Volume-rendered 3D display of MR angiograms in the diagnosis of cerebral arteriovenous malformations

Purpose: To determine whether application of a volume-rendered display of 3D time-of-flight (TOF) MR angiography could assist the diagnosis of cerebral arteriovenous malformations (AVMs).

Material and Methods: Volume-rendered 3D images of postcontrast 3D time-of-flight MR angiography were compared with conventional angiograms in 12 patients. The correlation between the 3D images and the operative findings was also analyzed in 5 patients.

Results: The 3D-displayed images showed all of the feeders and drainers in 10 and 9 patients, respectively. In all patients, the nidus was three-dimensionally visualized. In 3 patients with hematomas, the relationship between the hematoma and the AVM was well demonstrated. The 3D images corresponded well with the operative findings in the 5 patients.

Conclusion: This method is of help in assessing the relationship between the components of an AVM as well as that between an AVM and an associated hematoma.

[Mitral valve replacement for mitral regurgitation caused by papillary muscle head rupture complicating acute myocardial infarction: report of a case]

A 71-year-old female was admitted for acute posterolateral infarction. On the next day of the successful emergency perctaneous coronary intervention, she developed severe dyspnea and was intubated at intensive care unit. Massive mitral regurgitation was detected on color Doppler imaging and left ventricular cardiac failure was increasingly developed. The urgent operation was performed for papillary muscle rupture 18 days after first episode. Head rupture of the posterior papillary muscle was found during surgery and the mitral valve was replaced by a prosthetic valve (SJM # 25). The postoperative course was uneventful and she discharged on 52 days after surgery.

Volume-rendered 3D display of MR angiograms in the diagnosis of cerebral arteriovenous malformations

PURPOSE

To determine whether application of a volume-rendered display of 3D time-of-flight (TOF) MR angiography could assist the diagnosis of cerebral arteriovenous malformations (AVMs).

MATERIAL AND METHODS

Volume-rendered 3D images of postcontrast 3D time-of-flight MR angiography were compared with conventional angiograms in 12 patients. The correlation between the 3D images and the operative findings was also analyzed in 5 patients.

RESULTS

The 3D-displayed images showed all of the feeders and drainers in 10 and 9 patients, respectively. In all patients, the nidus was three-dimensionally visualized. In 3 patients with hematomas, the relationship between the hematoma and the AVM was well demonstrated. The 3D images corresponded well with the operative findings in the 5 patients.

CONCLUSION

This method is of help in assessing the relationship between the components of an AVM as well as that between an AVM and an associated hematoma.

Diffusion-weighted MRI of subdural and epidural empyemas

We reviewed diffusion-weighted images (DWI) from eight patients with subdural and four with epidural empyemas to assess the possibility of differentiating between these lesions by DWI. The signal intensities of the empyemas on DWI, and maps of the apparent diffusion coefficient (ADC) were analysed in seven patients. In seven of the eight patients with subdural empyema, the lesions appeared as areas of high signal. The ADC maps confirmed that these areas were the result of restricted diffusion. (In the remaining patient, the lesion showed a mixture of high and low signal.) The epidural empyemas contained areas of low signal in all four patients; part of the empyema was isointense or gave high signal in two. DWI may be an adjunct to conventional sequences for differentiating between subdural and epidural empyemas.

Diffusion-weighted MRI of the cervical spinal cord using a single-shot fast spin-echo technique: findings in normal subjects and in myelomalacia

We have implemented a new diffusion-weighted MRI (DWI) sequence based on the single-shot fast spin-echo technique. We hypothesised that this would add information to conventional MRI for diagnosis of lesions of the cervical spinal cord. DWI was performed using a technique in which echo collection after the application of motion-probing gradients was done in the same manner as in the single-shot fast spin-echo technique. We first imaged six healthy volunteers to demonstrate the cervical spinal cord using the sequence. Then we applied the sequence to 12 patients with cervical myelomalacia due to chronic cord compression. The spinal cord was well seen in all subjects without the distortion associated with echo-planar DWI. In the patients, lesions appeared as areas of low- or isointense signal on DWI. Calculated apparent diffusion coefficients of the lesions (3.30+/-0.38x10(-3) mm(2)/s) were significantly higher than those of normal volunteers (2.26+/-0.08x10(-3) mm(2)/s). Increased diffusion in areas of cervical myelomalacia, suggesting irreversible damage, can be detected using this technique.

Diffusion-weighted MR imaging of Carmofur-induced leukoencephalopathy

Carmofur (1-hexylcarbamyl-5-fluorouracil), a derivative of 5-fluorouracil (5-FU), has been widely used in Japan as a postoperative adjuvant chemotherapy agent for colorectal and breast cancer. Periventricular hyperintensity on T2-weighted MR images in carmofur-induced leukoencephalopathy confront the physician with a broad range of differential diagnoses. We describe two cases of carmofur-induced leukoencephalopathy in which diffusion-weighted MR imaging revealed periventricular hyperintensity. We compared their findings with those of age-related periventricular hyperintensity in five patients and found discrepancies in signal intensity of periventricular areas. Our results suggest that diffusion-weighted MR imaging may be useful to differentiate carmofur-induced leukoencephalopathy from age-related periventricular hyperintensity.

Duct-penetrating sign at MRCP: usefulness for differentiating inflammatory pancreatic mass from pancreatic carcinomas

PURPOSE

To define the duct-penetrating sign at magnetic resonance (MR) cholangiopancreatography (MRCP) and to assess the usefulness of this sign for distinguishing an inflammatory pancreatic mass (IPM) from a conventional pancreatic carcinoma (CPC) compared with arterial phase computed tomography (hereafter, CT) and arterial phase MR imaging (hereafter, MR imaging).

MATERIALS AND METHODS

MRCP, CT, and MR images were compared by means of receiver operating characteristic (ROC) analysis for 11 IPMs and 43 CPCs. With the MRCP images, a morphologic classification of the main pancreatic duct (MPD) was attempted for all lesions. On the basis of this classification and the enhancement patterns of a lesion, all readers graded the presence of IPM or CPC on a five-point scale for all images.

RESULTS

On the MRCP images, the morphologic characteristics of the MPD were nonobstruction for IPM (28 of 33, 85%) and obstruction or irregular stenosis for CPC (124 of 129, 96%). At ROC analysis among all the techniques, MRCP images had the highest value (0.98) for significant areas under the ROC curve (CT, 0.84; MR, 0.76) (P <.001). For the duct-penetrating sign in the broad sense (nonobstructed MPD) and the sign in the narrow sense (only normal MPD), the sensitivity, specificity, and accuracy for diagnosis of IPM were 85%, 96%, and 94%, respectively, and 36%, 100%, and 87%, respectively.

