Osseous-Tissue Tumor Reporting and Data System With Diffusion-Weighted Imaging of Bone Tumors-An Interreader Analysis and Whether It Adds Incremental Value on Tumor Grading Over Conventional Magnetic Resonance Imaging.

OBJECTIVE: The aim of the study is to determine whether the use of diffusion-weighted imaging (DWI) provides incremental increase in performance in the osseous-tissue tumor reporting and data system (OT-RADS) with the hypothesis that use of DWI improves interreader agreement and diagnostic accuracy. METHODS: In this multireader cross-sectional validation study, multiple musculoskeletal radiologists reviewed osseous tumors with DW images and apparent diffusion coefficient maps. Four blinded readers categorized each lesion using the OT-RADS categorizations. Intraclass correlation (ICC) and Conger κ were used. Diagnostic performance measures including area under the receiver operating curve were reported. These measures were then compared with the previously published work that validated OT-RADS but did not include incremental value assessment of DWI. RESULTS: One hundred thirty-three osseous tumors of the upper and lower extremities (76 benign, 57 malignant) were tested. Interreader agreement for OT-RADS with DWI (ICC = 0.69) was slightly lower (not statistically different) from the previously published work that did not incorporate DWI (ICC = 0.78, P > 0.05). The mean sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating curve including DWI of the 4 readers were 0.80, 0.95, 0.96, 0.79, and 0.91, respectively. In the previously published work without DWI, the mean values of the readers were 0.96, 0.79, 0.78, 0.96, and 0.94, respectively. CONCLUSIONS: The addition of DWI to the OT-RADS system does not allow significantly improved area under the curve diagnostic performance measure. Conventional magnetic resonance imaging can be prudently used for OT-RADS for reliable and accurate characterization of bone tumors.

Osseous Tumor Reporting and Data System-Multireader Validation Study.

OBJECTIVE: To develop and validate an Osseous Tumor Reporting and Data System (OT-RADS) with the hypothesis that the proposed guideline is reliable and assists in separating benign from malignant osseous tumors with a good area under the curve, and that could assist further patient management. METHODS: In this multireader cross-sectional validation study, an agreement was reached for OT-RADS categories based on previously described magnetic resonance imaging features and consensus of expert musculoskeletal radiologists. World Health Organization classification was used, and a wide spectrum of benign and malignant osseous tumors was evaluated. Magnetic resonance imaging categories were as follows: OT-RADS 0-incomplete imaging; OT-RADS I-negative; OT-RADS II-definitely benign; OT-RADS III-probably benign; OT-RADS IV-suspicious for malignancy or indeterminate; OT-RADS V-highly suggestive of malignancy; and OT-RADS VI-known biopsy-proven malignancy or recurrent malignancy in the tumor bed. Four blinded readers categorized each tumor according to OT-RADS classification. Intraclass correlation (ICC) and Conger κ were used. Diagnostic performance measures including area under the receiver operating curve were reported. Osseous Tumor Reporting and Data System was dichotomized as benign (I-III) and malignant (IV and V) for calculating sensitivity and specificity. RESULTS: Interreader agreement for OT-RADS (ICC = 0.78) and binary distinction of benign versus malignant (κ = 0.67) were good to excellent, while agreement for individual tumor feature characteristics were poor to fair (ICC = 0.25-0.36; κ = 0.16-0.39). The sensitivities, specificities, and area under the receiver operating curve of the readers ranged from 0.93-1.0, 0.71-0.86, and 0.92-0.97, respectively. CONCLUSIONS: Osseous Tumor Reporting and Data System lexicon is reliable and helps stratify tumors into benign and malignant categories. It can be practically used by radiologists to guide patient management, improve multidisciplinary communications, and potentially impact outcomes.

MRI, Clinical Examination, and Mammography for Preoperative Assessment of Residual Disease and Pathologic Complete Response After Neoadjuvant Chemotherapy for Breast Cancer: ACRIN 6657 Trial.

