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CHAPTER SIX MRI CLINICAL APPLICATIONS

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6 CLINICAL APPLICATIONS

The clinical use of MRI has increased dramatically in the past decade and scanners maynow be found in all major UK hospitals and a growing number of regional ones. Theinstallation of a new scanner is a major capital expense but the provision of governmentassistance and the growing number of private finance initiatives (PFI) has brought the

acquisition of an MRI scanner within the reach of most NHS trusts. As technology improvesand more research is carried out, the range of clinical applications of MRI has expanded.This chapter presents some clinical investigations that I observed during my MRI training atNinewells Hospital.

1 Introduction

In clinical MRI, contrast in the image is governed by the fundamental tissue relaxationparameters T1 and T2, and the corresponding proton density. Varying these parameters ona case-by-case basis provides good soft tissue contrast and facilitates reliable diagnosis. Inthe clinical setting, T1 weighted images generally highlight the anatomy and T2 weighted

images generally highlight pathology 1. Contrast allows for the distinction among soft tissuetypes and it is the result of differences in tissue signal intensities. There are many factorsthat affect image contrast and these are highlighted in Table 1 below 2. In general, T1weighted images are characterised by bright fat and dark free water and T2 weightedimages by dark fat and bright free water. Air produces no MR signal and will appear darkin both cases.

2 Clinical Investigations

During my training I observed various MRI procedures performed by radiographers. Thesescans were carried out on both the Siemens Impact (1.0T) and Symphony (1.5T) scanners

during normal scanning hours.The following sections describe some examples of MRI examinations I observed during myMRI training along with the appropriate MRI Physics sequences. I have presented casestudies covering musculoskeletal MRI (knee), MR angiography (renal arteries), Neuro MRI(brain), Neuro MRI (spinal cord), body MRI (breast) and finally body MRI (liver). Thesestudies used basic T1W, T2W and PDW spin echo and turbo spin echo sequences as wellas inversion recovery sequences (STIR and FLAIR) and gradient echo sequences(predominantly FLASH and DESS). Many of these sequences involved the use of contrastagents or fat suppression techniques to improve the contrast and dynamic range of theresulting images. These methods are all described where appropriate, and the reason foruse in each case is discussed.

1 Musculoskeletal MRI (Knee)

A 40-year-old male patient presented with severe knee pain and trauma. The firstsequence used was a fat suppressed dual-echo turbo spin echo, with a TR 4000ms andtwo TEs of 22ms for PDW and 90 ms for T2W. The advantage of the dual echo sequenceis that proton density weighted images and T2 weighted images can be acquired from thesame RF excitation pulse, giving twice the amount of image information for the same scantime. In addition, the use of a turbo factor (in this case 5) reduces the scan time further andallows the data to be acquired in just a few minutes despite the long TR. Fat suppression

ensures that fluid signal is clearly visible, and will highlight pathology such as bone bruising.In this study, the extremity (knee) coil was used in transmit and receive mode, with thepatient in a supine position and feet first in the Siemens Symphony scanner. Figure 6-1


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below shows a coronal fat-suppressed T2W image from the dual echo data. The highsignal area to the left is indicative of severe joint effusion, which appears to be associatedwith extensive damage to the lateral meniscus.

Figure 6- 1: 2D Coronal Fat Suppressed T2W Knee Image from Dual Echo TSE Sequence(TR=4000ms, TE=22/90ms, FA=180, SL=3mm, NoS=19, FoV=179cm, RFoV=7/8,Matrix=225x512, Scan Time=64, AC=2, Turbo=5, SequenceName=tse5_22rrb130_90rrb130, FATSAT)

Figure 6-2 below shows sagittal images acquired using the PD_T2 dual echo turbo spinecho sequence. A large popliteal cyst is evident, which is more clearly visible on the T2W

image.

