Insights into quantitative diffusionweighted mri for. Conventional diffusionweighted imaging dwi is typically performed using a singleshot. All analyses were performed with software sas, version 9. Diffusionweighted magnetic resonance imaging with echoplanar. Fiftysix mr imaging studies were performed from 2005.
The epi sequence can be collected as a blipped or nonblipped technique. C, at this location, increased dw signal intensity is shown on the transverse nonepi dwi sequence, indicative of cholesteatoma. Diffusion refers to the random, microscopic movement of water and other small molecules due to thermal collisions. The diagnostic accuracy of nonechoplanar diffusion. Purpose and background this study retrospectively compares diagnostic performance of 1. Artifacts related to airbone interface in the mastoid region may represent a relevant limitation to the utilization of echoplanar diffusionweighted imaging. Stationary spins are not affected by the paired gradients, but diffusing spins are dephased. The diffusion weighted epi sequence is very similar to a spin echo sequence. Another scheme which is sometimes used, especially in brain scanning or where images are needed very rapidly, is called echoplanar imaging epi. Despite its good diagnostic performance, there are recognised.
Methods patients with clinically suspected recurrent cholesteatoma or postoperative routine survey mr who subsequently underwent surgical. We evaluated the diagnostic accuracy, expressed as a positive predictive value, of mr imaging for the detection of residual andor recurrent cholesteatoma in our hospital. We have made use of the following external software sources, and would like to thank their creators. Diffusionweighted mri dwmri is a powerful tool for the detection of cholesteatoma. This unique activation gives this sequence a unique beeping sound. Contemporary nonechoplanar diffusionweighted imaging of. The b matrix in diffusion tensor echoplanar imaging james mattiello, peter j. Diffusionweighted magnetic resonance imaging of the temporal bone. This, combined with an oscillating gradient system in the frequency encoding direction, produces a zigzag trajectory in kspace. All mri data were processed offline with software packages. Pdf nonechoplanar diffusion weighted imaging in the. This is accomplished by rapidly reversing the readout or frequency encoding gradient. Echo planar imaging is performed using a pulse sequence in which multiple echoes of different phase steps are acquired using rephasing gradients instead of repeated 180 degree radio frequency pulses following the 90180 in a spin echo sequence. By far the most commonly used technique relies on a spinecho echoplanar sequence seepi although nonepi techniques e.
Quiet echo planar imaging for functional and diffusion mri. Abdominal mri advances in the detection of liver tumours. The difference lies in a unique gradient activation at different amplitudes prior. We examine the clinical impetus for wholebody diffusionweighted mri and discuss how to implement the technique with clinical mri systems. The fusion process was performed by an otolaryngologic surgeon with minimal software experience. The aim of this study was to assess the utility of epidwi and nonepi.
Another scheme which is sometimes used, especially in brain scanning or where images are needed very rapidly, is called echo planar imaging epi. Our aim was to assess the usefulness of magnetic resonance imaging mri with spinecho echoplanar diffusionweighted sequences seepidwi in the study of primary and secondary softtissue tumours by correlating the results of imaging and histology. Non epi dwi is a promising alternative to secondlook surgery for the detection of residual andor recurrent cholesteatoma. Echo planar imaging mri pulse sequence presentation youtube. Nonechoplanar diffusion weighted imaging in the detection of. Nonechoplanar diffusion weighted imaging in the detection of postoperative middle ear cholesteatoma. Echo planar imaging an overview sciencedirect topics. More recently the term has been expanded to include any rapid gradientecho or spinecho sequence in which k space is traversed in one or a small number of excitations.
Masking in tortoise uses the bet2 algorithm from the fmrib group, available in fsl. Home bjropen previous issues volume 1, issue 1 cholesteatoma. The diagnostic accuracy of nonechoplanar diffusionweighted. Diffusionweighted echoplanar mri of the brain with calculated adcs. In particular at 3 t, bulk susceptibility artifacts can markedly degrade diffusion weighted images, rendering them non diagnostic. To qualitatively and quantitatively evaluate image quality and compare the diagnostic value of nonechoplanar diffusionweighted imaging dwi based on turbo spinecho tse and echoplanar imaging epi, to distinguish rnpc from postchemoradiation fibrosis.