OBJECTIVE: The objective of our study was to determine the accuracy of preoperative measurements for detecting pathologic complete response (CR) and assessing residual disease after neoadjuvant chemotherapy (NACT) in patients with locally advanced breast cancer. SUBJECTS AND METHODS: The American College of Radiology Imaging Network 6657 Trial prospectively enrolled women with ≥ 3 cm invasive breast cancer receiving NACT. Preoperative measurements of residual disease included longest diameter by mammography, MRI, and clinical examination and functional volume on MRI. The accuracy of preoperative measurements for detecting pathologic CR and the association with final pathology size were assessed for all lesions, separately for single masses and nonmass enhancements (NMEs), multiple masses, and lesions without ductal carcinoma in situ (DCIS). RESULTS: In the 138 women with all four preoperative measures, longest diameter by MRI showed the highest accuracy for detecting pathologic CR for all lesions and NME (AUC = 0.76 and 0.84, respectively). There was little difference across preoperative measurements in the accuracy of detecting pathologic CR for single masses (AUC = 0.69-0.72). Longest diameter by MRI and longest diameter by clinical examination showed moderate ability for detecting pathologic CR for multiple masses (AUC = 0.78 and 0.74), and longest diameter by MRI and longest diameter by mammography showed moderate ability for detecting pathologic CR for tumors without DCIS (AUC = 0.74 and 0.71). In subjects with residual disease, longest diameter by MRI exhibited the strongest association with pathology size for all lesions and single masses (r = 0.33 and 0.47). Associations between preoperative measures and pathology results were not significantly influenced by tumor subtype or mammographic density. CONCLUSION: Our results indicate that measurement of longest diameter by MRI is more accurate than by mammography and clinical examination for preoperative assessment of tumor residua after NACT and may improve surgical planning.

MR spectroscopy of breast cancer for assessing early treatment response: Results from the ACRIN 6657 MRS trial.

PURPOSE: To estimate the accuracy of predicting response to neoadjuvant chemotherapy (NACT) in patients with locally advanced breast cancer using MR spectroscopy (MRS) measurements made very early in treatment. MATERIALS AND METHODS: This prospective Health Insurance Portability and Accountability Act (HIPAA)-compliant protocol was approved by the American College of Radiology and local-site institutional review boards. One hundred nineteen women with invasive breast cancer of ≥3 cm undergoing NACT were enrolled between September 2007 and April 2010. MRS measurements of the concentration of choline-containing compounds ([tCho]) were performed before the first chemotherapy regimen (time point 1, TP1) and 20-96 h after the first cycle of treatment (TP2). The change in [tCho] was assessed for its ability to predict pathologic complete response (pCR) and radiologic response using the area under the receiver operating characteristic curve (AUC) and logistic regression models. RESULTS: Of the 119 subjects enrolled, only 29 cases (24%) with eight pCRs provided usable data for the primary analysis. Technical challenges in acquiring quantitative MRS data in a multi-site trial setting limited the capture of usable data. In this limited data set, the decrease in tCho from TP1 to TP2 had poor ability to predict either pCR (AUC = 0.53, 95% confidence interval [CI]: 0.27-0.79) or radiologic response (AUC = 0.51, 95% CI: 0.27-0.75). CONCLUSION: The technical difficulty of acquiring quantitative MRS data in a multi-site clinical trial setting led to a low yield of analyzable data, which was insufficient to accurately measure the ability of early MRS measurements to predict response to NACT. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:290-302.

Neoadjuvant Chemotherapy for Breast Cancer: Functional Tumor Volume by MR Imaging Predicts Recurrence-free Survival-Results from the ACRIN 6657/CALGB 150007 I-SPY 1 TRIAL.