CONCLUSION

The duct-penetrating sign on MRCP images was more helpful to distinguish IPM from CPC than were the enhancement patterns on CT and MR images.

Non-contrast enhanced MR venography using 3D fresh blood imaging (FBI): initial experience

OBJECTIVE

This study examined the efficacy of 3D-fresh blood imaging (FBI) in patients with venous disease in the iliac region to lower extremity.

MATERIALS AND METHODS

Fourteen patients with venous disease were examined [8 deep venous thrombosis (DVT) and 6 varix] by 3D-FBI and 2D-TOF MRA. All FBI images and 2D-TOF images were evaluated in terms of visualization of the disease and compared with conventional X-ray venography (CV).

RESULTS

The total scan time of 3D-FBI ranged from 3 min 24 sec to 4 min 52 sec. 3D-FBI was positive in all 23 anatomical levels in which DVT was diagnosed by CV (100% sensitivity) as well as 2D-TOF. The delineation of collateral veins was superior or equal to that of 2D-TOF. 3D-FBI allowed depiction of varices in five of six cases; however, in one case, the evaluation was limited because the separation of arteries from veins was difficult.

CONCLUSION

The 3D-FBI technique, which allows iliac to peripheral MR venography without contrast medium within a short acquisition time, is considered clinically useful.

Quantitative evaluation of coronary stenosis by coronary magnetic resonance angiography

Coronary magnetic resonance angiography (coronary MRA) can detect, noninvasively, a high proportion of severe stenotic lesions found on coronary angiograms. However, quantitative evaluation of coronary artery stenosis by coronary MRA has been performed only in a small number of patients. This study was designed to determine whether coronary MRA can assess the degree of stenosis using the two-dimensional segmented turbo-FLASH method (2D method). We studied 108 patients with technically adequate coronary MRA images. The blood flow signal intensity on coronary MRA was classified as markedly decreased, moderately decreased, or normal. The severity of coronary artery stenosis was determined by the caliper method, and coronary stenosis was rated using a seven-point scale (0%, 25%, 50%, 75%, 90%, 99%, and 100%) in accordance with the American Heart Association classification system. Patients were classified into three groups: normal coronary artery (0%-25% stenosis), moderate stenosis (50%-75% stenosis), and severe stenosis (90%-100% stenosis). The degree of stenosis on coronary angiography and the decrease in coronary MRA signal intensity were compared. The right coronary artery was evaluated in 64 patients and the left coronary artery in 73 patients. When a marked or moderate decrease in coronary MRA blood flow signal intensity was defined as indicating stenosis, the sensitivity and specificity of coronary MRA for detecting angiographically severe stenosis were 85% and 80%, respectively. A moderate decrease in coronary MRA blood flow signal intensity detected angiographically moderate stenoses with a sensitivity of 38% and a specificity of 83%. Coronary MRA can detect a high proportion of severe stenoses but only a low proportion of moderate stenoses. Technical improvements are required before coronary MRA can be used clinically.

Preliminary evaluation of volume-rendered three-dimensional display of time-of-flight MR angiography in the diagnosis of intracranial aneurysms

We assessed the value of the volume-rendering method of displaying images of three-dimensional (3D) time-of-flight MR angiography (MRA) in the diagnosis of intracranial aneurysms. We obtained three-dimensional volume-rendered MRA from 21 patients with intracranial aneurysms. The images were evaluated in comparison with maximum-intensity-projection images (in 21 patients), conventional angiograms (in 21) and CT angiography (in nine). In 17 patients, 3D volume-rendered images were thought to show morphological features most clearly. They were superior to the other methods for demonstrating the precise location of the aneurysm in three patients and in showing the shape of the bleb in another three. 3D volume-rendered MRA can be effectively added to conventional imaging techniques for diagnosis of intracranial aneurysms.

FLAIR MR imaging for diagnosing intracranial meningeal carcinomatosis

OBJECTIVE

The purpose of this study was to compare unenhanced and contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging with other sequences to visualize meningeal carcinomatosis.

MATERIALS AND METHODS

Unenhanced FLAIR images were compared with spin echo T2-weighted and contrast-enhanced FLAIR images in five patients with documented meningeal carcinomatosis and four patients with suspected meningeal carcinomatosis. Comparisons were also made between contrast-enhanced T1-weighted and FLAIR images.

RESULTS

In six patients, the unenhanced FLAIR images showed areas of abnormal hyperintensity within the sulci that were not noted on the spin-echo T2-weighted images. In all patients, the contrast-enhanced FLAIR images also showed meningeal enhancement, periventricular enhancement, or both. The contrast-enhanced T1-weighted and FLAIR images were equivalent in their depiction of abnormal enhancement in five of the nine patients; contrast-enhanced FLAIR images were superior in three patients.

CONCLUSION

Unenhanced FLAIR images are of more value than spin-echo T2-weighted images for the diagnosis of intracranial meningeal carcinomatosis. Contrast-enhanced FLAIR images can sometimes surpass contrast-enhanced T1-weighted images in their quality.

Magnetic resonance cholangiopancreatography for diagnosing hepatolithiasis

BACKGROUND/AIMS

Direct cholangiography with endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography sometimes fails to adequately opacify the entire biliary tract, because of severe biliary obstruction caused by ductal stricture or lodged stones. We assessed the diagnostic accuracy of magnetic resonance cholangiopancreatography for hepatolithiasis.

METHODOLOGY

Five patients with hepatolithiasis underwent ultrasonography, computed tomography, direct cholangiography, and magnetic resonance cholangiopancreatography, using a half-Fourier acquisition single-shot turbo spin-echo sequence. Surgical exploration or pathologic examination revealed stricture and dilatation of the intrahepatic ducts in all patients. Diagnostic accuracies for stones and ductal abnormalities were compared among the imaging studies.

RESULTS

No complications occurred during magnetic resonance cholangiopancreatography studies. Magnetic resonance cholangiopancreatography fully depicted the biliary tract. Magnetic resonance cholangiopancreatography accurately detected and localized intrahepatic stones, as well as bile duct stricture and dilatation, in all patients. Intrahepatic stones were detected by endoscopic retrograde cholangiopancreatography in one of four patients and by percutaneous transhepatic cholangiography in all three who underwent this procedure. Endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography demonstrated ductal stricture in all patients but failed to completely demonstrate the biliary tree in three of four patients, and one of three, respectively. On ultrasonography and computed tomography, precise localization of stones was difficult. Ultrasonography and computed tomography failed to demonstrate ductal stricture in one and two of the five patients, respectively.

