Fast Spoiled Gradient-echo Images Research Articles

Deep Learning Reconstruction to Improve the Quality of MR Imaging: Evaluating the Best Sequence for T-category Assessment in Non-small Cell Lung Cancer Patients.

Deep learning reconstruction (DLR) has been recommended as useful for improving image quality. Moreover, compressed sensing (CS) or DLR has been proposed as useful for improving temporal resolution and image quality on MR sequences in different body fields. However, there have been no reports regarding the utility of DLR for image quality and T-factor assessment improvements on T2-weighted imaging (T2WI), short inversion time (TI) inversion recovery (STIR) imaging, and unenhanced- and contrast-enhanced (CE) 3D fast spoiled gradient echo (GRE) imaging with and without CS in comparison with thin-section multidetector-row CT (MDCT) for non-small cell lung cancer (NSCLC) patients. The purpose of this study was to determine the utility of DLR for improving image quality and the appropriate sequence for T-category assessment for NSCLC patients. As subjects for this study, 213 pathologically diagnosed NSCLC patients who underwent thin-section MDCT and MR imaging as well as T-factor diagnosis were retrospectively enrolled. SNR of each tumor was calculated and compared by paired t-test for each sequence with and without DLR. T-factor for each patient was assessed with thin-section MDCT and all MR sequences, and the accuracy for T-factor diagnosis was compared among all sequences and thin-section CT by means of McNemar's test. SNRs of T2WI, STIR imaging, unenhanced thin-section Quick 3D imaging, and CE-thin-section Quick 3D imaging with DLR were significantly higher than SNRs of those without DLR (P < 0.05). Diagnostic accuracy of STIR imaging and CE-thick- or thin-section Quick 3D imaging was significantly higher than that of thin-section CT, T2WI, and unenhanced thick- or thin-section Quick 3D imaging (P < 0.05). DLR is thus considered useful for image quality improvement on MR imaging. STIR imaging and CE-Quick 3D imaging with or without CS were validated as appropriate MR sequences for T-factor evaluation in NSCLC patients.

Clinical Breast MRI-based Radiomics for Distinguishing Benign and Malignant Lesions: An Analysis of Sequences and Enhanced Phases.

Previous studies have used different imaging sequences and different enhanced phases for breast lesion calsification in radiomics. The optimal sequence and contrast enhanced phase is unclear. To identify the optimal magnetic resonance imaging (MRI) radiomics model for lesion clarification, and to simulate its incremental value for multiparametric MRI (mpMRI)-guided biopsy. Retrospective. 329 female patients (138 malignant, 191 benign), divided into a training set (first site, n = 192) and an independent test set (second site, n = 137). 3.0-T, fast spoiled gradient-echo and fast spin-echo T1-weighted imaging (T1WI), fast spin-echo T2-weighted imaging (T2WI), echo-planar diffusion-weighted imaging (DWI), and fast spoiled gradient-echo contrast-enhanced MRI (CE-MRI). Two breast radiologists with 3 and 10 years' experience developed radiomics model on CE-MRI, CE-MRI + DWI, CE-MRI + DWI + T2WI, CE-MRI + DWI + T2WI + T1WI at each individual phase (P) and for multiple combinations of phases. The optimal radiomics model (Rad-score) was identified as having the highest area under the receiver operating characteristic curve (AUC) in the test set. Specificity was compared between a traditional mpMRI model and an integrated model (mpMRI + Rad-score) at sensitivity >98%. Wilcoxon paired-samples signed rank test, Delong test, McNemar test. Significance level was 0.05 and Bonferroni method was used for multiple comparisons (P = 0.007, 0.05/7). For radiomics models, CE-MRI/P3 + DWI + T2WI achieved the highest performance in the test set (AUC = 0.888, 95% confidence interval: 0.833-0.944). The integrated model had significantly higher specificity (55.3%) than the mpMRI model (31.6%) in the test set with a sensitivity of 98.4%. The CE-MRI/P3 + DWI + T2WI model is the optimized choice for breast lesion classification in radiomics, and has potential to reduce benign biopsies (100%-specificity) from 68.4% to 44.7% while retaining sensitivity >98%. 3 TECHNICAL EFFICACY: Stage 2.

Usefulness of T2-Weighted Images with Deep-Learning-Based Reconstruction in Nasal Cartilage.