PURPOSE: To evaluate volumetric magnetic resonance (MR) imaging for predicting recurrence-free survival (RFS) after neoadjuvant chemotherapy (NACT) of breast cancer and to consider its predictive performance relative to pathologic complete response (PCR). MATERIALS AND METHODS: This HIPAA-compliant prospective multicenter study was approved by institutional review boards with written informed consent. Women with breast tumors 3 cm or larger scheduled for NACT underwent dynamic contrast-enhanced MR imaging before treatment (examination 1), after one cycle (examination 2), midtherapy (examination 3), and before surgery (examination 4). Functional tumor volume (FTV), computed from MR images by using enhancement thresholds, and change from baseline (ΔFTV) were measured after one cycle and before surgery. Association of RFS with FTV was assessed by Cox regression and compared with association of RFS with PCR and residual cancer burden (RCB), while controlling for age, race, and hormone receptor (HR)/ human epidermal growth factor receptor type 2 (HER2) status. Predictive performance of models was evaluated by C statistics. RESULTS: Female patients (n = 162) with FTV and RFS were included. At univariate analysis, FTV2, FTV4, and ΔFTV4 had significant association with RFS, as did HR/HER2 status and RCB class. PCR approached significance at univariate analysis and was not significant at multivariate analysis. At univariate analysis, FTV2 and RCB class had the strongest predictive performance (C statistic = 0.67; 95% confidence interval [CI]: 0.58, 0.76), greater than for FTV4 (0.64; 95% CI: 0.53, 0.74) and PCR (0.57; 95% CI: 0.39, 0.74). At multivariate analysis, a model with FTV2, ΔFTV2, RCB class, HR/HER2 status, age, and race had the highest C statistic (0.72; 95% CI: 0.60, 0.84). CONCLUSION: Breast tumor FTV measured by MR imaging is a strong predictor of RFS, even in the presence of PCR and RCB class. Models combining MR imaging, histopathology, and breast cancer subtype demonstrated the strongest predictive performance in this study.

Blood oxygenation level-dependent (BOLD) contrast magnetic resonance imaging (MRI) for prediction of breast cancer chemotherapy response: a pilot study.

PURPOSE: To determine whether a simple noninvasive method of assessing tumor oxygenation is feasible in the clinical setting and can provide useful, potentially predictive information. Tumor microcirculation and oxygenation play critical roles in tumor growth and responsiveness to cytotoxic treatment and may provide prognostic indicators for cancer therapy. Deoxyhemoglobin is paramagnetic and can serve as an endogenous contrast agent causing signal loss in echo planar magnetic resonance imaging (MRI) (blood oxygenation level-dependent [BOLD]-MRI). We used BOLD-MRI to provide early evaluation of response to neoadjuvant chemotherapy in patients with locally advanced breast cancer. MATERIALS AND METHODS: MRI was performed on 11 patients with biopsy-proven malignancy. MRI exams were scheduled before, during, and after chemotherapy. The BOLD study applied a 6-minute oxygen breathing challenge. RESULTS: Seven patients successfully completed the exams. Before chemotherapy, BOLD contrast enhancement was observed in all tumors, but the patients, who ultimately had complete pathological response, exhibited a significantly higher BOLD response to oxygen breathing. CONCLUSION: We have successfully implemented an oxygen-breathing challenge BOLD contrast technique as part of the standard breast MRI exam in patients with locally advanced breast cancer. The preliminary observation that a large BOLD response correlated with better treatment response suggests a predictive capability for BOLD MRI.

Simultaneous measurement of tissue oxygen level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) effects in abdominal tissue oxygenation level studies.

PURPOSE: To assess oxygenation in abdominal organs with magnetic resonance imaging (MRI), a novel approach is presented to simultaneously measure both T1 - and T2*-maps serially during a single dynamic MRI scan in response to an oxygen challenge. MATERIALS AND METHODS: The proposed acquisition scheme consists of a multishot multiecho gradient echo planar imaging sequence (ms-GEPI) interleaved with a multishot inversion recovery echo planar imaging (ms-IR-EPI) sequence. Respiratory motion compensation was accomplished with standard belt triggering and by acquiring all image data at the same phase of expiration. This respiratory-triggered, free-breathing, interleaved tissue oxygenation level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) acquisition technique was validated on phantoms and seven healthy volunteers in response to an oxygen challenge. RESULTS: Measurements of relaxation times both in vitro and in vivo were in good agreement with those obtained using conventional pulse sequences and reported in the literature. The interleaved sequence was able to measure oxygen-induced relaxation time changes in human abdominal organs. CONCLUSION: The free-breathing respiratory-triggered interleaved T1 and T2* sequence successfully provided relaxation time maps of abdominal organs in a dynamic scan without the need for image registration. The simultaneous monitoring of tissue and blood oxygenation improves time efficiency and should enhance studies comparing dynamic T1 and T2* data within the abdomen.