Figure 6- 2: 2D Sagittal Knee Images Obtained Using (L) PDW and (R) T2W Dual EchoTSE Sequence (TR=3000ms, TE=14/85ms, FA=180, SL=4mm, NoS=19, FoV=179cm,RFoV=7/8, Matrix=225x512, Scan Time=433, AC=2, Turbo=5, Sequence

Name=tse5_14b130_85b130, no FATSAT)

The cyst is probably fluid filled, and is contrasted very well on the T2W data relative to the


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surrounding muscle which is more hypointense. The cyst is also evident on the PDWimage, and this is most likely because the content of the cyst has a larger proton densitythan the surrounding muscle tissue.

A dual echo steady state (DESS) sequence was also used in addition to the dual echoturbo spin echo sequence. The DESS sequence provides rather complex image contrast,

which is roughly equivalent to T2 weighting. The DESS sequence is effectively a combinedFISP and PSIF sequence, where the FID signal from the FISP and the echo signal from thePSIF are added together. This improves the signal to noise ratio of the final image. TheDESS sequence (TR 27ms, TE 9 ms, FA 40o) again clearly highlights the lateral soft tissueeffusion in figure 6-3 (left) and the popliteal cyst figure 6-3 (right) below.

Figure 6- 3: 3D DESS Sequence showing (L) Lateral Soft Tissue Effusion and (R) PoplitealCyst (TR=27ms, TE=9ms, FA=40, SL=1.5mm, NoS=64, FoV=149cm, RFoV=7/8,Matrix=192x512, Scan Time=534, AC=1, Sequence Name=de3d_9b130, no FATSAT)

Finally, an inversion recovery (STIR) sequence was implemented to search in more detailfor marrow oedema as shown by figure 6-4 below. The image does not appear to showmarrow oedema but again clearly highlights the soft tissue swelling on the lateral side of theknee.


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Figure 6- 4: STIR Sequence. No Marrow Oedema but Clear Swelling on Lateral Side ofKnee (TR=6091ms, TE=30ms, TI=150ms, FA=90, SL=4mm, NoS=23, FoV=179cm,

RFoV=7/8, Matrix=378x512, Scan Time=535, AC=1, Turbo=7, SequenceName=tirm7_30b130, STIR FATSAT)This confirms that the soft tissue swelling is almost certainly fluid filled, since fatsuppression does not appear to affect the area. This could be further confirmed by runninga FLAIR sequence to suppress the fluid, although this was not implemented in thisparticular study.The Radiologists report highlighted the several features derived from the MR images of theabove examination. Knee effusion and popliteal cyst is present, deficiency of the anteriorcruciate ligament, tears to both horns of the lateral meniscus, and small parameniscal cystand finally a vertical tear to the posterior horn of the medial meniscus

2 MR Angiography (Renal Arteries)

There are three main methods of obtaining images of the human vasculature using MRI.These MR angiographic techniques are known as time-of-flight (TOF) MRA, phase contrast(PC) MRA and contrast-enhanced (CE) MRA.

1 Time-Of-Flight MRA

TOF MRA utilises the principle of in-flow enhancement as illustrated in chapter 9, slide 6(artefacts lecture). This method uses a T1W gradient echo sequence where the initial RFpulse saturates the blood within the slice. At the time the data is acquired however, theoriginal blood within the slice would have left the slice and been replaced by fresh bloodthat did not experience the initial RF pulse. Consequently the new blood protons wouldappear to have fully recovered to longitudinal equilibrium, relative to the surroundingstationary tissue protons within the slice. TOF MRA is still used routinely for imaging thecranial arteries around the Circle of Willis.

2 Phase Contrast MRA

Phase contrast (PC) methods use a different technique to generate vascular contrast,based on phase shifts of the flowing blood. Following the initial 90 pulse, bipolar gradients

are applied separately along the three axes to induce phase shifts to moving protons.Protons in stationary tissues acquire no net phase change as a result of the bipolar gradientpulses, but flowing protons within vessels accumulate phase as they move. For the next


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RF pulse, the polarity of the bipolar gradient is inverted, and a subtraction technique caneliminate the stationary background signal, to leave the moving blood clearly visible. Animportant variable in PC MRA is the velocity-encoding (VENC) factor, which can becontrolled to highlight arteries or veins. Higher VENC factors (e.g. 60-80 cm/sec) willselectively image the arteries, whereas slower VENC values (e.g. 20 cm/sec) will highlightthe venous system. The phase images from the PC MRA sequence can be displayed to

show direction of flow and to quantify these flow velocities within a vessel 2.

