Body MR Research Articles

Clinical use of MRI for the evaluation of acute appendicitis during pregnancy.

The purpose of this study was to determine the diagnostic accuracy of MRI for detecting acute appendicitis in pregnancy in a multi-institution study involving general body MR readers with no specific expertise in MR imaging of the pregnant patient. Retrospective review of MRI examinations on PACS in 42 pregnant patients was evaluated for acute right lower quadrant pain. Three fellowship-trained general body radiologists analyzed the MRI examinations in consensus and attempted to localize the appendix, assess for features of appendicitis, and exclude alternative etiologies for the right lower quadrant pain. Of the 42 MRI examinations, the readers noted 6 cases of acute appendicitis, 16 cases of a normal appendix, and 20 cases involving non-visualization of the appendix but where there were no secondary features of acute appendicitis. Based on the surgical data and clinical follow-up, there were 3 true-positive cases, 3 false-positive cases, 34 true-negative cases, and 2 false-negative cases of acute appendicitis on MRI. This yielded an accuracy of 88.1%, sensitivity of 60%, specificity of 91.9%, positive predictive value of 50%, and negative predictive value of 94.4% for the detection of acute appendicitis in the pregnant patient on MRI. Alternative etiologies for the right lower quadrant pain on MRI included torsion of an ovarian dermoid in 1 case and pyelonephritis in 1 case. MRI is an excellent modality for excluding acute appendicitis in pregnant patients presenting with right lower quadrant pain.

Application of spectroscopy (1HMRS) to assess liver metabolite concentrations in rats with intrauterine growth restriction

Objective: Proton magnetic resonance spectroscopy (1H-MRS) measurement of liver metabolism in intrauterine growth restriction rats has seldom been reported. This study investigated the application of 1H-MRS in assessing liver metabolism in newborn pups that experienced intrauterine growth restriction.Methods: Intra-uterine growth restriction was established by feeding rats low-protein diets during pregnancy. Newborn pups received conventional magnetic resonance imaging and 1H-MRS using a 3.0T whole body MR scanner at 3, 8 and 12 weeks post birth.Results: The success rate of 1H-MRS was 83.33%. Significantly lower body weight, BMI and body length at 3 weeks as well as significantly lower body weight, BMI and waist circumference at 8 and 12 weeks were observed in newborn pups of IUGR rats compared with pups of control rats. Significant differences in ACho/H2O, ACr/H2O, AGlx/H2O and ALipid/H2O at 3 and 8 weeks as well as significant differences in ACr/H2O, ALipid/H2O and AGlx/H2O at 12 weeks were observed between pups of control rats and pups of IUGR rats.Conclusion: 1H-MRS allows noninvasive assessment of liver metabolism in the rat and demonstrated the poor liver development of rats that experienced IUGR.

2D radially compensating excitation pulse in combination with an internal transceiver antenna for 3D MRI of the rectum at 7 T.

The high precession frequency in ultrahigh field MRI coincides with reduced RF penetration, increased RF power deposition and consequently can lead to reduced scan efficiency. However, the shorter wavelength enables the use of efficient antennas rather than loop coils. In fact, ultrathin monopole antennas have been demonstrated at 7 T, which fit in natural cavities like the rectum in the human body. As the RF field generated by the antenna provides an extremely nonuniform B1 field, the use of conventional RF pulses will lead to severe image distortions and highly nonuniform contrast. However, using the two predominant dimensions (orthogonal to the antenna), 2D RF pulses can be designed that counteract the nonuniform B1 into uniform flip angles. In this study the authors investigate the use of an ultrathin antenna not only for reception, but also for transmission in 7 T MRI of the rectum. The 2D radially compensating excitation (2D RACE) pulse was designed in matlab. SAR calculations between the 2D RACE pulse and an adiabatic RF pulse (BIR-4) have been obtained, to visualize the gain in decreasing the SAR when using the 2D RACE pulse instead of an adiabatic RF pulse. The authors used the 7 T whole body MR system in combination with an internally placed monopole antenna used for transceiving and obtained 3D gradient echo images with a conventional sinc pulse and with the 2D RACE pulse. For extra clarity, they also reconstructed an image where the receive field of the antenna was removed. Comparing the results of the SAR simulations of the 2D RACE pulse with a BIR-4 pulse shows that for low flip angles (θ < 41°) the SAR can be decreased with a factor of 4.8 or even more, when using the 2D RACE pulse. Relative to a conventional sinc excitation, the 2D RACE pulse achieves more uniform flip angle distributions than a BIR-4 pulse with a smaller SAR increase (16 × versus 64 ×). The authors have shown that the 2D RACE pulse provides more homogeneous flip angles for gradient echo sequences when compared to a conventional sinc pulse albeit at increased SAR. However, when compared to adiabatic RF pulses, as shown by simulations, the SAR of the 2D RACE pulse can be an order of magnitude less. Phantom and in vivo human rectum images are obtained to demonstrate that the 2D RACE pulse can provide a uniform excitation while transmitting with a single ultrathin endorectal antenna at 7 T. The combination of thin rectal antennas with efficient uniform transmit can open up new possibilities in high resolution imaging of rectal cancer.