Diffusion weighted imaging of extremity bone tumors-inter-reader analysis and incremental value over conventional MR imaging.

OBJECTIVE: To determine whether the addition of diffusion-weighted imaging (DWI) to conventional MRI improves diagnostic accuracy of bone tumor characterization with the hypothesis that the DWI has incremental value in the diagnosis of osseous tumors. METHODS: In this multireader cross-sectional validation study, four musculoskeletal radiologists evaluated osseous tumors blinded to final diagnosis in two rounds-first without DWI or apparent diffusion coefficient (ADC) maps, then months later with these available. Each reader recorded a binary result as to whether the lesion is benign or malignant. Intraclass correlation (ICC) and Conger's κ were used. Diagnostic performance measures including area under the receiver operating curve (AUC) were reported. RESULTS: 133 osseous tumors of the extremities (76 benign, 57 malignant) were tested. Blinded to DWI, average reader sensitivity, specificity, positive-predictive value, and negative-predictive value were 0.83, 0.92, 0.94, and 0.82, respectively. With DWI, the values were 0.85, 0.92, 0.94, and 0.83, respectively. Interreader agreement was good for both rounds (0.67 and 0.71, respectively, p-value > 0.05). Average reader confidence was 4.1 and 4.4, respectively (p-value < 0.001). ADC values and DWI/ADC ratios showed significant differences between benign and malignant tumors. CONCLUSION: DWI and ADC show statistically significantly different values of benign from malignant osseous tumors and mildly increased radiologist confidence with similar interreader reliability. However, given similar diagnostic accuracy, conventional MR imaging is adequate for bone tumor characterization and incremental value of DWI is limited. ADVANCES IN KNOWLEDGE: This paper is the first of its kind to report the use of DWI/ADC ratio for the diagnosis of bone tumors.

Locally advanced breast cancer: MR imaging for prediction of response to neoadjuvant chemotherapy--results from ACRIN 6657/I-SPY TRIAL.

PURPOSE: To compare magnetic resonance (MR) imaging findings and clinical assessment for prediction of pathologic response to neoadjuvant chemotherapy (NACT) in patients with stage II or III breast cancer. MATERIALS AND METHODS: The HIPAA-compliant protocol and the informed consent process were approved by the American College of Radiology Institutional Review Board and local-site institutional review boards. Women with invasive breast cancer of 3 cm or greater undergoing NACT with an anthracycline-based regimen, with or without a taxane, were enrolled between May 2002 and March 2006. MR imaging was performed before NACT (first examination), after one cycle of anthracyline-based treatment (second examination), between the anthracycline-based regimen and taxane (third examination), and after all chemotherapy and prior to surgery (fourth examination). MR imaging assessment included measurements of tumor longest diameter and volume and peak signal enhancement ratio. Clinical size was also recorded at each time point. Change in clinical and MR imaging predictor variables were compared for the ability to predict pathologic complete response (pCR) and residual cancer burden (RCB). Univariate and multivariate random-effects logistic regression models were used to characterize the ability of tumor response measurements to predict pathologic outcome, with area under the receiver operating characteristic curve (AUC) used as a summary statistic. RESULTS: Data in 216 women (age range, 26-68 years) with two or more imaging time points were analyzed. For prediction of both pCR and RCB, MR imaging size measurements were superior to clinical examination at all time points, with tumor volume change showing the greatest relative benefit at the second MR imaging examination. AUC differences between MR imaging volume and clinical size predictors at the early, mid-, and posttreatment time points, respectively, were 0.14, 0.09, and 0.02 for prediction of pCR and 0.09, 0.07, and 0.05 for prediction of RCB. In multivariate analysis, the AUC for predicting pCR at the second imaging examination increased from 0.70 for volume alone to 0.73 when all four predictor variables were used. Additional predictive value was gained with adjustments for age and race. CONCLUSION: MR imaging findings are a stronger predictor of pathologic response to NACT than clinical assessment, with the greatest advantage observed with the use of volumetric measurement of tumor response early in treatment.