3 Contrast Enhanced MRA

Contrast enhanced MRA is most widely used method of MRA in clinical MRI. The use of agadolinium based contrast agent significantly reduces the T1 of the blood as the bolus ofcontrast agent passes through the vessels and a fast T1 weighted gradient echo sequenceprovides well defined, hyperintense vessels, provided that the images are acquired at theappropriate time. The technique works by subtraction of post-contrast images from apre-contrast baseline image. This will be described in more detail using the following caseof renal CE-MRA as an example.

4 CE-MRA Examination

A female patient aged 74 was referred for a CE-MRA examination on the basis ofhypertension and suspected cardiovascular disease. The examination consisted of fourphases, namely the planning phase, the bolus-timing phase, the CE-MRA phase and thedata analysis phase. The body phased array RF coil was selected for the examination. Thecoil was positioned on the patient, and an appropriate vein in the arm of the patient wasidentified for contrast injection. The patient was positioned supine and head first into theSiemens Symphony scanner. The first phase of the study was implemented to ensure thatthe appropriate slice orientation for CE-MRA was selected. Scout images were obtained

(with the patient in breath hold) using the TruFisp sequence (TR 6ms, TE 3ms, 4mm slicethicknesses). An example of a sagittal TruFisp image is shown in figure 6-5 below.

Figure 6- 5: 2D Sagittal TruFisp image of Abdomen (TR=6ms, TE=3ms, FA=70, SL=4mm,NoS=11, FoV=458cm, RFoV=8/8, Matrix=256x256, Scan Time=8 to 17, AC=1, SequenceName=trufi_3b560, No FATSAT)

From this dataset and the other orientations acquired, the correct imaging plane (runningparallel and through the descending aorta) for coronal oblique CE-MRA was identified. Theappropriate positioning of the coronal oblique slices is shown in dotted line in figure 6-5


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above.

Once the appropriate planning had been completed, a bolus timing experiment wasundertaken. This was achieved by delivering a 2ml test bolus of gadolinium contrast agent(Prohance, Bracco Inc), and then immediately acquiring back-to-back axial 3D volumeinterpolated breathold examination (VIBE) datasets with a temporal resolution of just under

seven seconds (see figure 6-6 A-C below).

AB

CFigure 6- 6: (A C) 3D (VIBE) Datasets With Temporal Resolution approx. 7s (TR=4.2ms,TE=1.9ms, FA=40, SL=3.1mm, NoS=32, FoV=498cm, RFoV=8/8, Matrix=256x256, ScanTime=6.8, AC=1, Sequence Name=fl3db_80m_2b488, FATSAT)

The approximate time taken for the contrast agent to reach the renal arteries wascalculated using this method. The advantage of using this method is that it is also possible

to obtain an assessment of the perfusion of the contrast agent through the renal arteriesand into the renal cortex 3.


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After the delay time for CE-MRA had been calculated from the VIBE timing experiments,the third phase, CE-MRA was implemented. The radiographers acquired a baseline coronaloblique 3D dataset (with slices less than 1.5mm thick) using a FLASH sequence with fatsuppression prior to contrast agent delivery. The contrast agent was then delivered as an18ml bolus with 20ml saline flush into the vein in the arm, and a delay time equivalent tothat calculated from the VIBE timing experiment was implemented, prior to the next 3D

coronal oblique (arterial phase) FLASH sequence. Finally, a third coronal oblique (venousphase) FLASH sequence was acquired in order to highlight the kidneys more clearly for thepurposes of kidney length and volume measurements (see chapter 8). An example of apre-contrast FLASH image, together with arterial phase post-contrast image and subtracteddataset can be observed in figures 6-7 A C below.

