Characteristics and detectability of RARE technique

RARE is a kind of fast spin echo technique with large number of echo train and long TE. Because of long TE, signal from parenchyma is vanished and only liquid with long T2, such as bile, pancreatic juice, is detected. Compared to HASTE, signal from vessels like portal or hepatic vein is vanished either. Acquisition time of RARE is extremely short because it is single shot technique. So, on MRCP examination, RARE is good method for easily understanding of whole structure of biliary system because it is usually used as a projection image with thick slice. On the other hand, one should pay attention for shorter T2 bile and pancreatic juice. If their T2 is short, biliary system may not be shown with RARE.     

Non-breath-hold fast spin-echo versus breath-hold fast spin-echo and spoiled gradient-recalled echo MR imaging in the detection of hepatic tumors: correlation with surgical findings

OBJECTIVE: Our objective was to compare the sensitivity of non-breath-hold T2-weighted fast spin-echo with and without fat suppression, breath-hold T2-weighted fast spin-echo without fat suppression, and spoiled gradient-recalled echo (GRE) MR imaging for detecting hepatic tumors using surgical findings as the standard of reference. SUBJECTS AND METHODS: Eighteen patients with 36 surgically proven hepatic tumors had non-breath-hold T2-weighted fast spin-echo (6000/117 [TR/effective TE; echo train length, 16) MR imaging with and without fat suppression, breath-hold T2-weighted fast spin-echo MR imaging (2700/105; echo train length, 20), and spoiled GRE images (10.1/1.9; flip angle, 30 degrees) obtained before and after injection of a gadolinium chelate. Images were analyzed separately by two independent readers, with disagreements resolved by consensus reading. RESULTS: Non-breath-hold T2-weighted fast spin-echo MR imaging with and without fat suppression depicted 22 (61%; 95% confidence interval [CI], 43-77%) and 20 (56%; 95% CI, 37-72%) of 36 hepatic tumors, respectively. Breath-hold T2-weighted fast spin-echo imaging allowed detection of 19 (53%; 95% CI, 35-69%) of 36 hepatic tumors. Unenhanced and gadolinium chelate-enhanced spoiled GRE images allowed depiction of 18 (50%; 95% CI, 33-67%) and 29 (81%; 95% CI, 63-91%) of 36 hepatic tumors, respectively. Gadolinium chelate-enhanced spoiled GRE images allowed depiction of significantly more hepatic tumors than any of the other pulse sequences. CONCLUSION: Gadolinium chelate-enhanced spoiled GRE imaging is more sensitive than T2-weighted MR imaging obtained with a breath-hold or a non-breath-hold technique.     

Magnetic resonance angiography of the abdomen

The applications of abdominal MR angiography have been slow as compared with its applications in the head and neck mainly because of greater technical difficulties in dealing with respiratory motion and the use of the body coil, which has a poorer signal-to-noise ratio than head or surface coils. Further work is needed to reduce motion sensitivity and improve spatial resolution. Flow contrast and depiction of slowly flowing blood could be improved with the use of intravascular contrast agents. 52MR angiography is the imaging method of choice in the evaluation of the portal venous system, systemic veins, and aortic disease. With further technical improvements, it seems likely that applications of MR angiography will also be extended to smaller vessels.     