This study aims to evaluate the feasibility of visualizing nasal cartilage using deep-learning-based reconstruction (DLR) fast spin-echo (FSE) imaging in comparison to three-dimensional fast spoiled gradient-echo (3D FSPGR) images. This retrospective study included 190 set images of 38 participants, including axial T1- and T2-weighted FSE images using DLR (T1WIDL and T2WIDL, belong to FSEDL) and without using DLR (T1WIO and T2WIO, belong to FSEO) and 3D FSPGR images. Subjective evaluation (overall image quality, noise, contrast, artifacts, and identification of anatomical structures) was independently conducted by two radiologists. Objective evaluation including signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) was conducted using manual region-of-interest (ROI)-based analysis. Coefficient of variation (CV) and Bland-Altman plots were used to demonstrate the intra-rater repeatability of measurements for cartilage thickness on five different images. Both qualitative and quantitative results confirmed superior FSEDL to 3D FSPGR images (both p < 0.05), improving the diagnosis confidence of the observers. Lower lateral cartilage (LLC), upper lateral cartilage (ULC), and septal cartilage (SP) were relatively well delineated on the T2WIDL, while 3D FSPGR showed poorly on the septal cartilage. For the repeatability of cartilage thickness measurements, T2WIDL showed the highest intra-observer (%CV = 8.7% for SP, 9.5% for ULC, and 9.7% for LLC) agreements. In addition, the acquisition time for T1WIDL and T2WIDL was respectively reduced by 14.2% to 29% compared to 3D FSPGR (both p < 0.05). Two-dimensional equivalent-thin-slice T1- and T2-weighted images using DLR showed better image quality and shorter scan time than 3D FSPGR and conventional construction images in nasal cartilages. The anatomical details were preserved without losing clinical performance on diagnosis and prognosis, especially for pre-rhinoplasty planning.

Caudolenticular gray bridges of the brain: A magnetic resonance imaging study.

The caudolenticular (or transcapsular) gray bridges (CLGBs) connect the caudate nucleus (CN) and putamen across the internal capsule. The CLGBs function as the main efferent terminus from premotor and supplementary motor area cortex to the basal ganglia (BG). We conjectured if inherent variations in numbers and sizes of CLGBs could contribute to abnormal cortical-subcortical connectivity in Parkinson's disease (PD), a neurodegenerative disorder featuring a hindrance of BG processing. However, there are no literature accounts of normative anatomy and morphometry of CLGBs. We therefore retrospectively analyzed axial and coronal 3T fast spoiled gradient-echo magnetic resonance images (MRIs) of 34 healthy individuals for bilateral CLGBs symmetry, their numbers, dimensions of thickest and longest bridge, and axial surface areas of CN head and putamen. We calculated Evans' index (EI) to account for any brain atrophy. We statistically tested associations between sex or age and measured dependent variables, and linear correlations between all measured variables (significance at p < 0.05). Study subjects were F:M=23:11 with mean age 49.9 years. All EI's were normal (<0.3). All but three CLGBs were bilaterally symmetrical with a mean 7.4 CLGBs per side. Mean CLGBs thickness and lengths were 1.0 and 4.6 mm, respectively; CN head and putamen areas were 205and 382.0 mm2 , respectively. Females had thicker CLGBs (p=0.02) but we found no significant interactions between sex or age and measured dependent variables, and no correlations between CN head or putamen areas and CLGBs dimensions. These normative MRI dimensions of the CLGBs will help guide future studies on the possible role of CLGBs morphometry in PD predisposition.

Two Classes of T1 Hypointense Lesions in Multiple Sclerosis With Different Clinical Relevance.