AB

C

Figure 6- 7: (A-C) Examples of a Pre-Contrast Coronal 3D FLASH image, Arterial PhasePost-Contrast and Subtracted Dataset (TR=4.6ms, TE=1.8ms, FA=25, SL=1.4mm,NoS=56, FoV=419cm, RFoV=8/8, Matrix=512x512, Scan Time=up to 18, AC=1, Sequence


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Name=fl3d_itn_2b390, FATSAT)

The data analysis phase consisted of generating a set of maximum intensity projection(MIP) images. This was achieved by subtracting the arterial phase data from thepre-contrast data, and using the MIP software on the subtracted data. The MIP algorithm

provides a series of angular projections through the subtracted 3D data, where the maximalsignal intensities are thresholded and highlighted. This allows the visualisation of the renalarteries more clearly through multiple planes. A diagnosis of renal artery stenoses was thenmade by a radiologist who classified the thinning of the arteries as minimal (0-30%occlusion), moderate (30-60% occlusion) or severe (70-100% occlusion).The highlighted example in figure 6-8 below shows a patient with tortuous vessels supplyingboth kidneys. However, the lumen of the right renal artery appears normal, whilst the leftrenal artery lumen is severely thinned and may require intervention by angioplasty or stentplacement.

Figure 6- 8: Outcome of CE-MRA Shows Tortuous Vessels Supplying Both Kidneys

3 Neuro MRI (Brain)

A 61-year-old male was referred for an MRI examination with a history of complex visualand vocal problems. The patients head was positioned in a transmit-and-receive

quadrature RF head coil, and the coil was subsequently centred into the magnet (SiemensSymphony scanner). The first sequence used was the dual echo turbo spin echosequence, where PDW and T2W axial slices of the entire brain were acquired as shown infigure 6-9 below.


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Figure 6- 9: 2D Dual Echo TSE Sequence Showing (L) PDW and (R) T2W Axial Slices ofBrain (TR=3000ms, TE=119/17ms, FA=180, SL=5mm, NoS=20, FoV=250cm, RFoV=6/8,Matrix=200x256, Scan Time=4 3, AC=2, Sequence Name=tse5_17b130_119b130, NoFATSAT)

There is some evidence of proton density change on the left side of the brain, but the lesionareas are much more clearly visible on the T2 weighted image (figure 6-9 right). A standardT1W multi-slice spin echo sequence was acquired in the sagittal orientation shown in figure6-10 below, but the lesions were quite difficult to spot on this image.

Figure 6- 10: 2D T1W Multi-Slice Spin Echo Sequence Showing Sagittal Brain (TR=525ms,TE=15ms, FA=90, SL=5mm, NoS=19, FoV=250cm, RFoV=6/8, Matrix=192x256, ScanTime=3 25, AC=1, Sequence Name=se15b130, No FATSAT)

Finally, an axial turbo FLAIR sequence was implemented with TR 9000ms, TE 110ms andTI 2500ms. These data highlight the lesion areas as hyperintense relative to the rest of the


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brain tissue as seen in figure 6-11 below.

Figure 6- 11: 2D FLAIR Sequence Showing Lesions Hyperintense Relative to Normal Brain(TR=9000ms, TE=110ms, TI=2500, FA=180, SL=5mm, NoS=19, FoV=250cm, RFoV=6/8,Matrix=176x256, Scan Time=2 33, AC=1, Sequence Name=tirm11_ild_100b195, NoFATSAT)

The appearance of hyperintense lesions on T2W and FLAIR images may be suggestive ofan internal bleed, together with the presence of fluid and blood by-products (such ashaemosiderin). If one compares the T2W turbo spin echo and the FLAIR images, smallcentral lesions can be seen that are hyperintense on the T2W image and hypointense onthe FLAIR image. These lesions are possibly fluid filled - with a T1 equivalent to CSF(since the chosen TI in the FLAIR acquisition should eliminate the signal from CSF).The radiologists report highlighted the following features derived from the MR images ofthe above examination. There was evidence of previous infarction within the left posteriorcerebral artery territory, (this includes the visual cortex). Also there appears to be ischemicchange within both middle cerebral arterial territories