Stromal invasion by carcinoma of the cervix: assessment with dynamic MR imaging

OBJECTIVE: The purpose of this study was to evaluate dynamic MR imaging in assessing the depth of stromal invasion by carcinoma of the cervix and to compare dynamic MR imaging with T2-weighted and contrast-enhanced T1-weighted MR imaging. SUBJECTS AND METHODS: Forty-one patients with carcinoma that was clinically considered to be confined to the cervix were examined with T2-weighted, dynamic, and contrast-enhanced T1-weighted MR imaging before surgery. We evaluated enhancement patterns of the cervix and tumor and assessed the degree of stromal invasion with MR imaging. The degree of stromal invasion was divided into two groups: superficial disease (no stromal invasion or invasion of < or = 3 mm) and deep invasion (> 3 mm of stromal invasion). Then we compared these MR findings with histologic results for the depth of stromal invasion. RESULTS: With dynamic MR imaging, cervical carcinoma with deep invasion was seen as a focal enhanced area in the early dynamic phase. The cervical epithelium and stroma enhanced less vividly. In distinguishing deep invasion from superficial disease, we found the accuracy of T2-weighted MR images, dynamic MR images, and contrast-enhanced T1-weighted MR images to be 76%, 98%, and 63%, respectively. In particular, the detectability of 3.1-5.0 mm of stromal invasion with dynamic MR images was significantly higher than that with the other techniques: with T2-weighted MR images, we saw 3.1-5.0 mm of stromal invasion in 23% of patients; with dynamic MR images, in 92%; and with contrast-enhanced T1-weighted MR images, in none. Superficial disease was not revealed with any of the three MR techniques. CONCLUSION: We believe that dynamic MR imaging is superior to T2-weighted MR imaging and contrast-enhanced T1-weighted MR imaging when assessing the depth of invasion of cervical carcinoma.     

Sinusitis in the immunocompromised host

Using retrospective studies, we have investigated the possibility of obtaining characteristic findings of inflammatory pseudotumor of the liver by magnetic resonance (MR) imaging. We examined 8 patients (involving 8 masses) who had been histologically diagnosed as having an inflammatory pseudotumor in the liver. The histological studies were performed on an excised specimen of 1 mass, and on aspiration needle biopsy specimens and the clinical courses of the other 7 masses. T1 weighted images (T1WI) and T2 weighted images (T2WI) were obtained on MR imaging. MR imagings were analyzed for visualized patterns, patterns of internal structure and patterns of contrast enhancement of dynamic MR imaging. The 8 masses were visualized as hypointense on T1WI and hyperintense on T2WI by MR imaging. Dynamic MR imaging revealed that 1 mass was markedly enhanced peripherally while another mass was homogeneously enhanced, and that enhancement was most marked immediately after injection of contrast medium and then gradually disappeared. Vessels were observed in 4 masses (the portal vein in 2 masses, the hepatic vein in 1 mass, and portal and hepatic veins in 1 mass), and these vessels were clearly visualized on T1WI. The MR imaging findings from the early stage of an inflammatory pseudotumor showed a pattern similar to that of hepatic tumors with rich blood flow. The portal vein or hepatic vein was found in the tumor in half the patients, suggesting that this characteristic was useful for diagnosis of an inflammatory pseudotumor in the liver.     

Cognitive dysfunction and impaired organization of complex motility in degenerative parkinsonian syndromes

PURPOSE: Our purpose was to present imaging findings of six cases proven or supposed to be von Meyenburg complexes (VMCs) with a basis of reviewing the pathologic literature and to describe imaging points for the diagnosis of typical VMC along with its differential diagnosis. METHOD: Six cases were diagnosed as VMC of the liver with imaging modalities (one had histopathologic proof). Both ultrasound (US) and CT were available for all cases, and MRI was used for three cases. Follow-up with US, CT and/or MRI was performed in five cases. RESULTS: US detected varying abnormalities of the livers in four cases. CT and MRI revealed multiple or numerous intrahepatic tiny (usually < 5 mm) cystoid lesions in all of the cases. The lesions were scattered throughout the livers, and some of them were located more frequently adjacent to the medium-sized portal veins than to the hepatic veins of similar size on CT. Moreover, some lesions were apparently located in the subcapsular areas (up to the hepatic capsules). They were usually irregular in shape and showed no enhancement but increased in number by approximately 80-150% after administration of intravenous contrast medium. The T2-weighted MR images and MR cholangiopancreatography showed the lesions to be much more apparent and to be more numerous than T1-weighted images did. Follow-up of five cases with imaging modalities did not show remarkable change of the lesions. CONCLUSION: Despite our limited experience, VMC lesions seem to show some CT and MR features different from those of other multiple small hepatic lesions. They presented as multiple or numerous intrahepatic tiny cystoid lesions usually with irregular contour, scattered throughout the liver up to the subcapsular areas, and were detected in far greater number by enhanced CT or T2-weighted MR images than by unenhanced CT or T1-weighted images. They showed no remarkable change on long term follow-up imaging. We propose that a diagnosis of typical VMC could be made after analyzing CT or MR images carefully with good understanding of its pathologic basis, but imaging follow-up is necessary in oncology patients.     