When the echo planar imaging acquisition strategy is used, the complete image is formed from a single data sample all kspace. This video may be a great help for medical imaging technology students and radiology students as well as those interested. Runge, roman guggenberger, accelerated magnetic resonance diffusion tensor imaging of the median nerve using simultaneous multislice echo planar imaging with blipped caipirinha, european radiology, 2016, 26, 6, 1921crossref. Aug 24, 2016 non echoplanar diffusion weighted magnetic resonance imaging dwi has established itself as the modality of choice in detecting and localising postoperative middle ear cleft cholesteatoma. Epi generates a single 2d image in a fraction of a second. Are adc values of readoutsegmented echoplanar diffusion. Echo planar imaging is performed using a pulse sequence in which multiple echoes of different. This feature can be used in many ways, with a simplistic but very clinically relevant application illustrated.
Statistical analysis was performed with jmp software jmp 14. Non echo planar, diffusionweighted magnetic resonance imaging periodically rotated overlapping parallel lines with enhanced reconstruction sequence compared with echo planar imaging for the detection of middleear cholesteatoma. Multishot readout segmented echoplanar imaging rsepi and echoplanar imaging with reduced fieldofview rfovepi are new, revolutionary techniques for obtaining highquality, distortionminimized diffusionweighted images of challenging body regions, such as the head and neck area, in clinically acceptable acquisition times fig. May 01, 2001 echoplanar imagingcapable mr imaging systems provide improved performance of nonechoplanar imaging sequences due to their enhanced gradient capabilities, fig 17. Non epi dwi is a promising alternative to secondlook surgery for the. Nonechoplanar imaging nonepi mri has been recently introduced to improve the. Non echo planar diffusion weighted magnetic resonance imaging is superior to routine echo planar diffusion weighted magnetic resonance imaging as it minimises susceptibility artefacts. As shown on figures 1a to 1e, at ct, the patient with postmastoidectomy residual cholesteatoma presents a mass with soft tissue density obstructing the surgical cavity which, at magnetic resonance imaging mri, demonstrated diffusion restriction at non echo planar imaging. Diffusion weighted imaging radiology reference article. This is done by using rapidly alternating phase and frequency coding gradient activations. Improving diffusion mri using simultaneous multislice. Diffusion mri measurements in challenging head and brain.
It allows the mapping of the diffusion process of molecules, mainly water, in biological tissues, in vivo and noninvasively. This switching or reversal may also be done in a sinusoidal. Accelerated magnetic resonance diffusion tensor imaging of the median nerve using simultaneous multislice echo planar imaging with blipped caipirinha, european radiology, 2016, 26, 6. Conventional diffusionweighted imaging dwi is typically performed using a singleshot echoplanar ssepi sequence. Green berets ultralight bug out bag with gear recommendations duration. We aimed to investigate the ability of readoutsegmented echo planar imaging rsepibased diffusion tensor imaging dti in assessing the microstructural change of extraocular muscles eoms and optic nerves in patients with thyroidassociated orbitopathy tao as well as in evaluating disease activity. Echoplanar imaging is a very fast magnetic resonance mr imaging technique capable of acquiring an entire mr image in only a fraction of a second. The b matrix in diffusion tensor echoplanar imaging. The nonlinear tensor fitting algorithm uses the mpfit routine from the markwardt idl library, written by craig markwardt. Fusion of computed tomography and propeller diffusion. In singleshot echoplanar imaging, all the spatialencoding data of an image can be obtained after a single radiofrequency excitation. Jun 27, 2012 non echo planar, diffusionweighted magnetic resonance imaging periodically rotated overlapping parallel lines with enhanced reconstruction sequence compared with echo planar imaging for the detection of middleear cholesteatoma.