Body MR angiography in children: how we do it.

Vascular pathology is ubiquitous in children. Common indications for angiographic imaging in the body include congenital anomalies, portal hypertension, assessing resectability of neoplasms, renovascular hypertension, vascular malformations, vasculitis, systemic vein thrombosis, and trauma. MR angiography, with or without the use of intravenous contrast agents, is therefore a mainstay in the repertoire of MR imaging in children. Pediatric contrast-enhanced MR angiography has benefited from several innovations in recent years, including improved hardware options like high-field-strength scanners and integrated high-density coil arrays, new sequences that combine parallel imaging, innovative k-space sampling and Dixon fat suppression with time-resolved imaging, new contrast agents with longer blood-pool residence time, and advanced post-processing solutions like image fusion. This article focuses on the principles of contrast-enhanced MR angiography of the body as it pertains to the physiologies and pathologies encountered in children. It also discusses tools to adapt the MR angiographic technique to the clinical indication, as well as pitfalls of post-processing and interpretation in commonly encountered vascular imaging scenarios in the pediatric body.

Proton Magnetic Resonance Spectroscopy: Relevance of Glutamate and GABA to Neuropsychology.

Proton Magnetic Resonance Spectroscopy (MRS) has been widely used to study the healthy and diseased brain in vivo. The availability of whole body MR scanners with a field strength of 3 Tesla and above permit the quantification of many metabolites including the neurotransmitters glutamate (Glu) and γ-aminobutyric acid (GABA). The potential link between neurometabolites identified by MRS and cognition and behavior has been explored in numerous studies both in healthy subjects and in patient populations. Preliminary findings suggest direct or opposite associations between GABA or Glu with impulsivity, anxiety, and dexterity. This chapter is intended to provide an overview of basic principles of MRS and the literature reporting correlations between GABA or Glu and results of neuropsychological assessments.

Pediatric Body MR Angiography: Principles, Techniques, and Current Status in Body Imaging.

The purpose of this article is to describe the principles and various techniques of MR angiography (MRA) that can be applied to pediatric body imaging and the current noncardiac, nonneurologic applications of MRA of children. The choice between CT angiography and MRA for body imaging should depend on the clinical query, ROI, and vessel size. MRA is useful for assessment of stenosis of the main renal artery, portal hypertension, tumor vascularity, vascular malformations, generalized vasculopathy in vasculitis and syndromes, and thoracic outlet syndrome.

W(h)ither human cardiac and body magnetic resonance at ultrahigh fields? technical advances, practical considerations, applications, and clinical opportunities

The objective of this study was to document and review advances and groundbreaking progress in cardiac and body MR at ultrahigh fields (UHF, B0 ≥ 7.0 T) with the goal to attract talent, clinical adopters, collaborations and resources to the biomedical and diagnostic imaging communities. This review surveys traits, advantages and challenges of cardiac and body MR at 7.0 T. The considerations run the gamut from technical advances to clinical opportunities. Key concepts, emerging technologies, practical considerations, frontier applications and future directions of UHF body and cardiac MR are provided. Examples of UHF cardiac and body imaging strategies are demonstrated. Their added value over the kindred counterparts at lower fields is explored along with an outline of research promises. The achievements of cardiac and body UHF-MR are powerful motivators and enablers, since extra speed, signal and imaging capabilities may be invested to overcome the fundamental constraints that continue to hamper traditional cardiac and body MR applications. If practical obstacles, concomitant physics effects and technical impediments can be overcome in equal measure, sophisticated cardiac and body UHF-MR will help to open the door to new MRI and MRS approaches for basic research and clinical science, with the lessons learned at 7.0 T being transferred into broad clinical use including diagnostics and therapy guiding at lower fields. Copyright © 2015 John Wiley & Sons, Ltd.