CONCLUSIONS

Magnetic resonance cholangiopancreatography diagnoses intrahepatic stones and bile duct abnormalities less invasively and more accurately than endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography.

Pre- and postcontrast FLAIR MR imaging in the diagnosis of intracranial meningeal pathology

PURPOSE

Few reports address the use of fluid-attenuated inversion-recovery (FLAIR) images of the brain in the diagnosis of extraaxial lesions. Our purpose was to assess the value of FLAIR images, including postcontrast ones, in the diagnosis of intracranial meningeal diseases.

METHODS

We reviewed precontrast (n=24) and postcontrast (n=20) FLAIR images obtained from 25 patients with infectious meningitis (n=13), carcinomatous meningitis or dissemination of primary brain tumor (n=7), dural metastasis (n=3), and others (n=2) in comparison with fast spin-echo T2-weighted and postcontrast T1-weighted images.

RESULTS

In lesion detectability, precontrast FLAIR images were significantly superior to fast spin-echo T2-weighted images but inferior to postcontrast T1-weighted images. There was no significant difference between postcontrast T1-weighted and FLAIR images.

CONCLUSION

Precontrast FLAIR images can substitute for conventional fast spin-echo T2-weighted images. Postcontrast FLAIR images have diagnostic potential equivalent to conventional postcontrast T1-weighted images.

MR digital subtraction angiography of cerebral arteriovenous malformations

BACKGROUND AND PURPOSE

Although phase-contrast MR angiography provides some information regarding hemodynamics of cerebral arteriovenous malformations (AVMs), most conventional MR angiographic techniques have not been helpful in this respect. We attempted to determine the value of MR digital subtraction angiography (DSA) in assessing AVM hemodynamics.

METHODS

We developed an MR DSA technique by combining rapid thick-section T1-weighted imaging with a bolus injection of contrast material. The temporal resolution was 0.56 to 0.61 seconds per scan. MR DSA images obtained from 14 patients with AVMs were reviewed. Anatomic depiction of each component of the AVM was rated using a four-point grading scale (excellent = 3, good = 2, fair = 1, poor = 0) to compare conventional vs MR angiograms.

RESULTS

We were able to obtain serial images in which passage of contrast material was evident within the AVM, although the sequence we used allowed images to be obtained in only one projection. The average score for feeders, nidi, and drainers was 1.6, 2.4, and 2.3, respectively, with an overall average of 2.1.

CONCLUSION

The spatial resolution of our technique may fall below the level needed for identification of small vascular components of an AVM. Additionally, the limited slab may restrict application of the technique to assessment of large or very small AVMs. MR DSA, however, can show the hemodynamics of AVMs and may serve as a supplement to conventional MR imaging in the diagnosis of cerebral AVMs.

MRI of influenza encephalopathy in children: value of diffusion-weighted imaging

PURPOSE

Our purpose was to describe the MR findings of influenza encephalopathy and assess the value of diffusion-weighted imaging for its diagnosis.

METHOD

We examined a total of five patients diagnosed as having influenza encephalopathy or encephalitis by MRI, including diffusion-weighted imaging. We analyzed the conventional images and compared them with diffusion-weighted images.

RESULTS

Abnormally hyperintense lesions of varying extent and location were noted on T2-weighted and fluid-attenuated inversion recovery images in the cortex and adjacent white matter in every case. They showed no contrast enhancement. Diffusion-weighted imaging demonstrated the lesions as areas of restricted proton diffusion more clearly than conventional imaging.

CONCLUSION

Influenza encephalopathy is depicted as areas of T2 elongation having a rather nonspecific distribution. Diffusion-weighted imaging can demonstrate the lesions sensitively and serve as a valuable adjunct to conventional MRI.

Cerebral perfusion MRI with arterial spin labeling technique at 0.5 Tesla

PURPOSE

Our aim was to evaluate the feasibility of cerebral perfusion MRI using an arterial spin labeling technique at 0.5 T.

METHOD

We performed perfusion imaging with a flow-sensitive alternating inversion recovery (FAIR) sequence in a total of 37 patients with cerebral infarction.

RESULTS

FAIR perfusion images demonstrated areas of pathological perfusion corresponding (13 patients) or not corresponding (15 patients) to the infarcted area on MR images. Among 19 patients in whom comparison between FAIR perfusion imaging and regional cerebral blood flow single photon emission CT was available, the two studies correlated well in 15 patients.

CONCLUSION

Our results indicate that the FAIR technique allows reliable cerebral perfusion imaging at 0.5 T.

Coronary MR angiography-a clinical experience in Japan

Magnetic resonance angiography (MRA) has been expected to provide a useful noninvasive means of assessing coronary artery disease as this disease continues to increase due to westernization of life style. Several Japanese investigators have assessed the diagnostic value of two-dimensional (2D) and 3D coronary MRA in clinical patients evaluated for ischemic heart disease. Almost all reports indicate a high correlation between findings on 2D MRA and findings on conventional coronary angiography (CAG) in patients with severe stenosis of proximal arteries. However, in our study involving 153 patients with ischemic heart disease, 2D MRA tended to underestimate lesions in patients with moderate stenotic lesions. Furthermore, this method could not be applied successfully in approximately 15% of our patients due to difficulty with breath-holding. These findings indicate some of the limitations associated with breath-holding in the 2D method. Recently, several reports have described high diagnostic accuracy using respiratory-gated 3D MRA with navigator echo. Effective use of a suitable contrast agent with better spatial and time resolution and better image reconstruction methods will enable 3D MRA to serve a useful role, even in screening for coronary artery disease. J. Magn. Reson. Imaging 1999;10:709-712.

Diffusion-weighted MR imaging of encephalitis

OBJECTIVE

Our purpose was to evaluate how well diffusion-weighted MR imaging shows viral or bacterial encephalitis in comparison with conventional MR imaging that includes T1- and T2-weighted spin-echo and fluid-attenuated inversion-recovery sequences.

CONCLUSION

In nine of the 13 patients examined, diffusion-weighted imaging was superior to other diagnostic imaging sequences (fluid-attenuated inversion-recovery sequences in eight patients and a T2-weighted spin-echo sequence in one patient). Diffusion-weighted imaging can serve as a method of detecting early encephalitic changes.