Oxygenation in cervical cancer and normal uterine cervix assessed using blood oxygenation level-dependent (BOLD) MRI at 3T.

Hypoxia is reported to be a biomarker for poor prognosis in cervical cancer. However, a practical noninvasive method is needed for the routine clinical evaluation of tumor hypoxia. This study examined the potential use of blood oxygenation level-dependent (BOLD) contrast MRI as a noninvasive technique to assess tumor vascular oxygenation at 3T. Following Institutional Review Board-approved informed consent and in compliance with the Health Insurance Portability and Accountability Act, successful results were achieved in nine patients with locally advanced cervical cancer [International Federation of Gynecology and Obstetrics (FIGO) stage IIA to IVA] and three normal volunteers. In the first four patients, dynamic T2*-weighted MRI was performed in the transaxial plane using a multi-shot echo planar imaging sequence whilst patients breathed room air followed by oxygen (15 dm³/min). Later, a multi-echo gradient echo examination was added to provide quantitative R2* measurements. The baseline T2*-weighted signal intensity was quite stable, but increased to various extents in tumors on initiation of oxygen breathing. The signal in normal uterus increased significantly, whereas that in the iliacus muscle did not change. R2* responded significantly in healthy uterus, cervix and eight cervical tumors. This preliminary study demonstrates that BOLD MRI of cervical cancer at 3T is feasible. However, more patients must be evaluated and followed clinically before any prognostic value can be determined.

Phase I dose-escalation study of stereotactic body radiotherapy in patients with hepatic metastases.

PURPOSE: To identify a tolerable and effective dose for 5-fraction stereotactic body radiotherapy for hepatic metastases. METHODS: Patients were enrolled onto three dose-escalation cohorts: 30 Gy in 3 fractions, 50 Gy in 5 fractions, and 60 Gy in 5 fractions. Eligible patients had one to five hepatic metastases, ability to spare a critical hepatic volume (volume receiving <21 Gy) of 700 ml, adequate baseline hepatic function, no concurrent antineoplastic therapy, and a Karnofsky performance score of ≥60. Dose-limiting toxicity included treatment-related grade 3 toxicity in the gastrointestinal, hepatobiliary/pancreas, and metabolic/laboratory categories. Any grade 4 or 5 event attributable to therapy was defined as a dose-limiting toxicity. Local control (LC) and complete plus partial response rates were assessed. RESULTS: Twenty-seven patients, 9 in each cohort, with 37 lesions were enrolled and treated: 17 men and 11 women; median age 62 (range 48-86) years; most common site of primary disease, colorectal (44.4%). Median follow-up was 20 (range 4-53) months. There was no grade 4 or 5 toxicity or treatment-related grade 3 toxicity. Actuarial 24-month LC rates for the 30-, 50-, and 60-Gy cohorts were 56%, 89%, and 100%, respectively. There was a statistically significant difference for LC between the 60- and 30-Gy cohorts (P = 0.009) but not between the 60- and 50-Gy cohorts (P = 0.56) or the 50- and 30-Gy cohorts (P = 0.091). The maximum tolerated dose was not reached. CONCLUSIONS: A dose of 60 Gy in 5 fractions can be safely delivered to selected patients with hepatic metastases as long as the critical liver volume is respected. A dose of 60 Gy in 5 fractions yields an excellent level of LC.