Background: Hypointense lesions on T1-weighted images have important clinical relevance in multiple sclerosis patients. Traditionally, spin-echo (SE) sequences are used to assess these lesions (termed black holes), but Fast Spoiled Gradient-Echo (FSPGR) sequences provide an excellent alternative.Objective: To determine whether the contrast difference between T1 hypointense lesions and the surrounding normal white matter is similar on the two sequences, whether different lesion types could be identified, and whether the clinical relevance of these lesions types are different.Methods: Seventy-nine multiple sclerosis patients' lesions were manually segmented, then registered to T1 sequences. Median intensity values of lesions were identified on all sequences, then K-means clustering was applied to assess whether distinct clusters of lesions can be defined based on intensity values on SE, FSPGR, and FLAIR sequences. The standardized intensity of the lesions in each cluster was compared to the intensity of the normal appearing white matter in order to see if lesions stand out from the white matter on a given sequence.Results: 100% of lesions on FSPGR images and 69% on SE sequence in cluster #1 exceeded a standardized lesion distance of Z = 2.3 (p < 0.05). In cluster #2, 78.7% of lesions on FSPGR and only 17.7% of lesions on SE sequence were above this cutoff value, meaning that these lesions were not easily seen on SE images. Lesion count in the second cluster (lesions less identifiable on SE) significantly correlated with the Expanded Disability Status Scale (EDSS) (R: 0.30, p ≤ 0.006) and with disease duration (R: 0.33, p ≤ 0.002).Conclusion: We showed that black holes can be separated into two distinct clusters based on their intensity values on various sequences, only one of which is related to clinical parameters. This emphasizes the joint role of FSPGR and SE sequences in the monitoring of MS patients and provides insight into the role of black holes in MS.

Prognostic value of dynamic MRI positive enhancement integral color mapping in osteosynthesis of undisplaced femoral neck fractures.

The common treatment for an undisplaced femoral neck fracture is osteosynthesis. Two major complications of osteosynthesis are non-union and late collapse of the femoral head. We speculated that femoral head perfusion is one of the most important factors that affect the outcome of osteosynthesis after femoral neck fracture. We have preoperatively estimated femoral head perfusion by dynamic MRI positive enhancement integral color mapping (PEICM). The purpose of this study was to evaluate the outcomes of undisplaced femoral neck fractures based on PEICM. Sixty-eight patients participated in this prospective study. All patients underwent PEICM in a 1.5-Tesla MRI machine using coronal fast spoiled gradient echo imaging sequences with gadopentetate dimeglumine as the contrast agent. Femoral head perfusion was displayed via color mapping using PEICM. Three types were distinguished. For type A, the color was identical to unaffected side indicated normal perfusion. For type B, the color was darker than unaffected side indicated decreased perfusion. For type C, the color was black indicated complete absence of perfusion. All patients underwent osteosynthesis with three cannulated screws. The rates of non-union and late collapse for each type were calculated. Sixteen patients were classified as Type A, 43 as Type B, and 6 as Type C. The non-union rates were 0% for Type A, 6.7% for Type B, and 50.0% for Type C. The late collapse rates were 0% for Type A, 4.4% for Type B, and 0% for Type C. PEICM precisely detected femoral head perfusion. Primary prosthetic replacement should be considered for older patients with Type C to minimize the chances of revision surgery, even in undisplaced femoral neck fractures.

The "White Gray Sign" Identifies the Central Sulcus on 3T High-Resolution T1-Weighted Images.

The central sulcus is an important anatomic landmark, but most methods of identifying it rely on variable gyral and sulcal patterns. We describe and assess the accuracy of reduced gray-white contrast along the central sulcus, an observation we term the "white gray sign." We conducted a retrospective review of 51 fMRIs with a T1-weighted 3D inversion recovery fast-spoiled gradient-echo and concomitant hand-motor fMRI, which served as confirmation for the location of the central sulcus. To measure gray-white contrast across the central and adjacent sulci, we performed a quantitative analysis of 25 normal hemispheres along the anterior and posterior cortices and intervening white matter of the pre- and postcentral gyri. 3D inversion recovery fast-spoiled gradient-echo axial images from 51 fMRIs were then evaluated by 2 raters for the presence of the white gray sign as well as additional established signs of the central sulcus: the bracket, cortical thickness, omega, and T signs. The mean gray-white contrast along the central sulcus was 0.218 anteriorly and 0.237 posteriorly, compared with 0.320 and 0.295 along the posterior precentral and anterior postcentral sulci, respectively (P < .001). Both raters correctly identified the central sulcus in all 35 normal and 16 abnormal hemispheres. The white gray sign had the highest agreement of all signs between raters and was rated as present the most often among all the signs. Reduced gray-white contrast around the central sulcus is a reliable sign for identification of the central sulcus on 3D inversion recovery fast-spoiled gradient-echo images.