Diffusion-weighted MR imaging in multiple sclerosis: comparison with contrast-enhanced study

OBJECTIVE

To assess the utility of cerebral diffusion-weighted MR imaging in the diagnosis of multiple sclerosis (MS) in comparison with contrast-enhanced T1-weighted imaging.

METHODS AND MATERIALS

We reviewed T2-weighted spin-echo (SE), fluid-attenuated inversion-recovery (FLAIR), contrast-enhanced T1-weighted SE and echo-planar diffusion-weighted images (DWIs) obtained in seven patients with definite MS on nine occasions.

RESULTS

In total, 94 plaques were demonstrated on T2-weighted SE and/or FLAIR images. A total of 13 of these plaques showed enhancement on contrast-enhanced T1-weighted images and hyperintensity on DWIs, and five non-enhancing plaques showed hyperintensity on DWIs.

CONCLUSION

Diffusion-weighted imaging, which provides information based on pathophysiology different from contrast-enhanced imaging, is a potential supplementary technique for characterizing MS plaques.

Diffusion-weighted MR imaging with single-shot echo-planar imaging in the upper abdomen: preliminary clinical experience in 61 patients

BACKGROUND

To determine the potential ability of diffusion-weighted magnetic resonance (MR) imaging with single-shot echo-planar imaging (DW imaging) in the upper abdomen by apparent diffusion coefficient (ADC) and signal:intensity ratio (SIR) measurements.

METHODS

DW imaging was performed in 61 clinical patients. ADCs in the liver, pancreas, spleen, kidney, and different pathological conditions were calculated. Spleen-to-liver SIR and segmental intensity difference of the liver (SID) were also calculated.

RESULTS

The mean ADCs (mm(2)/s) were 2.28 x 10(-3) +/- 0.07 in the liver, 1.44 x 10(-3) +/- 0.05 in the spleen, 1.94 x 10(-3) +/- 0.19 in the pancreas, and 5.76 x 10(-3) +/- 0.06 in the kidney. The mean ADC of cirrhotic liver was 1.96 x 10(-3) +/- 0.62, which was lower than that of normal liver. Other pathologic conditions also showed ADCs different from those of normal tissues. All DW images showed significantly higher spleen-to-liver SIRs and SIDs than did T2-weighted images (p < 0.05).

CONCLUSION

The mean ADCs obtained with DW imaging were different in each upper abdominal organ and with each pathologic condition. DW images showed better soft tissue contrast than did T2-weighted images with regard to SIR and CNR in depicting and characterizing upper abdominal disorders.

Clinical application of single shot GRE-EPI as non-enhanced MRA (EPI-MRA) for aortic aneurysm and dissection

We investigated the usefulness of single shot gradient echo type echo planar imaging (GRE-EPI) as magnetic resonance angiography (MRA) for the diagnosis of aortic aneurysm and dissection. This technique can detect blood flow signals in several tenths of a milliseconds without the need for contrast medium, breath-holding, or electrocardiographic (ECG) gating. By scanning approximately 20 frames in the coronal plane, three-dimensional (3D) imaging can be achieved by maximum intensity projection (MIP) at different angles. Three radiologists evaluated the ability of this single shot GRE-EPI as non-enhanced MRA (EPI-MRA) to diagnose aortic aneurysm and dissection. The examined lesions consisted of three cases of thoracic aortic aneurysm, seven of abdominal aortic aneurysm and eight of aortic dissection with a total of 15 involved aorta. In all patients with aortic aneurysm, EPI enabled detection and diagnosis of the aneurysm. However, the size of the lesion and relationship with major branches were determined only in the abdominal aorta, and could not be determined precisely in thoracic lesions. Similar results were obtained for patients with aortic dissection. The technique visualized the intimal flap and enabled determination of the extent of dissection in the abdominal aorta. In the thoracic aorta, serious magnetic susceptibility artifacts caused image distortion, and as a result only the dissection could be detected and diagnosed. No entry site was detected at either the abdominal or thoracic aorta. These results suggest that EPI-MRA may have a clinical potential for screening patients with acute aortic disease who cannot undergo physical restraint for scanning.

MRI artifacts of metallic stents derived from imaging sequencing and the ferromagnetic nature of materials

In vitro and in vivo studies were performed to assess the optimum materials and imaging methods for metallic stents by conducting an in vitro investigation of MRI artifacts arising during imaging by several representative imaging methods using various types of stents and by clarifying the differences occurring with different metals and imaging sequences. We also examined the use of MRCP and MRA in evaluating luminal patency within stented biliary tracts and blood vessels in vivo. In vitro study showed either no artifacts or very slight artifacts created by titanium stents, however, marked image distortion was created by a stainless steel stent. Using SE instead of GRE sequences can minimize these artifacts. Echo planar imaging (EPI) produced severe susceptibility artifacts, resulting in unsatisfactory images. In vitro and in vivo studies indicated that MRCP was an effective method for follow-up studies of bile duct stents, but that MRA is quite limited as a method of follow-up study for currently available vascular stents.

Perfusion MR imaging with a superparamagnetic iron oxide using T2-weighted and susceptibility-sensitive echoplanar sequences: evaluation of tumor vascularity in hepatocellular carcinoma

OBJECTIVE

The study purpose was to examine the usefulness of perfusion echoplanar MR imaging with a superparamagnetic iron oxide (SHU-555A) for evaluating the vascularity of hepatocellular carcinomas.

SUBJECTS AND METHODS

Twenty-two patients with 32 hepatocellular carcinomas underwent perfusion imaging with bolus injection (0.7-1.1 ml) of SHU-555A. Echoplanar sequences included multishot spin-echo (17 patients) and single-shot gradient-echo (five patients) imaging. Image acquisition was repeated every 30 sec for 3 min with the multishot spin-echo sequence and every 2 sec for 100 sec with the single-shot gradient-echo sequence. Lesion signal intensity versus time curves were created for quantitative analysis.

RESULTS

Transient decreases in tumor signal intensity (28.8% with multishot spin-echo and 63.3% with the single-shot gradient-echo) were seen in the perfusion phase. These decreases in signal intensity were statistically significantly (p < .01) different for each histologic type of hepatocellular carcinoma (poorly differentiated, 43.3%; well differentiated, 18.4%; and moderately differentiated, 24.8%). After the perfusion phase, the tumor signal intensities rapidly recovered. The multishot spin-echo sequence could detect some signal changes even in lesions smaller than 1 cm.