Basic principles and historical consideration of MR cholangiopancreatography

Basic principle of MR cholangiopancreatography (MRCP) is heavily T2-weighted imaging (hydrography) to use bile and pancreatic juice as "natural contrast medium". Firstly developed sequence for MRCP was a CE-FAST sequence, which employed time-reversed FID signal. The current most popular sequences for MRCP are single-shot fast spin-echo sequences, which are divided into three types (2D single slice, 2D mutiple slice and 3D methods). The advantage of 2D single slice method is conveniently obtained projection imaging within a few seconds of examination time. Both 2D multiple slice and 3D methods consists of a MIP image and a series of source images. The MIP image creates global images of pancreatico-biliary system. The source images provide detailed evaluation of various anatomical structures and abnormalities. By using these sequences properly, MRCP can yield valuable informations of pancreatico-biliary diseases non-invasively.     

Only visual impressions are almost always present in long-term memories, and reported completeness, accuracy, and verbalizability of recollections increase with age

PURPOSE: To stage advanced cervical carcinoma with conventional or pharmacokinetic magnetic resonance (MR) imaging by correlating imaging findings with whole-mount specimens and histopathologic findings. MATERIALS AND METHODS: Twenty-six adult patients with primary cervical cancer (stages IIB-IVA) underwent T2-weighted turbo spin-echo (SE) MR imaging; gadolinium-enhanced, T1-weighted SE MR imaging; and gadolinium-enhanced, saturation-recovery, turbo fast low-angle shot MR imaging. All imaging findings were correlated with the whole-mount specimens and histopathologic findings. Signal intensity changes versus time were analyzed by using a pharmacokinetic model and parameter values displayed as a color-coded overlay. RESULTS: Histopathologic stages were IIB (n = 9), IIIB (n = 1), and IVA (n = 16). The overall accuracy for tumor staging was 73% for T2-weighted, 81% for T1-weighted, and 92% for pharmacokinetic MR imaging. Pharmacokinetic MR imaging was accurate (90%) in the diagnosis of tumor extension into the bladder and/or rectal wall but inaccurate (69%) in that of parametrial invasion. T2-weighted images were most accurate (86%) in the assessment of parametrial tumor extension but less accurate (69%) in that of bladder or rectal invasion. CONCLUSION: T2-weighted turbo SE images are still superior to contract medium-enhanced T1-weighted SE or pharmacokinetic MR images in the diagnosis of parametrial infiltration by uterine cervical carcinoma. However, pharmacokinetic MR imaging is a promising method for demonstrating and staging IVA disease.     

Hepatic cavernous hemangioma: appearance on T2-weighted fast spin-echo MR imaging with and without fat suppression

