mean age, 59 years +/- 10) were scanned consecutively by using 165 and 55 mAs. For each examination, the number of lesions, total calcium score (TCS) calculated with Agatston algorithm (130-HU threshold), and calcium mass (in milligrams) were measured. Noise was measured by averaging 1 standard deviation of the CT attenuation values in five consecutive transverse sections of the ascending aorta. Paired t test and Pearson correlation were used to compare measurements between the examinations. RESULTS: By using 55 mAs, CAC was detected (TCS > 0) in all 33 subjects in whom CAC was initially detected with 165 mAs. The mean values of CAC measures with 165 and 55 mAs, respectively, were as follows: number of lesions, 6.2 +/- 9.6 and 6.1 +/- 9.4; TCS, 123 +/- 223 and 126 +/- 225; and calcium mass, 23.25 mg +/- 43 and 24.25 mg +/- 44 (P value was not significant for all parameters). Significant high correlation was found between the two methods for all measures (r > 0.90, P < .01). Similar results were obtained with analysis by coronary vessel. Image noise was 9.3 HU +/- 2.1 with 165 mAs and 14.7 HU +/- 3.9 with 55 mAs (P < .001), with a parallel decrease in the volume CT dose index from 12 to 4 mGy. CONCLUSION: Radiation dose can be reduced (eg, 55 mAs) for CAC detection and measurement at multi-detector row CT and provides results comparable to those obtained with 165 mAs.

MRI guidance of focused ultrasound therapy of uterine fibroids: early results.

OBJECTIVE: The purpose of this study was to explore our hypothesis that MRI-guided focused ultrasound therapy for the treatment of uterine fibroids will lead to a significant reduction in symptoms and improvement in quality of life. We describe focused ultrasound therapy applications and the method for monitoring the thermal energy deposited in the fibroids, including the MRI parameters required, in a prospective review of 108 treatments. MATERIALS AND METHODS: Patients presenting with symptomatic uterine fibroids who attained a minimal symptom severity score and who would otherwise have been offered a hysterectomy were recruited. Thermal lesions were created within target fibroids using an MRI-guided focused ultrasound therapy system. The developing lesion was monitored using real-time MR thermometry, which was used to assess treatment outcome in real time to change treatment parameters and achieve the desired outcome. Fibroid volume, fibroid symptoms, and quality-of-life scores were measured before treatment and 6 months after treatment. Adverse events were actively monitored and recorded. RESULTS: In this study, 79.3% of women who had been treated reported a significant improvement in their uterine fibroid symptoms on follow-up health-related quality-of-life questionnaires, which supports our hypothesis. The mean reduction in fibroid volume at 6 months was 13.5%, but nonenhancing volume (mean, 51 cm(3)) remained within the treated fibroid at 6 months. CONCLUSION: This early description of MRI-guided focused ultrasound therapy treatment of fibroids includes follow-up data and shows that, although the volume reduction is moderate, it correlates with treatment volume and the symptomatic response to this treatment is encouraging.

Accelerated progression of coronary calcification: four-year follow-up in patients with stable coronary artery disease.

PURPOSE: To prospectively assess the 4-year progression rate of coronary artery calcium (CAC) in patients with clinically stable coronary artery disease (CAD) with multi-detector row computed tomography (CT). MATERIALS AND METHODS: The study group consisted of 382 consecutive patients. All underwent baseline dual-sector spiral CT, and CT was repeated at 2 and 4 years later. Progression of CAC was assessed with measurement of the increase in total calcium score (TCS) and with repeated-measures analysis and multivariate linear regression models. Logistic regression model was used to predict incidence of new lesions. RESULTS: Eighty-seven percent (333 of 382) of the study group were men, with mean age of 65 years +/- 11, and 13% (49 of 382) were women, with mean age of 68 years +/- 11. The average TCS increased after 4 years by sixfold from baseline in the 1st quartile, and by four-, two- and 1.5-fold in the 2nd, 3rd, and 4th quartiles of baseline TCS (P <.01), respectively. Multiple linear regression analysis included age; sex; natural logarithm of baseline TCS; history of hypertension, diabetes mellitus, current smoking, hypercholesterolemia, and lipid-lowering therapy with cholesterol synthesis enzyme inhibitor (statin); and family history of premature CAD. Results demonstrated that natural logarithm of baseline TCS and history of current smoking were independent predictors of the 4th-year natural logarithm of TCS levels (R(2) = 0.85, P <.001). New lesions were diagnosed in 56 (15%) patients. History of statin therapy (odds ratio = 0.35; 95% confidence interval [CI]: 0.16, 0.77; P <.01), age with an increment of 5 years (odds ratio = 0.76; 95% CI: 0.64, 0.90; P =.01), and natural logarithm of baseline TCS (odds ratio = 0.73; 95% CI: 0.62, 0.86; P <.01) were independent predictors for new calcific lesions during 4 years. CONCLUSION: Accelerated progression of CAC during 4 years was found in clinically stable patients with CAD.