CONCLUSION

Hepatocellular carcinoma vascularity can be evaluated with perfusion echoplanar imaging with SHU-555A. Because of its excellent temporal resolution, the single-shot gradient-echo echoplanar sequence detects the transient signal decrease in most lesions. The high image quality of the multishot spin-echo echoplanar sequence allows evaluation of the vascularity of even very small lesions.

A new MRI technique for demonstrating the surface of the brain together with the cortical veins

We assessed combining of surface-anatomy scanning (SAS) MRI and MR venography (MRV). We obtained SAS images with a half-Fourier single-shot fast spin-echo sequence, then MRV of the identical section with a two-dimensional phase-contrast technique. We then added the two sets of images. The combined images, which were obtained within 10 min, provided information about the surface anatomy and cortical veins. This simple technique is useful for demonstrating brain surface structures, especially in patients from whom one plans to excise a lesion.

A new technique of surface anatomy MR scanning of the brain: its application to scalp incision planning

BACKGROUND AND PURPOSE

Surface anatomy scanning (SAS) is an established technique for demonstrating the brain's surface. We describe our experience in applying SAS with superposition of MR venograms to preoperative scalp incision planning.

METHODS

In 16 patients, scalp incision planning was done by placing a water-filled plastic tube at the intended incision site when we performed SAS using half-Fourier single-shot fast spin-echo sequences. Two-dimensional phase-contrast MR angiograms were obtained to demonstrate the cortical veins and then superimposed upon the SAS images. The added images were compared with surgical findings using a four-point grading scale (0 to 3, poor to excellent).

RESULTS

In each case, neurosurgeons could easily reach the lesion. Surgical findings correlated well with MR angiogram-added SAS images, with an average score of 2.56.

CONCLUSION

Our simple technique is a useful means of preoperatively determining brain surface anatomy and can be used to plan a scalp incision site.

MR myelography of sacral meningeal cysts

PURPOSE

To describe the findings of sacral meningeal cysts (SMCs) on MR myelography and assess its value for the diagnosis of SMCs.

MATERIAL AND METHODS

We evaluated the MR images and MR myelograms obtained from 10 patients with SMC. MR myelograms were obtained using a 2D or 3D single-shot fast spin-echo sequence. In 5 patients, X-ray myelograms and postmyelographic CT images were compared with the MR myelograms.

RESULTS

A total of 33 SMCs were diagnosed within the spinal canal and/or sacral foramen. MR myelograms clearly revealed each cyst as a well-defined mass showing hyperintensity (10 cysts) or isointensity (23 cysts) compared to cerebrospinal fluid. MR myelograms demonstrated SMCs better than X-ray myelograms and postmyelographic CT images in 3 of the 5 patients.

CONCLUSION

MR myelography can be an adjunct to conventional imaging techniques when surgical treatment is indicated, because it can precisely delineate the extent of SMCs.

Fast dynamic MRI of aortic dissection: flow assessment by subsecondal imaging

PURPOSE

The aim of this study was to evaluate fast dynamic MRI, which consists of a subsecondal MRI sequence combined with a rapid contrast medium infusion technique, in examining clinical cases of aortic dissection.

MATERIALS AND METHODS

The subjects consisted of 27 patients with aortic dissection. Turbo-FLASH imaging of the aorta was conducted to obtain 50 image frames within 40 seconds.

RESULTS

Recognition of the intimal flap and differentiation of the true channel from the false channel was easily accomplished in all 15 patients with a patent false channel. The entry site was detected in 13 of 15 patients. Differentiation of slow flow from thrombus in the false channel was possible in all 27 cases, and the relationship between the lesion and the main branches of the aortic arch was identified in 26 of 27 cases.

CONCLUSION

Fast dynamic MRI may provide a large amount of information that is useful for the diagnosis of aortic dissection.

Combination of surface anatomy MRI and MR venography to demonstrate cerebral cortex and cortical veins on one image

We assessed in 12 patients the value of MR images in which a surface anatomy scanning (SAS) image and an MR venogram are added. We obtained SAS images using the half-Fourier technique and MR venograms with the 2D phase-contrast technique. The added images provided sufficient information concerning brain surface as well as cortical veins. Their findings correlated with those at surgery in six patients who underwent scalp incision marking. This technique provides valuable anatomical information preoperatively.

[The utilities and outlooks of MR cholangiography (MRCP) as a non contrast and noninvasive technique]

Endoscopic retrograde cholangiopancreatography (ERCP) is regarded as the diagnostic procedure of decision for abnormalities of the biliary and pancreatic ducts. However, ERCP is unsuccessful in 3-10% cases and is also associated with a 1-5% risk of producer-induced pancreatitis and other complications. MR cholangiography (MRCP) has recently developed as a noninvasive examination for evaluation of pancreaticobiliary diseases. Heavily T2-weighted fat-suppressed sequences are used to obtain these images. On MRCP, static fluid, such as bile or pancreatic juice represents hyperintense without injection of contrast medium. Therefore, MRCP could be examined in almost all patients including as infant or the patients of post reconstruction of gastrointestinal tract without any complication. In this paper, I described the several utilities and outlooks of MRCP as a noninvasive technique through the representative clinical applications.

[Common bile ductal carcinoma, hilar cholangiocarcinoma: evaluation with MR cholangiography]

Recently, imaging of bile ductal carcinoma has been improved by new techniques such as MR cholangiography. Cancer invasion along the bile duct has been demonstrated by MR cholangiography. MR cholangiography will be useful for obtaining more detailed information in the diagnosis and staging of common bile ductal carcinoma, hilar cholangiocarcinoma.

[Breath-hold MR cholangiopancreatography with 2D and 3D-FASE sequence at 0.5 tesla: evaluation based on measurements of signal intensity ratio and contrast-to-noise ratio]

Single-slice 2D-FASE (more than 2 cm) and 3D-FASE images proved to be reliable techniques by which to create high-resolution MRCP images at 0.5 T. In particular, 3D-FASE sequence can provided MIP and its thin source images with sufficient SIR and CNR of the images, which are useful to evaluate detailed structures. Using 3D-FASE sequence, even the non-dilated pancreatobiliary system can frequently be demonstrated because each source image retains satisfactory SIR and CNR of the images due to 3D acquisition and is not affected by motion artifacts of any kind. The most important problem for 3D-FASE sequence is that view-to view amplitude modulation errors may persist, though gradient moment errors can be reduced because of no actual motion during acquisition, resulting in degraded the MIP images due to the different positions of the source images in a few patients with inconstant respiration.