Abstract W P244: Effect of Remote Limb Ischemic Conditioning on CBF as Measured by Arterial Spin Labeling in Human Stroke

Background: Remote limb ischemic conditioning (RLIC) is a promising treatment for ischemic stroke. We have previously shown that RLIC increases cerebral blood flow, reduces infarct size, and improves outcome in a murine thromboembolic stroke model (Hoda N et al. Stroke. 2012; 43:2794). We hypothesized that RLIC will increase CBF in hypoperfused areas in acute stroke patients as detected by MRI Arterial Spin Labeling (ASL) Methods: Patients with an acute ischemic stroke within 14 days and with a persistent mismatch defined by a perfusion defect measured by ASL that was at least 20% larger than the area of infarction as measured by diffusion weighted imaging (DWI) were eligible. Patients underwent 4 cycles of blood pressure cuff inflation (x200 mm Hg) for 5 minutes and deflation for 5 minutes on the leg or arm, 1- 2 times per day. MRI ASL, DWI, and 3D T1-weighted Fast Spoiled Gradient-Echo (FSPGR) images were taken before and 60 minutes after the last cycle of RLIC to measure CBF. Two neuroradiologists analyzed the images. Results: After 3 of 4 RLIC sessions, the CBF improved and the mismatch decreased by at least 15%. In the one patient without a reduction in mismatch, the RLIC was performed on the arm and not the leg. Conclusions: 1.) RLIC increased CBF as measured by ASL in stroke patients with a persistent diffusion-perfusion mismatch. 2.) Since it can be repeated multiple times on the same patient, ASL may be a useful biomarker of the conditioning response in humans. 3.) Further work in a larger sample of patients is needed to define the optimal regimen of RLIC and to determine the utility of ASL as a biomarker.

MR imaging features and contrast enhancement characteristics in benign and malignant breast lesions

Introduction: Breast cancer is the commonest female malignancy in Malaysia and other countries the world. All races are affected in Malaysia and breast cancer comprised 30.4% of all newly diagnosed cancer cases. A women in Malaysia has a 1 in 19 chances of getting breast cancer in her lifetime. The Age Standardized Rate (ASR) of female breast cancer in Malaysia is 52.8 per 100,000 people and is higher than that in Singapore, Hong Kong and Shanghai, but it is lower than that in Australia and the UK. Out of the 4,337 new cases of female breast cancer cases reported to the National Cancer Registry of Malaysia in 2002, 52.3% were for women less than 50 years old. Genetic risk factors have not been studies thoroughly in Malaysia. Methods: We prospectively studied 55 patients with breast lumps in whom MR imaging was performed. The T1- and T2-weighted, axial STIR, fat-suppression contrast enhanced fast spin echo and two dimensional dynamic enhanced fast spoiled gradient-echo images were obtained. The tumour margins and shape, enhancement pattern and time-signal intensity curves were analysed. Results: A total of 37 patients fulfilled the study criteria with the mean age of 43.46 &plusmn;11.99 years (age ranged 21-70). There were 23 benign and 14 malignant lesions. The MR imaging criteria suggestive of malignancy were poorly defined and spiculated margins, irregular shape, heterogeneous and rim enhancement as well as type II and III curves. On the other hand, the criteria for a benign breast lesions were well-defined margin, regular and lobulated shape, none or homogeneous enhancement and type I curve. Only the malignant lesions are characterised by skin, retroareolar, nipple and pectoralis muscle involvement. Conclusion: MR imaging is a valuable complementary breast imaging tool to further evaluate equivocal findings on conventional x-ray mammography. A combination of lesion morphology and enhancement characteristics is useful in distinguishing benign from malignant lesions. DOI: http://dx.doi.org/10.3126/joim.v34i2.9052 &nbsp; Journal of Institute of Medicine August, 2012; 34:2 28-34

MR imaging features and contrast enhancement characteristics in benign and malignant breast lesions