Accuracy and reproducibility of adipose tissue measurements in young infants by whole body magnetic resonance imaging.

PurposeMR might be well suited to obtain reproducible and accurate measures of fat tissues in infants. This study evaluates MR-measurements of adipose tissue in young infants in vitro and in vivo.Material and MethodsMR images of ten phantoms simulating subcutaneous fat of an infant’s torso were obtained using a 1.5T MR scanner with and without simulated breathing. Scans consisted of a cartesian water-suppression turbo spin echo (wsTSE) sequence, and a PROPELLER wsTSE sequence. Fat volume was quantified directly and by MR imaging using k-means clustering and threshold-based segmentation procedures to calculate accuracy in vitro. Whole body MR was obtained in sleeping young infants (average age 67±30 days). This study was approved by the local review board. All parents gave written informed consent. To obtain reproducibility in vivo, cartesian and PROPELLER wsTSE sequences were repeated in seven and four young infants, respectively. Overall, 21 repetitions were performed for the cartesian sequence and 13 repetitions for the PROPELLER sequence.Results In vitro accuracy errors depended on the chosen segmentation procedure, ranging from 5.4% to 76%, while the sequence showed no significant influence. Artificial breathing increased the minimal accuracy error to 9.1%. In vivo reproducibility errors for total fat volume of the sleeping infants ranged from 2.6% to 3.4%. Neither segmentation nor sequence significantly influenced reproducibility.ConclusionWith both cartesian and PROPELLER sequences an accurate and reproducible measure of body fat was achieved. Adequate segmentation was mandatory for high accuracy.

Age- and gender-related normal left ventricular deformation assessed by cardiovascular magnetic resonance feature tracking.

BackgroundAssessment of left (LV) ventricular function is one of the most important tasks of cardiovascular magnetic resonance (CMR). Impairment of LV deformation is a strong predictor of cardiovascular outcome in various cardiac diseases like ischemic heart disease or cardiomyopathies. The aim of the study was to provide reference values for myocardial deformation derived from the CMR feature tracking imaging (FTI) algorithm in a reference population of healthy volunteers.MethodsFTI was applied to standard short axis and 2-, 3- and 4-chamber views of vector-ECG gated CMR cine SSFP sequences of 150 strictly selected healthy volunteers (75 male/female) of three age tertiles (mean age 45.8yrs). Global peak and mean radial, circumferential and longitudinal endo- and myocardial systolic strain values as well as early diastolic strain rates were measured using FTI within a standard protocol on a 1.5T whole body MR scanner.ResultsGlobal peak systolic values were 36.3 ± 8.7% for radial, −27.2 ± 4.0% for endocardial circumferential, −21.3 ± 3.3% for myocardial circumferential, −23.4 ± 3.4% for endocardial longitudinal and −21.6 ± 3.2% for myocardial longitudinal strain. Global peak values were -2.1 ± 0.5s−1 for radial, 2.1 ± 0.6s−1 for circumferential endocardial, 1.7 ± 0.5s−1 for circumferential myocardial, 1.8 (1.5-2.2)s−1 for longitudinal endocardial, 1.6 (1.4-2.0)s−1 for longitudinal myocardial early diastolic strain rates. Men showed a higher radial strain than women whereas the circumferential and longitudinal strains were lower resulting in less negative values. Circumferential and longitudinal strain rates were significantly higher in female subjects. Radial strain increased significantly with age whereas the diastolic function measured by the radial, circumferential and longitudinal strain rates showed a decrease.The coefficients of variation determined in ten further subjects, who underwent two CMR examinations within 12 days, were −4.8% for circumferential and −4.5% for longitudinal endocardial mean strains.ConclusionsMyocardial deformation analysis using FTI is a novel technique and robust when applied to standard cine CMR images providing the possibility of a reliable, objective quantification of global LV deformation. Since strain values and strain rates differed partly between genders as well as between age groups, the application of specific reference values as provided by this study is recommendable.