Magnetic resonance cholangiography using half-Fourier acquisition for diagnosing choledocholithiasis

OBJECTIVE

Magnetic resonance cholangiography (MRC), using a half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence, noninvasively provides very rapid (1-2 s) and high-quality images of the biliary tract. We assessed the diagnostic usefulness of HASTE-MRC for choledocholithiasis.

METHODS

A total of 101 patients with suspected choledocholithiasis underwent MRC, ultrasonography, and endoscopic retrograde cholangiopancreatography (ERCP). In 97 patients in whom ERCP fully depicted the common bile duct, we retrospectively analyzed the capability of MRC to image the common bile duct and to diagnose choledocholithiasis, in comparison with that of ultrasonography.

RESULTS

In 34 patients, ERCP demonstrated bile duct stones, which were confirmed at endoscopic or surgical treatment. The common bile duct was fully delineated in 98% by MRC and in 70% by ultrasonography. MRC (91%) was more sensitive than ultrasonography (71%) for detecting choledocholithiasis (p < 0.05). MRC demonstrated bile duct stones in all patients with stones > or =11 mm but missed calculi in the 29% of patients with small (3-5 mm) stones. MRC was capable of detecting choledocholithiasis regardless of bile duct caliber. The specificity of MRC (100%) was higher than that of ultrasonography (95%).

CONCLUSION

HASTE-MRC, a fast and noninvasive procedure, can accurately diagnose choledocholithiasis although the detectability for small stones is limited.

Diagnosis of anomalous pancreaticobiliary junction: value of magnetic resonance cholangiopancreatography

BACKGROUND

Anomalous pancreaticobiliary junction (a long common channel), with or without congenital choledochal cyst, is frequently associated with biliary tract carcinoma. We assessed the diagnostic value of magnetic resonance cholangiopancreatography (MRCP) for patients with anomalous pancreaticobiliary junction (PBJ).

METHODS

In 159 adult patients with pancreatobiliary disease, breath-hold (1 to 18 seconds) MRCP was performed according to a half-Fourier acquisition single-shot turbo spin-echo sequence. In all patients the length of the common channel demonstrated by MRCP was compared with that demonstrated by endoscopic retrograde cholangiopancreatography. In 11 patients with anomalous PBJ (the common channel > or = 15 mm on endoscopic retrograde cholangiopancreatography), the diagnostic accuracy of MRCP for associated biliary diseases was evaluated.

RESULTS

No complications were encountered in performing MRCP. On MRCP, the length of the common channel was calculated to be 15 mm or longer in nine (82%) of 11 patients with anomalous PBJ. In patients with normal PBJ, MRCP identified PBJ with the channel measuring 0 mm in length. MRCP allowed detailed visualization of congenital choledochal cyst (all seven patients) but failed to depict carcinoma (one patient) and mucosal hyperplasia (five patients) of the gallbladder.

CONCLUSIONS

MRCP is a noninvasive and accurate imaging method for diagnosing anomalous PBJ and congenital choledochal cyst.

MR cisternography using a three-dimensional half-fourier single-shot fast spin-echo sequence

Application of a three-dimensional half-fourier single-shot fast spin-echo sequence to MR cisternography is presented. This technique is capable of demonstrating normal cranial nerves. It is also useful in screening for acoustic neuroma as well as in the diagnosis of neurovascular compression.

Limb salvage and survival rates among elderly patients with advanced limb ischemia

The purpose of this study was to clarify the incidence of limb salvage and patient survival rates among elderly patients with advanced leg ischemia. We reviewed the records of 159 patients treated for advanced ischemia over a 15-year period at Aichi Medical University, 74 of whom were aged over 75 years and 85, between 65 and 74 years. There was a collective total of 186 limbs; 82 in the older group and 104 in the younger group. The older group had a greater proportion of women, and a higher incidence of coronary heart disease, pulmonary dysfunction, and acute onset of advanced ischemia than the younger group. Limb salvage was achieved in 73% of the affected limbs in the older group and in 92% of the limbs in the younger group. The poor limb salvage rate in the older group was mainly related to the high initial amputation rate. Early recognition of the sentinel ischemic signs before the ischemia is essential, especially in the elderly. Timely revascularization should be attempted whenever possible, and it should not be abandoned simply because the patient is deemed too old. The 1-, 3-, and 5-year survival rates in the older group were 59%, 28%, and 23%, respectively, which were markedly poorer than the expected survival rates of the age- and sex-matched Japanese population at 1, 3, and 5 years, which were 93%, 79%, and 65%, respectively. Thus, advanced limb ischemia carries a poor prognosis to the point of being life-threatening, and further continuous systemic management with the collaboration of physicians and surgeons must be provided even after the patient has left the hospital.

Diagnosis of anomalous pancreaticobiliary junction: value of magnetic resonance cholangiopancreatography

BACKGROUND

Anomalous pancreaticobiliary junction (a long common channel), with or without congenital choledochal cyst, is frequently associated with biliary tract carcinoma. We assessed the diagnostic value of magnetic resonance cholangiopancreatography (MRCP) for patients with anomalous pancreaticobiliary junction (PBJ).

METHODS

In 159 adult patients with pancreatobiliary disease, breath-hold (1 to 18 seconds) MRCP was performed according to a half-Fourier acquisition single-shot turbo spin-echo sequence. In all patients the length of the common channel demonstrated by MRCP was compared with that demonstrated by endoscopic retrograde cholangiopancreatography. In 11 patients with anomalous PBJ (the common channel > or = 15 mm on endoscopic retrograde cholangiopancreatography), the diagnostic accuracy of MRCP for associated biliary diseases was evaluated.

RESULTS

No complications were encountered in performing MRCP. On MRCP, the length of the common channel was calculated to be 15 mm or longer in nine (82%) of 11 patients with anomalous PBJ. In patients with normal PBJ, MRCP identified PBJ with the channel measuring 0 mm in length. MRCP allowed detailed visualization of congenital choledochal cyst (all seven patients) but failed to depict carcinoma (one patient) and mucosal hyperplasia (five patients) of the gallbladder.

CONCLUSIONS

MRCP is a noninvasive and accurate imaging method for diagnosing anomalous PBJ and congenital choledochal cyst.

Characterization of hepatic lesions by perfusion-weighted MR imaging with an echoplanar sequence

OBJECTIVE

The purpose of this study was to examine the usefulness of perfusion-weighted MR imaging with a single-shot gradient echoplanar sequence in characterizing hepatic tumors.