Introduction: Breast cancer is the commonest female malignancy in Malaysia and other countries the world. All races are affected in Malaysia and breast cancer comprised 30.4% of all newly diagnosed cancer cases. A women in Malaysia has a 1 in 19 chances of getting breast cancer in her lifetime. The Age Standardized Rate (ASR) of female breast cancer in Malaysia is 52.8 per 100,000 people and is higher than that in Singapore, Hong Kong and Shanghai, but it is lower than that in Australia and the UK. Out of the 4,337 new cases of female breast cancer cases reported to the National Cancer Registry of Malaysia in 2002, 52.3% were for women less than 50 years old. Genetic risk factors have not been studies thoroughly in Malaysia. Methods: We prospectively studied 55 patients with breast lumps in whom MR imaging was performed. The T1- and T2-weighted, axial STIR, fat-suppression contrast enhanced fast spin echo and two dimensional dynamic enhanced fast spoiled gradient-echo images were obtained. The tumour margins and shape, enhancement pattern and time-signal intensity curves were analysed. Results: A total of 37 patients fulfilled the study criteria with the mean age of 43.46 ±11.99 years (age ranged 21-70). There were 23 benign and 14 malignant lesions. The MR imaging criteria suggestive of malignancy were poorly defined and spiculated margins, irregular shape, heterogeneous and rim enhancement as well as type II and III curves. On the other hand, the criteria for a benign breast lesions were well-defined margin, regular and lobulated shape, none or homogeneous enhancement and type I curve. Only the malignant lesions are characterised by skin, retroareolar, nipple and pectoralis muscle involvement. Conclusion: MR imaging is a valuable complementary breast imaging tool to further evaluate equivocal findings on conventional x-ray mammography. A combination of lesion morphology and enhancement characteristics is useful in distinguishing benign from malignant lesions. DOI: http://dx.doi.org/10.3126/joim.v34i2.9052 Journal of Institute of Medicine August, 2012; 34:2 28-34

Pelvic magnetic resonance imaging in the ewe: A model for experimental gynecologic research

Our goal was to demonstrate the feasibility of pelvic magnetic resonance imaging (MRI) in the ewe. Two ewes underwent a pelvic 3 Tesla MRI scan, under light anesthesia, with T2-weighted fast spin-echo images and T1-weighted spoiled gradient-echo images. Multiplan T1 weighted images were also obtained after the intravenous injection of a contrast product. One ewe was anestrous and the other one had undergone ovarian stimulation. No incident occurred during the examination. Both the uterus (with two horns) and the ovaries were identified. The intensity of the endometrial, myometrial and ovarian signals was similar to that encountered in women. The uterus and ovaries could be enhanced in both cases. Pelvic vasculature was also studied. In the case of hormonal stimulation, the endometrium was thicker, follicular growth was identified and enhancement seemed greater. MRI in the ewe is feasible and could be helpful in experimental gynecologic research, especially in uterus transplantation.

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

ObjectiveTo 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 designPhase-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). ResultsTreatments 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. ConclusionsAt 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.

Neuropsychiatric Symptoms as a Putative Crescendo Warning of a Striatocapsular Infarct?

Neuropsychiatric Symptoms as a Putative Crescendo Warning of a Striatocapsular Infarct?

Assessment of Carotid Geometry by Using the Contrast-enhanced MR Angiography

Purpose : To evaluate the geometry of carotid artery by assessing the images of contrast-enhanced MR angiography (CE-MRA) and interrelationships between the geometry of carotid artery and clinical factors. Materials and Methods : 216 consecutive patients who performed supraaortic CE-MRA with fast spoiled gradient-echo imaging were included. Their medical records were reviewed for variable information including risk factors predictive of generalized atherosclerotic disease (age, hypertension (HTN), diabetes mellitus, hyperlipidema, and smoking), sex, body weight, height, and body mass index (BMI). We reviewed the CE-MRA with carotid origin (3 types), carotid artery tortuosity, angle of internal carotid artery bifurcation, the type of aortic arch branching, and the presence of the coiling of carotid artery. Results : Multinomial logistic regression analysis showed that significantly contributed clinical backgrounds for carotid origin were the age and the BMI. With an increase of age at 1, the probability that the type of carotid origin become from type 1 to type 2 was 0.9 times (p=0.004) in right carotid artery (RCA), 0.9 times (p = 0.031) in left carotid artery (LCA), 0.9 times that are likely to be type3 from type 2 (pand , respectively. Conclusion : The BMI, age, sex and presence of HTN affects the geometry of carotid arteries, the site of origin and tortuosity of carotid artery specifically.