Ferumoxytol as an off-label contrast agent in body 3T MR angiography: a pilot study in children.

Ferumoxytol is an ultrasmall superparamagnetic iron oxide (USPIO) nanoparticle agent used to treat iron deficiency anemia in adults with chronic kidney disease. We aim to determine the feasibility of using ferumoxytol for clinical pediatric cardiac and vascular imaging. We retrospectively identified 23 consecutive children who underwent MRI with ferumoxytol (11 males; mean age: 7.4years, range: 3days-18years), yielding 12 abdominal MR angiography and 15 cardiac MRI studies. Medical records were reviewed for the clinical indication, ferumoxytol dose, injection rate, sedation and any complication. A two-reader consensus scored the images on a five-point scale for overall image quality and delineation of various anatomical structures. Signal-to-background ratios for abdominal aorta and inferior vena cava for abdominal cases and blood pool-myocardium contrast ratios for cardiac cases were calculated. The confidence intervals for obtaining a score of three or above for each image parameter were calculated by using adjusted Wald method. For abdominal MR angiography, average scores for overall image quality, as well as delineation of the hepatic artery, superior mesenteric artery, renal artery and veins were 4.5, 4.3, 4.3, 3.7 and 4.7, respectively. For cardiac exams, the average scores for overall image quality, systemic arteries, pulmonary arteries, pulmonary veins, valves and ventricles were 4.4, 4.6, 4.1, 4.8, 4.1 and 4.7, respectively. For all parameters, the lower bound for the proportion of cases to have a score of 3 or above was 65%. Signal-to-background ratios for aorta and abdominal veins averaged 86 +/- 74 and 86 +/- 77 for full-dose images, and 23 and 18 for half-dose images, respectively. Mean blood pool to myocardium contrast ratio was 3:3. Ferumoxytol can provide excellent image quality for pediatric body MR angiography/MR venography at a dose of 1.5 or 3mg Fe/kg. Further investigation should be directed toward understanding the lowest dose that can be administered.

The utility of deformable image registration for small artery visualisation in contrast-enhanced whole body MR angiography

PurposeAn investigation was carried out into the effect of three image registration techniques on the diagnostic image quality of contrast-enhanced magnetic resonance angiography (CE-MRA) images. MethodsWhole-body CE-MRA data from the lower legs of 27 patients recruited onto a study of asymptomatic atherosclerosis were processed using three deformable image registration algorithms. The resultant diagnostic image quality was evaluated qualitatively in a clinical evaluation by four expert observers, and quantitatively by measuring contrast-to-noise ratios and volumes of blood vessels, and assessing the techniques' ability to correct for varying degrees of motion. ResultsThe first registration algorithm (‘AIR’) introduced significant stenosis-mimicking artefacts into the blood vessels' appearance, observed both qualitatively (clinical evaluation) and quantitatively (vessel volume measurements). The two other algorithms (‘Slicer’ and ‘SEMI’), based on the normalised mutual information (NMI) concept and designed specifically to deal with variations in signal intensity as found in contrast-enhanced image data, did not suffer from this serious issue but were rather found to significantly improve the diagnostic image quality both qualitatively and quantitatively, and demonstrated a significantly improved ability to deal with the common problem of patient motion. ConclusionsThis work highlights both the significant benefits to be gained through the use of suitable registration algorithms and the deleterious effects of an inappropriate choice of algorithm for contrast-enhanced MRI data. The maximum benefit was found in the lower legs, where the small arterial vessel diameters and propensity for leg movement during image acquisitions posed considerable problems in making accurate diagnoses from the un-registered images.