4 Neuro MRI (Spinal Cord)

In this example, a 20 year-old female was referred for MRI for a brain and spinal scan forsuspected MS plaques. The cervical spine was initially scanned with the patient supine andhead first in the scanner (Siemens Symphony). T1W spin echo and T2W turbo spin echo

sequences were both used in the sagittal orientation, with the neck coil, and appropriatelyselected spine coil elements. The resulting images showed little information on the T1Wdata as shown in figure 6-12 (left) below, but areas of hyperintense signal in the spinal cordon the T2W data in figure 6-12 (right).


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Figure 6- 12: TSE Sequences Showing Sagittal Spine: (L) 2D T1W SE (TR=501ms,TE=15ms, FA=90, SL=3mm, NoS=13, FoV=280cm, RFoV=6/8, Matrix=224x512, ScanTime=5 39, AC=3, Sequence Name=se_15b130, No FATSAT) and (R) T2W TSE(TR=5000ms, TE=112ms, FA=180, SL=3mm, NoS=14, FoV=279cm, RFoV=6/8,Matrix=279x279, Scan Time=4 50, AC=3, Turbo=15, Sequence Name=tse15_112b130,No FATSAT)An axial MEDIC sequence was then implemented in the region of the signal change on thec-spine, derived from figure 6-12. A MEDIC sequence (multiple echo data imagecombination) was used instead of a T2 weighted sequence in this case because the MEDICsequence contains flow compensation gradients that remove CSF flow artefacts. Thesequence is basically a gradient echo sequence with multiple echo acquisitions resultingfrom reversed read out gradients. The multiple echoes are then superimposed onto the firstimage with the shortest echo time, which results in a predominantly T2 weighted final

image. In this case, an axial slice at the level of one of the high-signal lesions can be seenin figure 6-13 below.

Figure 6- 13: (L) Axial MEDIC Sequence Shows Predominantly T2W Image (TR=775ms,TE=27ms, FA=30, SL=3mm, NoS=15, FoV=229cm, RFoV=6/8, Matrix=192x256, ScanTime=4 59, AC=2, Sequence Name=me2d_6u_27b195, No FATSAT) and (R) 2D SagittalFLAIR sequence eliminates CSF signal (TR=9000ms, TE=110ms, TI=2500, FA=180,SL=3mm, NoS=13, FoV=300cm, RFoV=6/8, Matrix=352x512, Scan Time=4 39, AC=1,


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Turbo=11, Sequence Name=tirm11_ild_110b195, WATER SAT)Again, this shows an area of high signal within the spinal cord. Finally a sagittal FLAIRsequence was run, with inversion time TI = 2500 ms to eliminate the CSF signal. It can beseen in this case that the lesion is hyperintense relative to the rest of the spinal cord, whichwould be consistent with the suspected demyelinating disease that is suspected.The radiologists report highlighted the following features derived from the MR images of

the above examination. A small plaque is visible at C1 and a larger one at C3. Axial imagesconfirm the position of the plaques and demyelination is suspected.

5 Body MRI (Breast)

To demonstrate how MRI is used for breast imaging, data obtained from a female patient(aged 41) who was scanned for suspected recurrence of metastatic disease in the leftbreast was observed. The patient was positioned prone with both breasts enclosed by thebreast RF coil, and imaging was performed on the 1T Siemens Impact scanner. A coronalhigh-resolution 3D T1W gradient echo sequence (FLASH) was used to acquire thin slicesthrough the breasts, and a T2W spin echo sequence with fat saturation was also

implemented. Neither the high resolution T1W images nor the fat-suppressed T2W imagesin figure 6-14 were able to provide any direct indication of recurring metastases, althoughboth sets of images did indicate that the normal anatomy of the left breast was somewhatdisrupted (it is interesting to compare the structural differences in the circled region of theleft breast with a similar symmetrical area on the right breast).

