Quality of MR thermometry during palliative MR-guided high-intensity focused ultrasound (MR-HIFU) treatment of bone metastases.

BACKGROUND: Magnetic resonance (MR)-guided high-intensity focused ultrasound has emerged as a clinical option for palliative treatment of painful bone metastases, with MR thermometry (MRT) used for treatment monitoring. In this study, the general image quality of the MRT was assessed in terms of signal-to-noise ratio (SNR) and apparent temperature variation. Also, MRT artifacts were scored for their occurrence and hampering of the treatment monitoring. METHODS: Analyses were performed on 224 MRT datasets retrieved from 13 treatments. The SNR was measured per voxel over time in magnitude images, in the target lesion and surrounding muscle, and was averaged per treatment. The standard deviation over time of the measured temperature per voxel in MRT images, in the muscle outside the heated region, was defined as the apparent temperature variation and was averaged per treatment. The scored MRT artifacts originated from the following sources: respiratory and non-respiratory time-varying field inhomogeneities, arterial ghosting, and patient motion by muscle contraction and by gross body movement. Distinction was made between lesion type, location, and procedural sedation and analgesic (PSA). RESULTS: The average SNR was highest in and around osteolytic lesions (21 in lesions, 27 in surrounding muscle, n = 4) and lowest in the upper body (9 in lesions, 16 in surrounding muscle, n = 4). The average apparent temperature variation was lowest in osteolytic lesions (1.2°C, n = 4) and the highest in the upper body (1.7°C, n = 4). Respiratory time-varying field inhomogeneity MRT artifacts occurred in 85% of the datasets and hampered treatment monitoring in 81%. Non-respiratory time-varying field inhomogeneities and arterial ghosting MRT artifacts were most frequent (94% and 95%) but occurred only locally. Patient motion artifacts were highly variable and occurred less in treatments of osteolytic lesions and using propofol and esketamine as PSA. CONCLUSIONS: In this study, the general image quality of MRT was observed to be higher in osteolytic lesions and lower in the upper body. Respiratory time-varying field inhomogeneity was the most prominent MRT artifact. Patient motion occurrence varied between treatments and seemed to be related to lesion type and type of PSA. Clinicians should be aware of these observed characteristics when interpreting MRT images.

Detection of alterations in membrane metabolism during neoadjuvant chemotherapy in patients with breast cancer using phosphorus magnetic resonance spectroscopy at 7 Tesla.

Here we investigate the feasibility of tumor metabolism monitoring in T1c to T3 breast cancer during neoadjuvant chemotherapy by means of phosphorus ((31)P) magnetic resonance spectroscopy at 7 tesla (T). Five breast cancer patients were examined using a (31)P MRSI sequence, prior to-, halfway-, and after neoadjuvant chemotherapy. The (31)P MRSI data were analyzed on group and individual level and compared to a spectrum of a group of healthy volunteers. Ratios of phosphomonoesters (PME) to phosphodiesters (PDE) and phosphomonoesters to inorganic phosphate (Pi) were determined. Histopathologic assessment showed four partial responders and one complete responder to chemotherapy. The (31)P spectrum of the patient group was distinctly different from the (31)P spectrum of healthy volunteers and transformed its shape during the course of chemotherapy towards the shape of the spectrum of the healthy volunteers. Prior to chemotherapy the PME to PDE signal ratio and the PME to Pi signal ratio were high, and during the course of the chemotherapy these ratios normalized to the value of the healthy volunteers. Metabolite T 2 values in tumor tissue tended to be lower than those for healthy glandular tissue. Assessment of individual patients showed that four out of five had a significant drop of the PME to Pi ratio by a factor of 2 or more. On average, the pH of the tumor, calculated from chemical shift variation of Pi, was 0.19 units lower before chemotherapy. We have demonstrated that the sensitivity of (31)P MRSI in breast cancer at 7 T is sufficient to detect alterations in membrane metabolism during neoadjuvant chemotherapy, which may be used for early assessment of treatment efficacy.

Magnetic resonance imaging in breast cancer: A literature review and future perspectives.

Early detection and diagnosis of breast cancer are essential for successful treatment. Currently mammography and ultrasound are the basic imaging techniques for the detection and localization of breast tumors. The low sensitivity and specificity of these imaging tools resulted in a demand for new imaging modalities and breast magnetic resonance imaging (MRI) has become increasingly important in the detection and delineation of breast cancer in daily practice. However, the clinical benefits of the use of pre-operative MRI in women with newly diagnosed breast cancer is still a matter of debate. The main additional diagnostic value of MRI relies on specific situations such as detecting multifocal, multicentric or contralateral disease unrecognized on conventional assessment (particularly in patients diagnosed with invasive lobular carcinoma), assessing the response to neoadjuvant chemotherapy, detection of cancer in dense breast tissue, recognition of an occult primary breast cancer in patients presenting with cancer metastasis in axillary lymph nodes, among others. Nevertheless, the development of new MRI technologies such as diffusion-weighted imaging, proton spectroscopy and higher field strength 7.0 T imaging offer a new perspective in providing additional information in breast abnormalities. We conducted an expert literature review on the value of breast MRI in diagnosing and staging breast cancer, as well as the future potentials of new MRI technologies.

Invasive ductolobular carcinoma of the breast: spectrum of mammographic, ultrasound and magnetic resonance imaging findings correlated with proportion of the lobular component.

PURPOSE: The aim of this study was to describe the imaging features of patients with invasive ductolobular carcinoma of the breast in comparison with the proportion of the lobular component. MATERIALS AND METHODS: We retrospectively reviewed mammographic, sonographic and MRI records of 113 patients with proven ductolobular carcinoma diagnosed between January 2008 and October 2012 according to the BI-RADS ® lexicon, and correlated these to the proportion of the lobular component. RESULTS: At mammography the most common finding (62.9%) for invasive ductolobular carcinoma was an irregular, spiculated and isodense mass. On ultrasound an irregular and hypoechoic mass, with spiculated margins and posterior acoustic shadowing was observed in 46.8% of cases. Isolated mass and mass associated with non-mass like enhancement (NMLE) were the most common findings by MRI (89.4%). Washout pattern in delayed phase was seen in 61.2% and plateau curve was more frequently observed in patients with larger lobular component. Additional malignant findings (multifocality, multicentricity and contralateral disease) did not correlate significantly with the proportion of the lobular component. CONCLUSION: Invasive ductolobular carcinoma mainly presents as an irregular, spiculated mass, isodense on mammography and hypoechoic with posterior acoustic shadowing. On MRI it is usually seen as an isolated mass or as a dominant mass surrounded by smaller masses or NMLE. Washout is the most ordinary kinetic pattern of these tumors. In general, the imaging characteristics did not vary significantly with the proportion of the lobular component.

Localization of nonpalpable breast lesions.

The introduction of mammography screening and improvements in diagnostic tools resulted in a major increase of breast cancers detectable as small, nonpalpable lesions suitable for breast-conserving treatment. Accurate preoperative localization of these cancers is a necessity. Several methods are available for localization, of which wire-guided localization is considered the current gold standard. Promising techniques are radio-guided occult lesion localization, radioactive seed localization and ultrasound-guided surgery. In this article, an overview of the various localization techniques is provided, describing advantages, shortcomings and effectiveness.