Morphologic blooming in breast MRI as a characterization of margin for discriminating benign from malignant lesions.

RATIONALE AND OBJECTIVES: Develop a fully automated, objective method for evaluating morphology on breast magnetic resonance (MR) images and evaluate effectiveness of the new morphologic method for detecting breast cancers. MATERIALS AND METHODS: We present a new automated method (morphologic blooming) for identifying and classifying breast lesions on MR that measures margin sharpness, a characteristic related to blooming, defined as rapid enhancement, with a border that is initially sharp but becomes unsharp after 7 minutes. Independent training sets (98 biopsy-proven lesions) and testing sets (179 breasts, 127 patients, acquired at five institutions) were used. Morphologic blooming was evaluated as a stand-alone feature and as an adjunct to kinetics using free-response receiver operating characteristic and sensitivity analysis. Dependence of false-positive (FP) rates on acquisition times and pathologies of contralateral breasts were evaluated. RESULTS: Sensitivity of morphologic blooming was 80% with 2.46 FP per noncancerous breast: FPs did not vary significantly by acquisition times. FPs varied significantly by pathologies of contralateral breasts (cancerous contralateral: 4.29 FP/breast; noncancerous contralateral: 0.48 FP/breast; P < .0001). Evaluation of 45 cancers showed suspicious morphologies on 10/15 (67%) cancers with benign-like kinetics and suspicious kinetics on 5/10 (50%) cancers with benign-like morphologies. CONCLUSION: We present a new, fully automated method of identifying and classifying margin sharpness of breast lesions on MR that can be used to direct radiologists' attention to lesions with suspicious morphologies. Morphologic blooming may have important utility for assisting radiologists in identifying cancers with benign-like kinetics and discriminating normal tissues that exhibit cancer-like enhancement curves and for improving the performance of computer-aided detection systems.

Regional body fat distribution in HIV-infected patients with lipodystrophy.

BACKGROUND: Objective criteria for the assessment of patients with lipodystrophy syndrome in human immunodeficiency virus infection (LDHIV) have not emerged. METHODS: We compared regional body fat changes in 13 men with severe LDHIV on protease inhibitor-inclusive antiretroviral therapy with 13 control HIV-infected men using anthropometry, dual-energy X-ray absorptiometry (DEXA), and whole-body magnetic resonance imaging (MRI). RESULTS: LDHIV patients, compared with control subjects, had thinner gluteal, suprailiac, and triceps skinfolds (p < .01) and increased waist circumference (98 +/- 5 cm vs 86 +/- 9 cm, respectively; p = .0008). DEXA studies revealed reduced lower extremity fat (12 +/- 5% vs 22 +/- 9%; p = .0006), increased head and neck fat (18 +/- 3% vs 16 +/- 1%; p = .01), and increased proportion of total body fat in the trunk (65 +/- 7% vs 53 +/- 8%; p = .0005). MRI analysis revealed reduced thigh fat (12 +/- 5% vs 22 +/- 12%; p = .01), increased dorsocervical fat depth (47 +/- 24 mm vs 19 +/- 7 mm; p = .0009), and nearly significant increase in intra-abdominal fat (218 +/- 90 cm2 vs 157 +/- 70 cm2; p = .057). Interestingly, control subjects showed a positive relationship between intra-abdominal and dorsocervical fat (r= .57, p = .04), but the LDHIV patients showed a negative relationship (r= -.55, p = .05), suggesting a novel split phenotype among LDHIV patients of either dorsocervical or intra-abdominal fat accumulation. CONCLUSIONS: We conclude that MRI provides the best tools for definition of LDHIV syndrome and reveals variable phenotypes among LDHIV patients.

The effect of screening for deep vein thrombosis on the prevalence of pulmonary embolism in patients with fractures of the pelvis or acetabulum: a review of 973 patients.