OBJECTIVE: The goals of our study were to define the morphologic appearance of cavernous hemangioma of the liver on T2-weighted fast spin-echo MR imaging and to determine if the use of fat suppression may quantitatively and qualitatively modify the MR imaging appearance of cavernous hemangioma. SUBJECTS AND METHODS: Twenty-six patients with cavernous hemangiomas of the liver were prospectively studied with T2-weighted MR imaging with a fast spin-echo technique with and without fat suppression. Thirteen patients had known hemangiomas for more than 2 years, with no change in size or morphology during this period. The remaining 13 patients had diagnoses based on dynamic CT and sonography and an absence of change in the morphology and size of their lesions during follow-up of more than 6 months (range, 6-12 months) after the MR imaging studies. Values for signal intensity and contrast-to-noise (C/N) ratios in cavernous hemangiomas that were obtained with and without fat suppression were compared. Images were qualitatively analyzed separately at identical level and window settings by two interpreters for morphologic features of cavernous hemangiomas. RESULTS: No significant difference was found between signal intensity values obtained using the fat-suppressed fast spin-echo MR imaging technique (5.62 +/- 1.14 [SD]) and those obtained without fat suppression (5.51 +/- 1.23). Values for C/N ratios obtained with the fat-suppressed fast spin-echo MR imaging technique (20.13 +/- 7.63) were significantly superior to those obtained without fat suppression (16.59 +/- 5.31) (p < .001). On T2-weighted fast spin-echo MR imaging without fat suppression, 100% of cavernous hemangiomas were hyperintense relative to the spleen, 90% had well-defined and sharp margins, 55% were isointense to CSF, and 76% were homogeneous. Without fat suppression, 34% of cavernous hemangiomas showed the combination of isointensity to CSF, well-defined margins, and homogeneity. On T2-weighted fast spin-echo MR imaging with fat suppression, all cavernous hemangiomas showed this same combination of features. CONCLUSION: Seventy-six percent of hepatic cavernous hemangiomas were homogeneous on T2-weighted fast spin-echo MR imaging, and 55% were isointense to CSF. However, only 34% of hepatic cavernous hemangiomas showed typical features. Although fat suppression significantly increased the C/N ratio of cavernous hemangiomas of the liver, fat suppression did not affect their morphologic appearance on T2-weighted fast spin-echo MR imaging.     

Chronic blockade of endothelin ETA receptors improves flow dependent dilation in resistance arteries of hypertensive rats

PURPOSE: To compare findings with magnetic resonance (MR) cholangiography with rapid acquisition with relaxation enhancement (RARE) and half-Fourier acquisition with single-shot turbo spin-echo (hereafter, half Fourier RARE) snapshot imaging techniques to those with endoscopic retrograde cholangiography (ERC). MATERIALS AND METHODS: Heavily T2-weighted thick-section (RARE) and thin-section (half-Fourier RARE) MR cholangiography were performed prospectively, on a 1.5-T imager, in the biliary tree of 61 consecutive patients before ERC. Findings at ERC were considered the standard of reference. The radiologist and endoscopist were blinded to each other's report. On- and off-site MR cholangiographic readings were performed to detect stones (n = 24), biliary dilatation (n = 34), or stenosis (n = 36). RESULTS: The sensitivity and specificity of MR cholangiography, respectively, calculated on a lesion-by-lesion basis, were 92.3% and 95.8% for cholangiolithiasis, 94.1% and 92.6% for duct dilatation, and 88.8% and 84.0% for stenosis. With snapshot MR cholangiography, on a patient-by-patient basis, differentiation between normal (n = 15) and abnormal (n = 46) results yielded a sensitivity of 92.4%, a specificity of 83.4%, and a positive predictive value of 95.6%. Pitfalls were caused by flow artifacts, compression by vessels, and low contrast between calculi and surrounding parenchyma. CONCLUSION: Snapshot MR cholangiography allowed noninvasive, accurate detection of biliary stones, strictures, and dilatation similar to that with ERC. Discrepancies regarding low-grade dilatation and strictures had no clinical relevance at retrospective review.     