Figure 6- 14: (Top) Coronal 3D T1W GE Sequence (FLASH) (TR=14.2ms, TE=6.7ms,FA=35, SL=2.5mm, NoS=64, FoV=339cm, RFoV=4/8, Matrix=192x512, Scan Time=2 56,AC=1, Sequence Name=fl3d_7b150n3, No FATSAT) and (Bottom) Coronal 3D T2W SESequence with FATSAT (TR=9365ms, TE=90ms, FA=180, SL=2mm, NoS=13,FoV=339cm, RFoV=4/8, Matrix=98x256, Scan Time=4 31, AC=1, SequenceName=tse7_90rrb130, FATSAT)

In order to further characterise this suspicious region of the left breast, a dynamic contrastenhanced T1W study was performed. The T1W study consisted of 3D T1W coronal

gradient echo FLASH images through the breasts. The sequence parameters were TR14ms, TE 7ms, with 2.5mm thick slices being acquired over a 340cm field of view. Theimaging time was just over 1min 30 seconds for each sequence. Two pre-contrast datasets


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were acquired (figures 6-15 a and b), and then 20ml of contrast agent (Prohance, BraccoInc) followed by a saline flush was delivered into a vein in the arm. Immediately followingcontrast agent injection, a series of five post-contrast FLASH datasets were acquired (oneafter another figures 6-15 c-f) each with a scan time of just over 1min 30 seconds.

Figure 6- 15: Dynamic Contrast Enhanced 3D T1W Study (TR=14ms, TE=7ms, FA=35,SL=2.5mm, NoS=64, FoV=340cm, RFoV=4/8, Matrix=98x256, Scan Time=1 29, AC=1,Sequence Name=fl3d_7b150, No FATSAT)

Regions of interest were then placed over the suspicious region (circled) where the contrastagent was taken up (see example subtracted dataset in figure 6-16 below), along with anarea of suspected healthy breast tissue.

Figure 6- 16: Subtracted Dataset

This analysis was performed for each dataset that was acquired. Plots of signal intensityversus scan number (= time) yielded contrast uptake curves (figure 6-17) for suspectedlesion area and healthy breast tissue.


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Figure 6- 17: Contrast Uptake Curves for Suspected Lesion Area and Healthy BreastTissue

The rapid uptake of contrast agent in the suspicious lesion, followed by gradual washoutover the period of the study suggested that the lesion was malignant. Had the contrastuptake been slower and steadier over the period of this study, with no washout period thenthis would have indicated the presence of a benign lesion. The radiologists reportconfirmed that the lesion was indicative of metastatic disease on the basis of these MRIfindings.

6 Body MRI (Liver)

Liver imaging was observed on two patients, who both had suspected liver lesions. Thepatients were referred for MRI in the hope that it would be possible to identify the natureand extent of these lesions. Imaging was performed with each patient supine on theSiemens Symphony scanner, and the body array coil was used in combination withselected elements from the spine coil. All sequences chosen provided axial breath holdimages, so scan times were restricted to 20 seconds or less.

The specific sequence parameters are shown below:

1. T1W GE (2D FLASH) - TR=102ms, TE=4.5ms, FA=70, SL=6mm, NoS=13,FoV=398cm, RFoV=6/8, Matrix=512x512, Scan Time=20, AC=1, SequenceName=fl2d_4b260, No FATSAT).

2. T2W 2D HASTE - TR=1100ms, TE=120ms, FA=150, SL=6mm, NoS=12, FoV=398cm,RFoV=6/8, Matrix=512x512, Scan Time=15, AC=1, Sequence Name=haste_60b488,FATSAT).

3. T2W 2D STIR - TR=4311ms, TE=66ms, FA=160, SL=6mm, NoS=12, FoV=398cm,

RFoV=6/8, Matrix=512x512, Scan Time=21, AC=1, Turbo=33, SequenceName=tirm33_78b325, STIR FATSAT).


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4. T1W 2D GE QFS (Quick FATSAT) - TR=148ms, TE=2.3ms, FA=70, SL=6mm,NoS=22, FoV=369cm, RFoV=6/8, Matrix=512x512, Scan Time=20, AC=1, SequenceName=fl2d_qfs_2b488, FATSAT).