SUBJECTS AND METHODS

Perfusion-weighted imaging was performed in 61 patients with 91 confirmed hepatic tumors (14 hemangiomas, 19 metastases, and 58 hepatocellular carcinomas). The perfusion-weighted imaging was started at the time of administration of 0.1 mmol/kg of gadolinium, and images were continuously obtained every 2 sec for 88 sec. Time-intensity curves for all the tumors were created for quantitative analysis. Patterns of enhancement were also evaluated.

RESULTS

Changes in signal intensity that occurred throughout examination differed in three types of tumor. Transient signal intensity decreases in the perfusion phase significantly differed in three types of tumors (46% in hepatocellular carcinoma, 48% in hemangioma, and 15% in metastasis, p < .05 for hepatocellular carcinoma versus metastasis and for hemangioma versus metastasis). Signal intensity recovered rapidly for hepatocellular carcinoma and metastasis, whereas recovery was slower for hemangioma. Final signal intensity recovery was 94% in hepatocellular carcinoma, 91% in metastasis, and 54% in hemangioma compared with their initial signal intensities. (p < .05 for hepatocellular carcinoma versus hemangioma and for hemangioma versus metastasis.) The enhancement patterns also differed in three types of tumor.

CONCLUSION

Perfusion-weighted imaging with a gradient echoplanar sequence provides real-time mapping of many points along the enhancement profile curves because of its excellent temporal resolution. Therefore, it accurately characterizes hepatic tumors based on their different negative-enhancement patterns.

Improvement of MR cholangiopancreatography at .5 T: three-dimensional half-averaged single-shot fast spin echo with multi-breath-hold technique

The purpose of this study was to determine the advantage of a three-dimensional (3D) single-shot fast-spin-echo (SSFSE) sequence to obtain MR cholangiopancreatography (MRCP) with a .5-T MR unit by comparison with a two-dimensional (2D) SSFSE sequence. MRCP with 2D-SSFSE and with 3D-SSFSE with 128 echo train lengths was performed on 15 volunteers and 38 patients with pancreatobiliary disease using a .5-T MR unit. For maximum intensity projection (MIP) reconstruction, the section thickness of source images was 4 mm in the 2D-SSFSE and 3 mm in the 3D-SSFSE. 3D volume data in 3D-SSFSE were obtained using repeated short breath-hold of 2 seconds for every repetition time throughout the examination. The image quality, duct conspicuity, signal-intensity ratio (SIR), and contrast-to-noise ratio (CNR) were evaluated. In 23 of the patients who underwent both MRCP and direct cholangiopancreatography (endoscopic retrograde cholangiopancreatography [ERCP]/percutaneous transhepatic cholangiography [PTC]), a comparison between these two modalities was also conducted. The image quality of the MIP image with 3D-SSFSE (49 of 53, 92.5% graded excellent or good) was superior to that with 2D-SSFSE (31 of 53, 58.4%). Duct conspicuity, SIR, and CNR were significantly higher with 3D-SSFSE than with 2D-SSFSE. 3D-SSFSE also showed a stronger relationship with the ERCP/PTC findings compared to 2D-SSFSE. 3D-SSFSE provided satisfactory quality, SIR, and CNR of MRCP images, even when a .5-T MR unit was used, because the breath-hold technique used during 3D data sampling minimized all types of motion effects.

Intraductal papillary tumors of the pancreas: evaluation with magnetic resonance cholangiopancreatography

OBJECTIVE

We analyzed the findings of intraductal papillary tumors of the pancreas by magnetic resonance cholangiopancreatography (MRCP).

METHODS

Twelve patients with intraductal papillary tumors (main duct type, n = 3; branch duct type, n = 8; combined type, n = 1) underwent endoscopic retrograde cholangiopancreatography (ERCP) (n = 11) and MRCP, using half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences (n = 12). Imaging findings were compared with operative and pathological findings in all the patients.

RESULTS

Although ERCP failed to fully depict the main pancreatic duct and cystic tumors in six of 11 patients because of copious intraductal mucin, MRCP provided complete images of these structures in all 12 patients. In main duct type tumors, MRCP demonstrated moderate-marked, diffuse dilation of the main pancreatic duct. Branch duct type tumors showed "grape-like" clusters of cysts with no or only mild, diffuse dilation of the main duct. In combined type tumors, MRCP demonstrated a markedly dilated main duct with a large unilocular cyst of the collateral duct. MRCP detected more mural nodules (75%, three of four patients) than ERCP (25%, one of four). MRCP allowed more precise diagnosis of the type, size, and extent of tumors than ERCP, as confirmed by pathologic findings.

CONCLUSION

MRCP demonstrates intraductal papillary tumors less invasively and more completely than ERCP.

Diffusion-weighted MR imaging with a single-shot echoplanar sequence: detection and characterization of focal hepatic lesions

OBJECTIVE

The purpose of this study was to determine the usefulness of diffusion-weighted MR imaging with single-shot echoplanar imaging in characterizing focal hepatic lesions by apparent diffusion coefficient (ADC) and contrast-to-noise ratio (CNR) measurements.

MATERIALS AND METHODS

Diffusion-weighted imaging on a 1.5-T MR unit was performed in 46 patients with 74 known focal hepatic lesions (11 hemangiomas, 15 metastases, and 48 hepatocellular carcinomas [HCCs]). Mean values for ADCs and CNRs of all lesions were calculated. Mean values for CNRs with diffusion-weighted imaging were also compared with those for breath-hold T2-weighted fast spin-echo images.

RESULTS

The mean values for ADCs were different for each type of tumor (5.39 x 10(-3) mm2/sec +/- 1.23 in hemangiomas, 2.85 x 10(-3) mm2/sec +/- 0.59 in metastases, and 3.84 x 10(-3) mm2/sec +/- 0.92 in HCCs), and each of them was significantly greater than the mean values for ADCs of the normal liver (2.28 x 10(-3) mm2/sec +/- 1.23 in normal liver [p < .05] except metastasis versus normal liver [p < .1]). Also, the mean values for ADCs were based on differences of ADC values. Only four (6%) of 63 malignant tumors (three HCCs and one metastasis) could not be differentiated from hemangiomas. The mean value for CNRs with diffusion-weighted images (14.4 +/- 8.54 in HCC and 29.0 +/- 6.79 in metastasis) was significantly higher than the mean values for CNRs obtained with T2-weighted fast spin-echo images in both metastases and HCCs (p < .05), whereas no significant difference was seen for hemangiomas.

CONCLUSION

Mean values for ADCs differed for the three types of the hepatic lesions and were higher than ADCs of the normal liver. We suggest that diffusion-weighted imaging may be useful for increased detection of HCCs and metastases and in distinguishing these entities from hemangiomas.