The use of time to maximum enhancement to indicate areas of ablation following the treatment of liver tumours with high-intensity focused ultrasound

The aim of this study was to investigate the use of time to maximum enhancement (t(max)) for each voxel in contrast-enhanced MRI (CE-MRI) as a non-invasive tool to determine areas of necrosis following treatment of liver tumours with high-intensity focused ultrasound (HIFU) and, having established the utility of t(max) maps, to develop a three-dimensional (3-D) representation to display this information concisely. 3-D T(1) weighted fast spoiled gradient echo images of the liver were acquired before and after administration of contrast agent. The CE-MR images were aligned to the pre-contrast volume and an estimate of t(max) was obtained for each voxel. Such pre- and post-contrast image sets were acquired before and after ablation. The t(max) maps before and after HIFU treatment were correlated with the procedure notes, radiological reports and gross histological specimen. Finally, 3-D t(max) maps of the whole liver were reconstructed to show all areas of abnormal tissue perfusion. Normal, healthy liver tissue uniformly enhances maximally after approximately 1 min. The computed t(max) maps accurately delineated areas of abnormal contrast agent uptake, corresponding to tumour deposits. Changes in t(max) and non-enhancing voxels after treatment correlate well with volumes targeted during ablation and the necrotic regions seen on gross histological specimens. Alignment of the contrast-enhanced images with the pre-contrast volume greatly improved the conspicuity of the t(max) maps. We conclude that t(max) maps and their 3-D views can be used as a non-invasive tool to assess and potentially to quantify the success of HIFU ablation, and concisely represent the large number of CE-MRI data.

The in vivo diagnosis of early‐stage aortic valve sclerosis using magnetic resonance imaging in a rabbit model

To use magnetic resonance imaging (MRI) to identify and monitor early aortic valve sclerosis (AVS) induced by cholesterol feeding in rabbits. AVS is a highly prevalent disease process, affecting more than 25% of the population over age 65. A major obstacle to early stage medical management of AVS has been the lack of an objective noninvasive technique to identify its presence and monitor its progress. Retrospectively gated CINE fast spoiled gradient echo (fSPGR) images of aortic valve cusps were collected at 3-month intervals starting at 6 months using a 1.5 T MR scanner interfaced with a customized surface radiofrequency coil. At 16 months a subset of animals was sacrificed and excised cusps were examined with both high frequency ultrasound (US) and histopathological techniques to validate the MRI method. MR and US analysis identified significant thickening of diseased AV cusps when compared to control (P < 0.05). Histopathological analysis confirmed the presence of human-like AVS in diseased rabbit valves. Early AVS, exemplified by increased valve thickness, can be identified in vivo using high-resolution MRI.

Going to the movies can make all the difference

The upper airway is a complex structure (see Fig. 1). It is a conduit to life, facilitating the basic requirements of breathing and swallowing, as well as higher functions such as speech. Understanding the factors which control the muscles of the upper airway is therefore of major importance, especially so since collapse of the upper airway during sleep is relatively common. Obstructive sleep apnoea (OSA) is the third most common respiratory disorder, after asthma and chronic obstructive airway disease. Moreover the long-term consequences of severe OSA syndrome are considerable. Daytime sleepiness impairs social function and increases accident risk. The cardiovascular risks are also increased with a 10-years predicted occurrence of stroke of 14%, and 23% for myocardial infarction (Kiely & McNicholas, 2000). T1-weighted, magnetic resonance image in a healthy subject The sagittal view shows the tongue and the complexity of the structures surrounding the upper airway. Thirty years ago Remmers et al. published their seminal paper on the ‘pathogenesis of upper airway occlusion during sleep’ (Remmers et al. 1978). The study examined the relationship between the genioglossal electomyogram (EMG) and pharyngeal pressure, and concluded that airway occlusion occurred when the negative pharyngeal pressure exceeded the genioglossus force; the so called ‘balance of forces’. This theory led to a multitude of studies measuring upper airway muscle activation, specifically the muscles of the soft palate and the genioglossus EMG, with the assumption that these are the key muscles for controlling upper airway patency, and that EMG activation is related to muscle stiffening. In this issue of The Journal of Physiology (Cheng et al. 2008) point out that, ‘EMG does not necessarily translate into muscle motion, and the exact mechanism by which the airway is kept patent by the genioglossus is unknown’. Accordingly the EMG may not be the best methodology to capture the functional significance of genioglossal activation, not least because it is a complex structure with multiple fibre directions; indeed few studies have attempted to map the activity of the whole muscle (Eastwood et al. 2003). Cheng et al. (2008) report a technique that provides a method of quantifying the activity of the entire genioglossus muscle. The methodology also allows visualization within the muscle, while providing a high temporal resolution to capture within-breath movements. The technique also advances other imaging modalities, such as endoscopic imaging, which provide information on changes in the size of the airway lumen rather than the surrounding tissues. Cheng et al. have employed fast spoiled gradient echo imaging techniques to reveal how MRI tagging is deformed with tissue motion. Application of this technique to the measurement of genioglossus activity in humans required the ability to monitor breathing with MRI compatible techniques, the development of non-cardiac gated tagging techniques, and the capacity to obtain multiple within breath scans per subject, while analysis of the images involved adaptation of harmonic phase methodology. By combining all these elements the authors have produced a series of great movies illustrating the complexity of the genioglossus activity throughout the respiratory cycle. Watching these movies it is easy to see how a picture is worth a thousand words. However, the value of the images would be limited if there was no way of quantifying the muscle movement seen. It is therefore important to note that authors have also been able to measure the lateral and anterior–posterior displacement of the tongue throughout the respiratory cycle; allowing within- and between-subject comparisons. These data demonstrate that the tongue retains a constant volume throughout the respiratory cycle, albeit redistributed during contraction or compression. To say that the methodology used influences the answers obtained may be an obvious statement when referring to this paper. By developing new methods of visualizing and quantifying genioglossus activity, the authors have opened up the possibility of further understanding the physiological principles of how the upper airway remains patent during the respiratory cycle; how the activity may change under pathological conditions such as those which occur in OSA. Above all the paper illustrates the value of an interdisciplinary approach to produce technological advances that allow new ways of investigating physiology.