Catheter ablation of ventricular tachycardia associated with remote myocardial infarction: utility of the atrial transseptal approach

BACKGROUND: To determine the magnetic resonance (MR) imaging features of hepatic metastases from leiomyosarcoma and determine the pathologic basis for the MR appearance of these neoplasms. METHODS: MR examinations of eight patients with a total of 16 hepatic metastases from leiomyosarcoma were retrospectively reviewed. Hepatic metastases originated from a primary gastrointestinal (n = 6), uterine (n = 1), or retroperitoneal (n = 1) leiomyosarcoma. Correlation between MR features and pathologic findings was performed in 11 metastases from which histologic material was obtained. RESULTS: Among the 10 metastases seen on T1-weighted MR images, nine were homogeneous and one was heterogeneous. The latter contained areas of necrosis and hemorrhage on pathologic examination. Among the 16 metastases seen on T2-weighted MR images, 12 were well delineated and completely homogeneous, with a marked hyperintense signal ("hemangiomalike" pattern). These neoplasms were composed of smooth fibrous tissue without macroscopically visible areas of necrosis on pathologic examination. The remaining four metastases were heterogeneous and contained varying degrees of necrosis and hemorrhage or gelatinous tissue. CONCLUSION: A hemangiomalike pattern is the most common feature on T2-weighted MR images. We found that homogeneous hyperintensity of hepatic metastases from leiomyosarcoma on T2-weighted MR image does not reflect cystic changes.     

An unusual hyperplastic hepatocellular nodule in a patient with hepatitis C virus-related liver cirrhosis

Recent advances in diagnostic imaging techniques have increased the likelihood of detecting novel nodular lesions of the liver. We report here a case of unusual hyperplastic hepatocellular tumor found in a 70-yr-old woman with hepatitis C virus-related cirrhosis. A mass was incidentally detected in the right lobe by abdominal ultrasonography and confirmed by computed axial tomography (CT). Magnetic resonance imaging demonstrated that the tumor had hyperintense signal with a small hypointense region in the center and a thin, hypointense rim on T1-weighted image and a hypointense signal on T2-weighted image. CT during hepatic arteriography showed that the tumor was hypodense with a central hyperdense region, whereas CT during arterial portography revealed that the tumor was isodense and surrounded by a thin circular hypodense band with a central hypodense region. These radiographic findings suggested a diagnosis of dysplastic nodule with malignant foci of hepatocellular carcinoma. The patient underwent tumor resection. Macroscopically, the tumor, 45 x 45 x 30 mm in size, was encapsulated and had a central stellate-like scar with radiating septa. Histological examination showed a hyperplastic hepatocellular tumor without cellular, nuclear or structural atypia. The central fibrous scar contained abundant small, artery-like and vein-like vessels, whereas there were no normal portal triads but rather several portal tract-like structures lacking bile ducts in the parenchyma of the tumor. Some of the portal tract-like structures were composed of artery-like and vein-like vessels, and the others possessed vein-like vessels only. There were no bile ducts in the tumor. The nontumorous liver tissue had evidence of macronodular cirrhosis. Finally, this tumor was regarded as an unusual type of hyperplastic hepatocellular nodule encountered in cirrhotic liver, characterized by the presence of central stellate-like fibrosis and the lack of bile ducts. Although the pathogenesis of the hyperplastic lesion is unclear, it may represent a focal regenerative hepatocellular response to localized circulatory disorder.     

New frontiers in the management of obstructive sleep apnoea syndrome

BACKGROUND: To report the dynamic magnetic resonance (MR) imaging findings of hepatolithiasis. METHODS: Dynamic MR images (fast spoiled gradient echo sequence with intravenous injection of gadopentate dimeglumine) and computed tomography, cholangiography, or angiography of nine patients with hepatolithiasis are analyzed. RESULTS: All affected hepatic segments showed atrophic changes and contained dilated intrahepatic ducts. These segments showed either iso- or hypointensity on T1-weighted imaging and hyperintensity on T2-weighted imaging. Preferential enhancement was noted throughout all phases of the dynamic study and persisted to delayed T1-weighted imaging in seven patients. In the last two patients, severe atrophic changes made evaluating signal intensity differences and enhancement patterns difficult. CONCLUSION: In addition to intrahepatic stones and biliary dilatation, segmental atrophy, signal intensity differences, and preferential and persistent enhancement are important MR findings of hepatolithiasis.     