Echo-planar perfusion MR of moyamoya disease

PURPOSE

Our goal was to assess the value of perfusion MR imaging by using a single-shot echo-planar technique to evaluate the hemodynamics of moyamoya disease.

METHODS

We performed echo-planar perfusion studies in 19 patients with a 1.5-T unit, using a free-induction-decay echo-planar sequence for 14 examinations and a turbo-gradient-spin-echo echo-planar sequence for five examinations. After a bolus injection of contrast material, 30 consecutive scans were done in 10 sections every 2 seconds. The data were analyzed to yield time-intensity curves for a region of interest set in the territory of the bilateral middle and/or anterior cerebral arteries in all examinations and to produce semiquantitative flow maps of each section, representing the signal decrease due to passage of contrast material in 17 examinations. The semiquantitative flow maps were compared with single-photon emission CT (SPECT) findings in 11 cases.

RESULTS

We detected differences between the cerebral hemispheres and/or focal perfusion abnormalities by the time-intensity curves and semiquantitative flow maps in 15 of the 19 examinations and in 11 of the 17 examinations, respectively. Results of one or both these examinations corresponded with the SPECT findings in nine of the 11 examinations.

CONCLUSION

Our results indicate that single-shot echo-planar perfusion MR imaging can sensitively depict hemodynamic abnormalities in moyamoya disease.

Perfusion-weighted MR imaging in the upper abdomen: preliminary clinical experience in 61 patients

OBJECTIVE

We quantitatively analyzed the potential usefulness of perfusion-weighted (PW) MR imaging of the upper abdomen performed with a single-shot gradient-recalled echo echoplanar (GRE EP) sequence.

SUBJECTS AND METHODS

PW imaging of the upper abdomen with a GRE EP sequence was performed in 61 patients who had suspected liver or pancreatic disease. PW imaging was started at the time of administration of 0.1 mmol/kg of gadopentetate dimeglumine, and images were obtained every 2 sec for 88 sec. Time-intensity curves for the liver, pancreas, spleen, and kidney, and for subgroups of patients with various pathologic conditions, were constructed for quantitative analysis.

RESULTS

The signal-intensity changes seen throughout the PW imaging process differed for each abdominal organ and pathologic condition. In the spleen, pancreas, and renal cortex, a transient signal-intensity decrease was seen in the perfusion phase (42%, 39%, and 78%, respectively). In the liver and renal medulla, the maximum signal-intensity decrease occurred in the later phase rather than in the perfusion phase. Signal-intensity recovery in the spleen and pancreas occurred soon after the maximum signal-intensity decrease, whereas such recovery was delayed in the liver and renal cortex. In cirrhotic livers, the signal-intensity change seen throughout the examination was minimal.

CONCLUSION

Unlike conventional MR imaging, PW imaging with a GRE EP sequence can provide detailed hemodynamic information about upper abdomen organs and about disorders of these organs because of its excellent temporal resolution and susceptibility to contrast enhancement.

Directed proximal magnetic resonance coronary angiography compared with conventional contrast coronary angiography

Magnetic resonance coronary angiography in 36 patients with proximal 1-vessel disease within 1 week of contrast coronary angiography was performed and the time required to complete the study was 13.4 +/- 4.2 min 13.2 +/- 8.1 minutes for the right and left coronary arteries, respectively. The sensitivity, specificity, positive and negative predictive values, and accuracy of magnetic resonance coronary angiography were 100% for right cronary artery disease, and 83%, 98%, 94%, 94%, and 94%, respectively, for left coronary artery disease.

Reversible intracranial changes in eclampsia demonstrated by MRI and MRA

CT and MRI allow visualization of eclampsia changes in the brain. Once case with reversible changes is reported.

Fast fluid-attenuated inversion-recovery MR of intracranial infections

PURPOSE

To assess the usefulness of fast fluid-attenuated inversion-recovery (FLAIR) MR sequences in the diagnosis of intracranial infectious diseases.

METHODS

We compared fast FLAIR images with conventional spin-echo images (T1- and T2-weighted) obtained in 20 patients with infectious diseases (six with encephalitis, five with brain abscesses, three with meningitis, two with meningoencephalitis, two with Creutzfeldt-Jakob disease, one with epidural empyema, and one with cysticercosis). Two neuroradiologists independently reviewed the FLAIR images and compared them with the conventional spin-echo images, obtaining agreement in all patients.

RESULTS

FLAIR images of diagnostic quality were obtained in 18 patients. In two patients, FLAIR images were degraded by motion. Lesions in the patients with encephalitis and meningoencephalitis were better delineated on FLAIR images than on spin-echo images. FLAIR images clearly depicted lesions in the basal ganglia in both patients with Creutzfeldt-Jakob disease. In patients with brain abscess, meningitis, cysticercosis, and epidural empyema, FLAIR images provided no more information than conventional spin-echo images, and the lesions were seen better on postcontrast T1-weighted spin-echo images.

CONCLUSION

Fast FLAIR images showed pathologic changes in intracranial infectious diseases better than or as well as conventional T2- and proton density-weighted spin-echo sequences. However, postcontrast T1-weighted spin-echo sequences resulted in better visibility of abscess, meningitis, cysticercosis, and epidural empyema than did FLAIR images.

Pancreatic ductal adenocarcinoma: preoperative assessment with helical CT versus dynamic MR imaging

PURPOSE

To compare helical computed tomography (CT) and dynamic, magnetic resonance (MR) imaging in the evaluation of pancreatic ductal adenocarcinoma.

MATERIALS AND METHODS

Dynamic MR images obtained with breath holding, 256 phase- and 512 frequency-encoding steps, 5-mm section thickness, phased-array multicoil, and double-dose gadolinium were available from 21 patients. Dynamic MR images were retrospectively compared with helical CT images in the evaluation of tumor detection, local tumor extension, and vascular involvement.

RESULTS

Tumors were detected on dynamic MR images of 19 of 21 (90%) patients and on helical CT scans of 16 (76%) patients. Dynamic MR imaging had equal or better sensitivity, accuracy, and agreement of tumor grade than did helical CT in the comparison of imaging findings and histopathologic findings. Dynamic MR imaging also had equal or better specificity than had helical CT in determination of local tumor extension and vascular involvement, except in the factors of duodenal invasion and portal venous system involvement. However, there was no statistically significant difference among any of these measurements.

CONCLUSION

Dynamic MR imaging may be better than helical CT in the preoperative detection and evaluation of local tumor extension and of vascular involvement of pancreatic ductal adenocarcinomas.