EX VIVO METABOLIC SIGNATURES OF GLIOMAS BASED UPON TUMOR GRADE, IMAGING CHARACTERISTICS AND TREATMENT HISTORY

BACKGROUND: The purpose of this study was to use ex vivo NMR spectroscopy of image guided tissue samples in order to characterize the metabolic signatures of gliomas and to determine which in vivo parameters are likely to be of interest for directing treatment, evaluating response and predicting outcome. METHODS: A total of 254 image guided tissue samples were obtained from 126 patients with glioma who were undergoing surgical resection for either a new or recurrent lesion. Half of each sample was flash frozen for analysis using ex vivo high resolution magic angle spinning (HRMAS) 1H spectroscopy with a 500MHz NMR scanner. Metabolite levels were estimated from the ex vivo spectra using the HR-QUEST software package. The other half of each sample was fixed in paraffin for subsequent histological analysis. Confirmation of the presence of tumor, the definition of tumor grade and evaluation of histology were made by an experienced pathologist. Associations between samples with different pathologies and/or from different anatomic regions were evaluated using a proportional odds logistic regression model with repeated measures in order to take account of the multiple samples per subject. RESULTS: Significant differences in the ex vivo metabolite levels were observed between samples from groups that were separated based upon (i) primary tumor grade, (ii) IDH status, (iii) having arisen as primary vs secondary GBM, (iv) being classified as corresponding to recurrent GBM vs treatment effect and (v) coming from regions of GBM that were contrast enhancing versus non-enhancing on T1-weighted post-Gadolinium images. Key metabolites that were relevant for making distinctions between the various groupings included levels of 2-hydroxglutarate, myo-inositol, phosphocholine, glycerophosphcholine, glutathione, glycine, glutamate, creatine, N-acetylasparate and mobile lipids. CONCLUSIONS: Many of the metabolites that were highlighted as being associated with different pathologies and regional imaging characteristics can be measured using clinically available 3T whole body MR scanners in conjunction with in vivo 1H MR spectroscopic imaging. Recent advances in the methodology for acquiring and analyzing such data have made it possible to obtain maps of metabolite levels from the brain in a scan time of 5-10 minutes. Applications to patient care include assessment of tumor burden, prediction of outcome and tailoring treatment to individual patient characteristics.Supported by: NIH P50 {type:entrez-nucleotide,attrs:{text:CA097257,term_id:34950564,term_text:CA097257}}CA097257, RO1 {type:entrez-nucleotide,attrs:{text:CA127612,term_id:35007666,term_text:CA127612}}CA127612 and P01 CA118816. SECONDARY CATEGORY: Neuropathology & Tumor Biomarkers.

Diffusion-weighted imaging in pediatric body MR imaging: principles, technique, and emerging applications.

Diffusion-weighted (DW) imaging is an emerging technique in body imaging that provides indirect information about the microenvironment of tissues and lesions and helps detect, characterize, and follow up abnormalities. Two main challenges in the application of DW imaging to body imaging are the decreased signal-to-noise ratio of body tissues compared with neuronal tissues due to their shorter T2 relaxation time, and image degradation related to physiologic motion (eg, respiratory motion). Use of smaller b values and newer motion compensation techniques allow the evaluation of anatomic structures with DW imaging. DW imaging can be performed as a breath-hold sequence or a free-breathing sequence with or without respiratory triggering. Depending on the mobility of water molecules in their microenvironment, different normal tissues have different signals at DW imaging. Some normal tissues (eg, lymph nodes, spleen, ovarian and testicular parenchyma) are diffusion restricted, whereas others (eg, gallbladder, corpora cavernosa, endometrium, cartilage) show T2 shine-through. Epiphyses that contain fatty marrow and bone cortex appear dark on both DW images and apparent diffusion coefficient maps. Current and emerging applications of DW imaging in pediatric body imaging include tumor detection and characterization, assessment of therapy response and monitoring of tumors, noninvasive detection and grading of liver fibrosis and cirrhosis, detection of abscesses, and evaluation of inflammatory bowel disease.

Optimization of Brain T2 Mapping Using Standard CPMG Sequence In A Clinical Scanner

Abstract In magnetic resonance imaging, transverse relaxation time (T2) mapping is a useful quantitative tool enabling enhanced diagnostics of many brain pathologies. The aim of our study was to test the influence of different sequence parameters on calculated T2 values, including multi-slice measurements, slice position, interslice gap, echo spacing, and pulse duration. Measurements were performed using standard multi-slice multi-echo CPMG imaging sequence on a 1.5 Tesla routine whole body MR scanner. We used multiple phantoms with different agarose concentrations (0 % to 4 %) and verified the results on a healthy volunteer. It appeared that neither the pulse duration, the size of interslice gap nor the slice shift had any impact on the T2. The measurement accuracy was increased with shorter echo spacing. Standard multi-slice multi-echo CPMG protocol with the shortest echo spacing, also the smallest available interslice gap (100 % of slice thickness) and shorter pulse duration was found to be optimal and reliable for calculating T2 maps in the human brain.