Autoimmune pancreatitis: CT and MR characteristics

OBJECTIVE: Our goal was to elucidate the CT and MR imaging characteristics in patients with autoimmune pancreatitis, which is a reversible chronic pancreatitis with an autoimmune cause. CONCLUSION: On CT and MR imaging, a capsulelike rim, which is thought to correspond to an inflammatory process involving peripancreatic tissues, appears to be a characteristic finding of autoimmune pancreatitis. Also, diffuse pancreatic enlargement along with hypointensity on T1-weighted MR images and delayed enhancement on dynamic CT and MR studies are other features of this disorder.     

Paraganglioma of the cauda equina: a case report and review of the literature

The authors describe the technique of RARE sequences (Hennig, 1986) and their hydrographic application to urinary imaging, RARE urography. Heavily T2-weighted non-tomographic images of the urinary tract are obtained in less than 30 seconds, without contrast medium or ionizing radiation. The whole urinary tract is visualised on one image with a spatial resolution superior to that of sonography. The semiology of RARE urography is similar to that of the intravenous pyelogram. Silent kidneys are also visualised.     

Magnetic resonance imaging of acute stroke

In the investigation of ischemic stroke, conventional structural magnetic resonance (MR) techniques (e.g., T1-weighted imaging, T2-weighted imaging, and proton density-weighted imaging) are valuable for the assessment of infarct extent and location beyond the first 12 to 24 hours after onset, and can be combined with MR angiography to noninvasively assess the intracranial and extracranial vasculature. However, during the critical first 6 to 12 hours, the probable period of greatest therapeutic opportunity, these methods do not adequately assess the extent and severity of ischemia. Recent developments in functional MR imaging are showing great promise for the detection of developing focal cerebral ischemic lesions within the first hours. These include (1) diffusion-weighted imaging, which provides physiologic information about the self-diffusion of water, thereby detecting one of the first elements in the pathophysiologic cascade leading to ischemic injury; and (2) perfusion imaging. The detection of acute intraparenchymal hemorrhagic stroke by susceptibility weighted MR has also been reported. In combination with MR angiography, these methods may allow the detection of the site, extent, mechanism, and tissue viability of acute stroke lesions in one imaging study. Imaging of cerebral metabolites with MR spectroscopy along with diffusion-weighted imaging and perfusion imaging may also provide new insights into ischemic stroke pathophysiology. In light of these advances in structural and functional MR, their potential uses in the study of the cerebral ischemic pathophysiology and in clinical practice are described, along with their advantages and limitations.     

Immune responses associated with chronic fatigue syndrome: a case-control study

MR images of the liver in 13 patients with surgically proven intrahepatic cholangiocarcinoma were reviewed retrospectively and correlated to the histologic analysis of surgical specimens. We paid special attention to the peripheral liver tissue with ductal dilation but without tumorous involvement. High signal intensity was observed in the hepatic parenchyma with ductal dilation on T1-weighted spin-echo images (8 of 12) and spoiled gradient-recalled echo images (seven of seven), as compared with the contralateral hepatic lobe without duct dilation. The high signal intensity was not suppressed with fat saturation and showed enhancement after administration of contrast (11 of 12). Concurrent portal venous obstruction did not have significant effect on these findings (P < .05). Correlation with pathologic specimens suggested that this enhancement was associated with periportal fibrosis. The etiology of the high signal intensity on unenhanced spin echo or gradient-recalled T1-weighted image remains unclear. Radiologists should recognize these findings and should distinguish these from tumor involvement or the arterial buffer response caused by portal venous obstruction.     