OBJECTIVES: In patients with pelvic or acetabular fractures, to compare the prevalence of pulmonary embolism in a time period without screening for deep vein thrombosis to that seen when a screening protocol was in place. DESIGN: Retrospective. SETTING: County hospital. PATIENTS: All patients with closed fractures of the pelvis or acetabulum treated during the study periods. INTERVENTION: Prophylaxis for deep vein thrombosis was the same for both groups. From November 1, 1997 though November 31, 1999, a screening protocol for deep vein thrombosis was employed using ultrasound and magnetic resonance venography. From January 1, 2000 through December 1, 2001, no screening was used. MAIN OUTCOME MEASUREMENT: Pulmonary emboli were recorded. RESULTS: The 1997 to 1999 time period included 486 patients with fractures of the pelvis or acetabulum; the 2000 to 2001 time period included 487. In the period when a screening protocol was in place, 10 patients (2%) were diagnosed with pulmonary embolism by pulmonary arteriogram, autopsy, or ventilation perfusion scan. All but 2 who were diagnosed with pulmonary embolism had undergone screening for deep vein thrombosis, and none of the screening tests were positive. In the 2000 to 2001 time period, when no screening for deep vein thrombosis was done, 7 patients (1.4%) were diagnosed with pulmonary embolism, by pulmonary arteriogram, autopsy, spiral computed tomography scan, or high clinical suspicion. There was no significant difference between the prevalence of pulmonary embolism seen in 1997 to 1999 and that seen in 2000 to 2001 (P = 0.48). CONCLUSION: Discontinuation of screening for the diagnosis of deep vein thrombosis did not change the rate of pulmonary embolism.

Interventional MR imaging with an endospinal imaging coil: preliminary results with anatomic imaging of the canine and cadaver spinal cord.

Percutaneous intraspinal navigation (PIN) is a new minimally invasive approach to the subarachnoid space. Using conventional radiographic fluoroscopy, entrance is gained to the lumbar subarachnoid space, allowing navigation throughout the spinal canal. Using an antenna/guidewire introduced via PIN, we performed endospinal MR imaging of the thoracic spinal cord in a cadaver and canine subject. Comparison images were obtained with an optimal surface coil. PIN allows endospinal MR imaging of the spinal cord, providing significant signal-to-noise ratio gains over conventional imaging.

MR-guided catheter navigation of the intracranial subarachnoid space.

Percutaneous intraspinal navigation (PIN) is a new minimally invasive approach to the CNS. The authors studied the utility of MR-guided intracranial navigation following access to the subarachnoid compartment via PIN. The passive tracking technique was employed to visualize devices during intracranial navigation. Under steady-state free precession (SSFP) MR-guidance a microcatheter-microguidewire was successfully navigated to multiple brain foci in two cadavers. SSFP MR fluoroscopy possesses adequate contrast and temporal resolution to allow MR-guided intracranial navigation.

Magnetic resonance imaging of the breast prior to biopsy.

CONTEXT: Breast magnetic resonance imaging (MRI) has been shown to have high sensitivity for cancer detection and is increasingly used following mammography to evaluate suspicious breast lesions. OBJECTIVE: To determine the accuracy of breast MRI in conjunction with mammography for the detection of breast cancer in patients with suspicious mammographic or clinical findings. DESIGN, SETTING, AND PATIENTS: Prospective multicenter investigation of the International Breast MR Consortium conducted at 14 university hospitals in North America and Europe from June 2, 1998, through October 31, 2001, of 821 patients referred for breast biopsy for American College of Radiology category 4 or 5 mammographic assessment or suspicious clinical or ultrasound finding. INTERVENTIONS: MRI examinations performed prior to breast biopsy; MRI results were interpreted at each site, which were blinded to pathological results. MAIN OUTCOME MEASURES: Area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of breast MRI. RESULTS: Among the 821 patients, there were 404 malignant index lesions, of which 63 were ductal carcinoma in situ (DCIS) and 341 were invasive carcinoma. Of the 417 nonmalignant index lesions, 366 were benign, 47 showed atypical histology, and 4 were lobular carcinoma in situ. The AUC pooled over all institutions was 0.88 (95% confidence interval [CI], 0.86-0.91). MRI correctly detected cancer in 356 of 404 cancer cases (DCIS or invasive cancer), resulting in a sensitivity of 88.1% (95% CI, 84.6%-91.1%), and correctly identified as negative for cancer 281 of 417 cases without cancer, resulting in a specificity of 67.7% (95% CI, 62.7%-71.9%). MRI performance was not significantly affected by mammographic breast density, tumor histology, or menopausal status. The positive predictive values for 356 of 492 patients was 72.4% (95% CI, 68.2%-76.3%) and of mammography for 367 of 695 patients was 52.8% (95% CI, 49.0%-56.6%) (P<.005). Dynamic MRI did not improve the AUC compared with 3-dimensional MRI alone, but the specificity of a washout pattern for 123 of 136 patients without cancer was 90.4% (95% CI, 84%-95%). CONCLUSIONS: Breast MRI has high sensitivity but only moderate specificity independent of breast density, tumor type, and menopausal status. Although the positive predictive value of MRI is greater than mammography, MRI does not obviate the need for subsequent tissue sampling in this setting.