Mitigating transmit B 1 inhomogeneity in the liver at 7T using multi-spoke parallel transmit RF pulse design.

In this work, the use of multi-spoke slice-selective parallel transmit (pTX) RF pulse was explored to address B 1+ inhomogeneity in the largest transverse section of the liver at 7T. The impact of the number of spokes was specifically investigated, considering RF pulses consisting of 2, 3 and 4 spokes, as well as single-spoke RF pulses corresponding to static B 1 shimming. Healthy volunteers were imaged on a whole body MR scanner equipped with an eight-channel transmit system. A robust and fast transmit B 1 (B 1+) estimation method was employed to obtain the eight-channel B 1+ maps within a single breath hold. Gradient echo (GRE) images of the liver were acquired using the four different RF pulses and the results were compared. The use of static B 1 shimming (i.e., 1-spoke RF pulse) resulted in partial improvement but significant signal dropouts were still observed in the target region. By comparison, the use of multi-spoke pTX RF pulse design gave rise to much improved excitation homogeneity without signal dropouts. These results demonstrate the effectiveness of multi-spoke pTX RF pulse design in B 1+ homogenization for liver magnetic resonance imaging (MRI) at 7T. The current findings at 7T may have implications for body imaging applications in clinical settings at 3T where B 1+ inhomogeneities are also known for degrading image quality in the torso.

Enhancement patterns in the fibro cellular tissue in different kinds of plaques of the internal carotid artery

BackgroundThe differentiation between stable and vulnerable plaques in the internal carotid artery (ICA) remains a matter of interest. With the implementation of contrast agent in magnetic resonance imaging (MRI) a more detailed plaque characterization is possible. The study at hand focuses on enhancement patterns of fibro cellular tissue in different kinds of plaques in the ICA. MethodsBetween May 2011 and December 2012, 49 patients (39 male) with >50% stenosis of the ICA were consecutively enrolled. In 10 patients with bilateral ICA stenosis, both plaques were included for analysis. We performed a classification of plaques according to Cai and observed 11 type 4–5 plaques, 15 type 6 plaques and 33 type 8 plaques. MRI was performed on a 3T whole body MR system. The standard 12 channel head coil was combined with the neck extension coil and two bilateral 7cm loop coils. Post-contrast T1w images were subtracted from pre contrast images to identify late enhancement in fibro cellular tissue. Enhancement patterns were allocated as intraluminal, intraplaque and vasa vasorum enhancement in different types of plaques. ResultsFibro cellular tissue always exhibited a higher contrast enhancement compared to the sternocleidomastoid muscle. This reflects a higher grade of vascularization of the fibrocellular tissue. Contrast enhancement was present irrespective of the plaque type. In detail, intraluminal, intraplaque and vasa vasorum enhancement were observed in all types of plaques. Even type 8 plaques, according to the classification of Cai, had a significant contrast enhancement, though supposed to be with low inflammatory activity. ConclusionType 8 plaques might not be as stable as postulated. Whether the relevant uptake of contrast agent is due to the fibrous tissue or reflects the inflammatory activity of the plaque should be matter of further investigations.

SAT0397 High bone turnover assessed by 18F-fluoride PET/CT in the spine of patients with ankylosing spondylitis: No redundancy to inflammatory lesions detected by whole body MRI

BackgroundThe current paradigm of radiographic progression in ankylosing spondylitis involves resolution of an inflammatory lesion and its replacement by fat tissue followed by cartilage metaplasia and endochondral ossification. However, syndesmophytes...