Focal malignant hepatic lesions: MR imaging enhanced with gadolinium benzyloxypropionictetra-acetate (BOPTA)--preliminary results of phase II clinical application

PURPOSE: To investigate enhancement with gadolinium benzyloxypropionictetraacetate (BOPTA) at magnetic resonance (MR) imaging to detect focal malignant hepatic lesions. MATERIALS AND METHODS: A phase II trial was performed in 34 patients. Gd-BOPTA-enhanced spin-echo (SE) and gradient-recalled-echo (GRE) T1-weighted MR imaging were performed at 40 and 90 minutes after intravenous injection of 0.05 and 0.10 mmol/kg Gd-BOPTA. RESULTS: The percentage of enhancement in liver parenchyma was significantly (P<.05) increased on GRE T1-weighted compared with SE T1-weighted images at 40 and 90 minutes after injection of the higher dose and compared with SE and GRE T1-weighted images obtained with the lower dose. The contrast-to-noise ratio of metastases was significantly increased on GRE T1-weighted images (0.10 mmol/kg) at 90 minutes compared with precontrast images. Significantly more small primary metastases were detected on GRE T1-weighted images (0.10 mmol/kg) at 90 minutes compared with precontrast SE T1-weighted images. CONCLUSION: Gd-BOPTA is a safe hepatobiliary contrast agent that helps detection of small metastases.     

MR first pass imaging: quantitative assessment of transmural perfusion and collateral flow

Recent advances with fast switching gradient coils, and the optimization of magnetic resonance techniques for multislice imaging have made it possible to apply models of contrast agent transit for the quantification of myocardial perfusion, and determination of the transmural distribution of blood flow. This article summarizes some of these recent developments and presents examples of quantitative, multi-slice myocardial perfusion imaging studies in patients and animal models. Multi-slice, true first pass imaging, with high temporal resolution, and T1-weighted, arrhythmia insensitive contrast enhancement is used for the quantification of perfusion changes accompanying mild to severe ischemia. The first pass imaging technique and the modeling approach are sufficiently robust for fitting of tissue residue curves corresponding to a wide, physiologically realistic range of myocardial blood flows. In animals this was validated by comparison to blood flow measurements with radiolabeled microspheres as gold standard. It is demonstrated that with the proposed modeling approach one can determine the myocardial perfusion reserve from two consecutive MR first pass measurements under resting and hyperemic conditions. In patients with microvascular dysfunction the MR studies show for the first time that the myocardial perfusion reserve correlates with Doppler flow measurements (linear regression with slope of 1.02 +/- 0.09; r = 0.80). Since perfusion limitations usually begin in the subendocardium as coronary flow is gradually reduced, first pass imaging with the prerequisitie spatial and temporal resolution allows early detection of a mild coronary stenosis.     

Magnetic resonance imaging of renal lymphoma with computed tomography correlation

The magnetic resonance (MR) imaging and computed tomography (CT) findings in four patients (five kidneys) with non-Hodgkin's lymphoma involving the kidneys and perirenal spaces are presented. The patterns of disease in each case were as follows: bilateral renal nodules, infiltration in the perirenal space, infiltration in the perirenal space with renal involvement, and direct invasion from contiguous retroperitoneum. On plain CT, the lesions showed slight hyperdensity (three kidneys) and isodensity (two kidneys) as compared with normal renal parenchyma. But all lesions appeared as hypodense masses with more definite margins after contrast enhancement. MR imaging findings showed iso- or slight hypointense masses on T1-weighted images and definite hypointense masses on T2-weighted images as compared with the signal intensity of the renal cortex. Dynamic imaging and conventional delayed T1-weighted imaging following Gd-DTPA injection showed no significant enhancement of the lesions. In comparison with contrast enhanced CT, despite its poorer resolution, T2-weighted MR imaging showed nearly the same accuracy in the evaluation of number and extent of the lesions without contrast medium administration. MR imaging was also useful to evaluate the patency of vessel lumen surrounded by tumor mass and to determine the location and extent of huge lesions by its multiplanar imaging capabilities.