Increased skeletal muscle volume in women with familial partial lipodystrophy, Dunnigan variety.

INTRODUCTION: Familial partial lipodystrophy, Dunnigan variety (FPLD), an autosomal dominant disorder caused by LMNA mutations, is characterized by fat loss from the extremities. However, it is unclear whether these patients appear muscular because of a lack of subcutaneous fat or have an actual increase in muscle mass. Therefore, we compared muscle mass and volume of selected muscles in women with FPLD and control subjects using dual-emission x-ray absorptiometry (DXA) and magnetic resonance imaging (MRI). METHODS: Whole-body axial MRI and DXA scans were obtained on 39 women, aged 18 to 65 years, with FPLD and 17 healthy women matched for body mass index and age (group 1). Volumes of muscles in both the thighs, calves, and psoas were calculated from MRI scans and muscle mass in extremities were calculated from DXA. In addition, abdominal MRI and DXA scans were analyzed from 129 healthy, frequency-matched women (group 2). Comparisons between women with FPLD and control subjects were made using ANOVA, adjusting for height, body mass index, and age. RESULTS: Patients with FPLD, compared with control subjects had significantly greater volumes of the thigh muscles, (6358 ± 1491 vs 5198 ± 716 mL, P = .002), calf muscles (3133 ± 713 vs 2397 ± 335 mL; P < .001), and psoas muscles (210 ± 51 vs 175 ± 34 [group 1] and 165 ± 38 mL [group 2], P < .001). Patients with FPLD also had significantly increased arm and leg muscle masses when measured by DXA (P < .001). Insulin sensitivity, assessed by insulin tolerance tests, was negatively correlated to the calf muscle volume. CONCLUSIONS: Female patients with FPLD have increased skeletal muscle volume and mass compared with those of normal women.

Automated method for accurate abdominal fat quantification on water-saturated magnetic resonance images.

PURPOSE: To introduce and evaluate the performance of an automated fat quantification method for water-saturated magnetic resonance images. MATERIALS AND METHODS: A fat distribution model is proposed for fat quantification on water saturated magnetic resonance images. Fat from both full- and partial-volume voxels are accounted for in this model based on image intensity histogram analysis. An automated threshold method is therefore proposed to accurately quantify total fat. This method is compared to a traditional full-volume-fat-only method in phantom and human studies. In the phantom study, fat quantification was performed on MR images obtained from a human abdomen oil phantom and was compared with the true oil volumes. In the human study, results of the two fat quantification methods of six subjects were compared on abdominal images with different spatial resolutions. RESULTS: In the phantom study, the proposed method provided significantly more accurate estimations of true oil volumes compared to the reference method (P < 0.0001). In human studies, fat quantification using the proposed method gave much more consistent results on images with different spatial resolutions, and on regions with different degrees of partial volume averaging. CONCLUSION: The proposed automated method is simple, rapid, and accurate for fat quantification on water-saturated MR images.