Body MR Imaging at 3 Tesla

Body MR Imaging at 3 Tesla

A Comparative Study between Whole Body Magnetic Resonance Imaging and Bone Scintgraphy in Detection of Bone Metastases in Patients with Known Breast or Lung Cancer

Purpose: The aim of this work is to compare the ability of whole body MRI including diffusion study with that of 99m Tc-Methylene Diphosphonate Scintigraphy to detected skeletal metastases in patients with breast and lung cancer. Patients and methods: 60 patients comprising 38 females and 22 males ranging in age from 30 to 60 years with a mean age of 48.1 years (mean age 47.3 years for females and 49 years for males) were enrolled in the study. 29 females are histopathologically proven cases of breast malignancy, 9 females and the 22 males are histopathologically proven cases of lung cancer. The patients were referred from Oncological departments to perform the whole body MR study and bone scan at Ain Shams University hospitals MRI units and a private center during the time interval from December 2008 till December 2012. All patients were subjected to both whole body MRI and bone scintigraphy. The whole body MRI was mainly obtained using 4 contiguous coronal stations for body coverage using the body coil and 2 contiguous sagittal stations for the spine using T1W FSE and STIR sequences. 48 out of 60 patients toke IV contrast and post contrast T1W imagaes with fat suppression were taken. The MRI examinations were performed using a superconducting 1.5 Tesla magnet (Achieva: Philips Medical Systems). Standard skeletal Scintigraphy was performed using a planar one phase technique (delayed phase). The examination was done 2-3 hours after IV injection of technicium 99m labeled Methylene Diphosphonate with a maximum dose of 20 mCi. Results: 42 patients out of 60 were positive for metastases based on histopathological verification or follow up. On MRI, 39 patients had metastases, 3 were false negative, 12 were true negative and 6 were false positive. On bone scan, 35 were true positive, 7 were false negative, 4 were false positive and 14 were true negative. Based on lesion detection, on comparing bone scan to WB-MRI with and without diffusion, bone scan had an overall sensitivity of 85.6%, specificity 67.5 %, PPV 61.7% and NPV 66.3%, while WB-MRI had statistical values of 73.4%, 68.8%, 78.1% and 62.6% respectively. On adding DWI, values raised to 88.9%, 82.9%, 93% and 69% respectively. Quantitative analysis of DWI was also included in this study revealing an overlap between the Low ADC values of red marrow and metastasis at the range of 0.61 to 0.69 x10-3 mm2/sec and then between metastasis and other benign pathological marrow entities at the range of 0.9 to 1.03 x 10-3 mm2/sec. WB-MRI also detected 64 soft tissue metastatic lesions which became 71 lesions on adding DWI with a distribution of hepatic, pulmonary, brain, adrenal, lymph nodes, pleural, leptomeningeal and renal lesions. Conclusion: we don't think that WB-MRI should replace bone scan in the quest for skeletal metastases. However, we believe that WB-MRI should be the modality of choice when both skeletal and soft tissue metastases are suspected and in the follow up of a known metastatic patients for adequate coverage of both skeletal and soft tissue structures combined with qualitative and quantitative features of DWI helping assess tumors at cellular levels even prior to gross morphological changes verifying response to therapy as early as possible sparing patients precious time from drifting with delayed decision making.

Normal paediatric bone marrow: Magnetic resonance imaging appearances from birth to 5 years

Bone marrow (BM) assessment is an important aspect of paediatric MRI, with the marrow cavity visible on almost every clinical MR examination. In practice, however, assessment for marrow infiltration in paediatric patients can be challenging. Our aim was to review the MRI appearance of normal BM from 0 to 5 years. Consecutive body MR examinations over 7 years were retrospectively reviewed in patients aged 0-5 years. Patients with anticipated BM abnormality were excluded. All patients had imaging of the spine and/or pelvis with T1-weighted (T1) ± T2 with fat saturation, post-contrast T1-weighted, diffusion-weighted or out-of-phase sequences. Nineteen patients were included: nine (47%) infants, 11 (58%) boys, mean age 18.2 months (range 1 day to 3 years and 10 months). On T1 imaging, 69% infant marrow sites and 24% in children >1 year were isointense, the remainder were hyperintense. One hundred per cent BM was T2 fat saturation hyperintense. Enhancement following contrast was seen in 16% of BM sites. Restricted diffusion was seen in 100% infant BM and 50% BM in children >1 year. On out-of-phase imaging, no signal loss was seen in infants, and 21% BM in children >1 year showed signal loss. Due to normal age-related differences in BM histology, MRI for marrow assessment in infants and young children can be misleading and may mimic marrow infiltration.