MR imaging of medullary carcinoma of the breast

Purpose To examine the magnetic resonance imaging (MRI) findings of medullary carcinoma of the breast and to correlate them with histopathologic features. Materials and methods Eight patients were retrospectively evaluated with pathologically confirmed medullary carcinoma of the breast. T1-weighted fat-saturated, T2-weighted fast spine echo, and gadolinium-enhanced fat-saturated fast spoiled gradient-echo images were obtained. Interpretation of the MRI findings was based on evaluation of the configuration, internal signal intensity, contrast enhancement, and type of the time–intensity curve. Results Medullary carcinoma showed a lobular shape and a smooth margin, either homogenous or heterogeneous enhancement and delayed peripheral enhancement in the late phase on contrast-enhanced MRI, and either a plateau or washout type with rapid initial rise on the time–intensity curve of the dynamic study. Conclusion Although the MRI findings showed a close relationship with histopathologic features of medullary carcinoma, it was difficult to differentiate medullary carcinoma from other histologic types of invasive breast carcinomas.

MENISCI DISPLACEMENT UNDER JOINT LOAD

MENISCI DISPLACEMENT UNDER JOINT LOAD

Changes of Pulmonary Vein Orifice Size and Location throughout the Cardiac Cycle: Dynamic Analysis Using Magnetic Resonance Cine Imaging

Anatomically guided left atrial ablation is used increasingly for treatment of atrial fibrillation (AF). Three-dimensional mapping systems used for pulmonary veins (PV) encircling ablation procedures anticipate a stable size and position of the PV orifice. The aim of the current study was therefore to analyze changes of PV orifice size and location throughout the cardiac cycle using cine magnetic resonance imaging (MRI). Twenty-five healthy volunteers were studied using a 1.5 Tesla MRI system. MR angiograms were acquired with a breath-hold three-dimensional fast-spoiled gradient-echo imaging (3D FSPGR) sequence in the coronal plane before and after gadolinium injection. Maximum intensity projections and multiplanar reformations were performed to reconstruct images of the PV. Bright blood cine imaging in the axial view was acquired by a steady-state free precession pulse sequence. Twenty bright blood images were obtained per cardiac cycle. The axial (anterior-posterior) PV orifice diameter was measured in all 20 images. For analysis of PV movement the location of the orifice posterior edge was plotted on scale paper. PV orifice size depends on the stage of the cardiac cycle with the largest diameter in late atrial diastole and a mean decrease of 32.5% during atrial systole. Location changes of the PV orifice are in the range of up to 7.2 mm and larger in the coronal (lateral-medial) than in the sagittal (anterior-posterior) direction. PV orifice size and location is not as stable as anticipated by three-dimensional mapping systems used for PV encircling left atrial ablation procedures. RF application close to the presumed orifice location should therefore be avoided to minimize the risk of PV stenosis.