Coronary calcium by spiral computed tomography predicts cardiovascular events in high-risk hypertensive patients.

OBJECTIVE: The ability of coronary artery calcium (CAC) to predict coronary events has been shown in several studies. We aimed to investigate the hypothesis that CAC as assessed by dual slice spiral computed tomography (DSCT), is an independent risk factor for cardiovascular events in hypertensive patients. METHODS: We followed 446 participants of INSIGHT (International Nifedipine Study Intervention as Goal for Hypertension Therapy) calcification study, for the incidence of cardiovascular events as a function of CAC and other factors. All were hypertensive, without coronary artery disease (CAD), ages > 55 years and with at least one more major cardiovascular risk factor. All underwent a baseline DSCT and were followed for a mean period of 3.8 +/- 0.4 years. All events were documented while the scheduled visits and confirmed by the INSIGHT critical event committee. RESULTS: Follow-up was conducted on all participants. 294 patients (66%) had CAC at baseline. Forty-seven patients experienced a first cardiovascular event: acute myocardial infarction (MI), 16; sudden cardiac death, two; unstable angina resulting in revascularization, 14; stroke, 15. The incidence of first cardiovascular events was 3.7 times higher among those who had CAC at baseline than among those who had no CAC (14.5% (41 of 294) versus 3.9% (6 of 152)). Patients who experienced an event were more likely to be males, had had higher prevalence of peripheral vascular disease, longer duration of hypertension, and had higher levels of systolic blood pressure (SBP), glucose, creatinine and uric acid. Adjusting for these covariates, CAC (total coronary calcium score (TCS) > 0) independently predicted cardiovascular events with an odds ratio (OR) of 2.76 [95% confidence interval (CI) 1.09-6.99, P = 0.032]. CONCLUSION: The presence of CAC predicts cardiovascular events in high-risk asymptomatic hypertensive patients.

Coronary calcification compared in patients with acute versus in those with chronic coronary events by using dual-sector spiral CT.

PURPOSE: To compare underlying calcific atherosclerotic lesions in acute versus chronic coronary events in patients with hypertension by using dual-sector spiral computed tomography (CT). MATERIALS AND METHODS: Eight hundred eighty-four calcific lesions were analyzed in a cohort of 50 patients (39 men, 11 women; age range, 55-79 years; mean age, 66 years +/- 6 [SD]) with hypertension who sustained a coronary event during 3-year follow-up. All underwent dual-sector spiral CT within 12 months before the event. Twenty-nine patients had an acute event (acute group): acute myocardial infarction, 20; unstable angina pectoris, six; acute ischemia, two; sudden death, one. Twenty-one patients had chronic manifestations of obstructive coronary disease (chronic group): severe stable angina, five; angiographically identified disease, 12; disease requiring angioplasty, two; and disease requiring bypass surgery, two. To examine differences between the two study groups, the chi(2) or Fisher exact test was applied to categorical parameters and the two-sample t test or Wilcoxon rank sum test to quantitative parameters. RESULTS: High prevalence of coronary calcium (total coronary calcium score [TCS] >0) was observed in both groups: 93% (27 of 29) in the acute and 95% (20 of 21) in the chronic group. There were 518 lesions in the chronic and 366 in the acute group, with a median number of 35 and nine lesions per patient, respectively (P <.001). The median TCS was 906 for the chronic and 63 for the acute group (P <.01). CONCLUSION: A mild degree of calcification characterizes patients with acute coronary events, while diffuse high-attenuation calcific plaques are associated with chronic coronary events.