Nonecho planar diffusionweighted imaging in cholesteatoma radiol bras. Readoutsegmented echoplanar imaging in diffusion weighted mr imaging in breast cancer. Cholesteatoma imaging using modified echoplanar diffusion. Nonechoplanar diffusionweighted mri in children and adolescents. Nonechoplanar diffusion weighted magnetic resonance imaging dwi has established itself as the modality of choice in detecting and localising. Over the past decade, numerous imaging studies have been performed looking into detection of cholesteatomas, investigating both echo planar imaging epi and nonepi dwi sequences. American journal of neuroradiology march 2012, 33 3 439444. Improving diffusion mri using simultaneous multislice echo planar imaging. Peripheral enhancement is observed at delayed phase 45 minutes after. Epi echo planar imaging is one of the early magnetic resonance imaging sequences also known as intascan, used in applications like diffusion, perfusion, and functional magnetic resonance imaging. Diffusionweighted magnetic resonance imaging dwi or dwmri is the use of specific mri sequences as well as software that generates images from the resulting data that uses the diffusion of water molecules to generate contrast in mr images. The diagnostic accuracy of nonechoplanar diffusionweighted imaging in the detection of residual andor recurrent cholesteatoma of.
With recent technical advances in hardware, software, and intravenous contrast agents, mri has evolved into a clinically useful procedure to detect and characterise liver tumours. By far the most commonly used technique relies on a spin echo echo planar sequence seepi although non epi techniques e. Readoutsegmented echo planar imaging in diffusion weighted mr imaging in breast cancer. The diagnostic accuracy of non echo planar diffusion weighted imaging in the detection of residual andor recurrent cholesteatoma of the temporal bone m. Nonechoplanar diffusion weighted imaging in the detection of post. Diffusion weighted imaging dwi is well established as a valuable technique for the diagnosis of acute infarction that provides high sensitivity and specificity. In particular at 3 t, bulk susceptibility artifacts can markedly degrade diffusionweighted images, rendering them nondiagnostic. We examine the clinical impetus for wholebody diffusion weighted mri and discuss how to implement the technique with clinical mri systems. The combination of mri systems with larger gradients, improved surface coils, and parallel imaging techniques have produced substantial improvements in mri quality and speed of image acquisition. To investigate the diagnostic value of nonecho planar diffusionweighted magnetic resonance imaging dwmri for primary and recurrentresidual postoperative cholesteatoma in adults. Echo planar imaging epi is the fastest imaging sequence currently available and has the potential to revolutionize many aspects of mr technology.
Advances in gradient and digital data acquisition technology have made it possible to obtain individual mr slices in the time frame of 50100 msec, thus minimizing the effects of patient motion. This is typically an echoplanar sequence using rapidly oscillating phase and frequency gradients that generate multiple gradient. Schlaier j, bretschneider t, schuierer g, feuerbach s. It is a rapid mri technique that is capable of producing tomographic images at video rates. Singleshot and segmented 2d3d seepi, maxwell term corrected irepi and fidepi for diffusion imaging, perfusion imaging and ultra fast t2 weighted 2d and 3d anatomical imaging. Diffusionweighted imaging of the appendicular skeleton. Conventional diffusion weighted imaging dwi is typically performed using a singleshot echo planar ssepi sequence. Oct 12, 2016 mri scanner audio sound of gradient echo planar. We aimed to investigate the ability of readoutsegmented echoplanar imaging rsepibased diffusion tensor imaging dti in assessing the microstructural change of extraocular muscles eoms and optic nerves in patients with thyroidassociated orbitopathy tao as well as in evaluating disease activity.
Readoutsegmented echoplanar diffusionweighted imaging resolve provides. Non echo planar, diffusion weighted magnetic resonance imaging periodically rotated overlapping parallel lines with enhanced reconstruction sequence compared with echo planar imaging for the detection of middleear cholesteatoma. To qualitatively and quantitatively evaluate image quality and compare the diagnostic value of non echo planar diffusion weighted imaging dwi based on turbo spin echo tse and echo planar imaging epi, to distinguish rnpc from postchemoradiation fibrosis. Resolve, multishot echoplanar diffusion weighted imaging. Generically, this acquisition mode is known as echoplanar imaging epi. The diagnostic accuracy of nonechoplanar diffusionweighted imaging in the detection of residual andor recurrent cholesteatoma of the temporal bone m.