A T1W gradient echo sequence was run for each patient (see figures 6-19 and 6-20 images1a and 1b), and the lesion appeared as hypointense relative to the rest of the liver

(indicating that the lesion probably has a longer T1 than the liver in each case).

Figure 6- 18: FLASH, HASTE, FATSAT and STIR Images of Suspected Liver LesionA T2W HASTE sequence (HASTE = Half Acquisition Turbo Spin Echo) and T2W STIR both

highlighted the lesions as hyperintense for both patients (see figures 6-19 and 6-20 images2a, 2b, 3a, 3b).

Figure 6- 19: FLASH, HASTE, FATSAT and STIR Images of Suspected Liver Lesion


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This indicates that each lesion probably has a longer T2 than the liver in both cases. AHASTE sequence is basically a fast version of a Turbo Spin Echo sequence, where justover half of k-space is acquired in the same way as a Turbo Spin Echo sequence, and theother half of k-space is synthesised (based on the first half of the acquisition). This ensuresthat HASTE is ideal for heavily T2 weighted breath hold examinations, and is ideal for casessuch as body imaging.

Finally a fast T1W gradient echo FLASH sequence was implemented before and afteradministration of a bolus of contrast agent (figures 6-19, 6-20 and 6-21 images 4a, 4b, 5a,5b).

Figure 6- 20: Post Gadolinium T1W EnhancementThe pre-contrast images provided essentially the same data as (images 1a and 1b), but the

post-contrast data showed different enhancement patterns. The lesion for the first patientdemonstrated rim enhancement, whilst the lesion for the second patient demonstratedcomplete enhancement. These differences in enhancement patterns provide additionalconfidence by which it is possible to diagnose the nature of the lesion. Post-contrast rimenhancement is often indicative of a metastatic lesion, whilst complete enhancement isoften indicative of a haemangioma. The radiologists final report confirmed these suspicionson the basis of these MRI investigations.

3 Conclusion on Clinical Applications

The time I spent shadowing radiographers in the MRI suite at Ninewells Hospitals was

immensely beneficial to me. It enabled me to better understand the various sequencesused and why they were used in particular cases.This chapter has presented a range of case studies I was able to observe, coveringmusculoskeletal MRI (knee), MR angiography (renal arteries), Neuro MRI (brain), NeuroMRI (spinal cord), body MRI (breast) and body MRI (liver). The cases presented here usedbasic T1W, T2W and PDW spin echo and turbo spin echo sequences as well as inversionrecovery sequences (STIR and FLAIR) and gradient echo sequences (predominantlyFLASH and DESS). Some of these sequences also involved the use of contrast agents orfat suppression techniques and these methods were all described and justified.

4 References

[1] Buxton R. B. Introduction to Functional Magnetic Resonance Imaging: Cambridge


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University Press, 2002: 126-128.[2] Houston J. G., Gandy S. J., Allen A., Dick J. B., Belch J. J., Stonebridge P. A. Spirallaminar flow in the abdominal aorta: A predictor of renal impairment deterioration in patientswith renal artery stenosis? Nephrology Dialysis Transplantation (2004 in press).[3] Sudarshan T., Gandy S., Armoogum K., Allan L., Sheppard D., Houston G.Measurement of Renal Cortical Perfusion in Patients with Renovascular Disease Using

MRI. Nephrol. Dial. Transplant. 2003; 18 (Suppl 4): W324.[4] McIntyre C. Magnetic Resonance Imaging Portfolio, 2001: 30-31.[5] Kim J. H., Kim M. J., Park S. I. et al. MR cholangiography in symptomatic gallstones:Diagnostic accuracy according to clinical risk group. Radiology 2002; 224:410-416.[6] Van Hoe L., Gryspeerdt S., Vanbeckevoort D. et al. Normal Vaterian sphinctercomplex: evaluation of morphology and contractility with dynamic single-shot MRcholangiopancreatography. AJR Am J Roentgenol 1998; 170:1497-1500.

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