As originally defined, echo planar imaging referred to a sequence in which data from all of kspace for an entire 2d plane was collected following a single rfexcitation pulse. Evaluation of diffusion weighted mri sequence as a predictor of. The echo planar epi is the fastest acquisition method in mri 100 ms slice, but with limited spatial resolution. Nonechoplanar imaging epi mri has been recently introduced to improve the detection of smallsized cholesteatoma and decrease different artefacts occurring in the epidiffusionweighted dw. Comparison with singleshot echoplanar imaging in image quality yun ju kim, md, 1 sung hun kim, md, 1 bong joo kang, md, 1 chang suk park, md, 2 hyeon sook kim, md, 3 yo han son, meng, 4 david andrew porter, phd, 5 and byung joo song, md 6. Non echo planar imaging epi mri has been recently introduced to improve the detection of smallsized cholesteatoma and decrease different artefacts occurring in the epi diffusion weighted dw. Nagai n, tono t, matsuda k, toyama k, kawano h, kodama t 2008 value of non echo planar diffusion weighted magnetic resonance imaging in the detection of middle ear cholesteatomea. This video describes the epi, the fastest technique in mri pulse sequence. This video may be a great help for medical imaging technology students and radiology students as. Potential value of nonechoplanar diffusionweighted imaging. Potential value of nonechoplanar diffusionweighted. These changes are then tuned in conjunction with the gradient system frequency response function. Data were fed to the computer and analyzed using ibm spss software.
In this case, each rf excitation is followed by a train of gradient echoes with different spatial encoding. Te values as short as 12 msec can be achieved by using the faster and more powerful gradients required for echoplanar imaging. Dwi of the bone was performed in 32 patients with an echoplanar imaging epibased sequence followed by a noncpmg ssfse technique. Readoutsegmented echoplanar imaging improves the diagnostic performance of diffusionweighted mr breast examinations at 3. The echo planner imageepi was created as the fastest way of collecting data for k space. Diagnostic accuracy of nonechoplanar diffusionweighted. For non spin echo scans it is possible to calculate the ernst angle, a, at which the signal will be maximal for any combination of tr and t1 33 since the ordinary functional imaging application is to acquire a series of epi scans at a non infinite tr, the gradient echo methods can confer a slight signal advantage over spin echo studies. All statistical analyses were performed using spss16. Diagnostic accuracy of nonechoplanar diffusionweighted mri. This has the advantage of speed but suffers from susceptibility artifactsdistortions, low signaltonoise, and spatial blurring.
As shown on figures 1a to 1e, at ct, the patient with postmastoidectomy residual cholesteatoma presents a mass with soft tissue density obstructing the surgical cavity which, at magnetic resonance imaging mri, demonstrated diffusion restriction at non echoplanar imaging. These strong bmodulations may not impede diffusivity measurements based. Nonechoplanar diffusionweighted magnetic resonance imaging is superior to routine echoplanar diffusionweighted magnetic resonance imaging as it minimises susceptibility artefacts. Nonechoplanar diffusion weighted imaging in the detection. The epi sequence can be collected as a blipped or non blipped technique. Diffusion is also known as brownian motion, named in honor of scottish botanist robert brown who first observed spontaneous vibration of pollen particles under the microscope in 1827. Multishot readout segmented echo planar imaging rsepi and echo planar imaging with reduced fieldofview rfovepi are new, revolutionary techniques for obtaining highquality, distortionminimized diffusion weighted images of challenging body regions, such as the head and neck area, in clinically acceptable acquisition times fig. Echo planar imaging epi is certainly such a sequence.
Diffusionweighted mri in prostate cancer current research. The resolve sequence permits acquisition of multishot diffusion weighted echoplanar scans. Echoplanar imaging epi questions and answers in mri. Evaluating the utility of nonechoplanar diffusionweighted imaging in the preoperative evaluation of cholesteatoma.
Multiplexed echo planar imaging for subsecond whole brain. Echo planar imaging epi echo planar imaging sequences including. Nonepi dwi is a promising alternative to secondlook surgery for the. Singleshot echo planar imaging ssepi dwi is the current clinical standard due to its resistance to phase errors resulting from patient motion. Mar 01, 2014 this video describes the epi, the fastest technique in mri pulse sequence.
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