Imaging end-stage kidney disease in adults. Low-field MR imaging with magnetization transfer vs. ultrasonography

Purpose: To 1) assess the potential of magnetization transfer (MT)-weighted MR imaging to improve the often poor visibility of native kidneys in patients with a renal transplant; and 2) compare low-field MR imaging and ultrasonography (US) for imaging these fibrotic kidney remnants.Material and Methods: Seventy-two native kidneys of 36 patients were prospectively evaluated with US and MR. In low-field (0.1 T) MR imaging, T1-, T2- and MT-weighted sequences were used. MT-weighted images were compared with T2-weighted images in their ability to delineate the kidneys from their surroundings whereas US and MR were compared for detection of renal cysts and possible solid tumors.Results: MT-weighted images proved superior to conventional T2-weighted images in producing contrast between the kidney remnants and their fatty surroundings. Although US revealed a few small renal cysts that were not seen at MR images, no statistical difference was found between the two modalities in this respect.Conclusion: MT imaging, due to its unique protein-specific signal depression, offers significantly improved visualization and delineation of end-stage kidneys. US, because its better availability and cost-benefit ratio, remains the method-of-choice compared to low-field MR imaging in detecting cysts in multicystic kidneys. MR investigation is helpful in selected patients and may be used as an alternative.     

3T MR DW和BOLD对移植肾初步研究

目的:研究3.0T MR对移植肾DWI和BOLD成像的可行性.初步设定在3.0T MR上正常自体肾和正常移植肾的ADC值和R2*值范围.对比慢性移植肾病的ADC和R2*值,希望能无创性地加以鉴别.方法:对16例正常人及16例肾移植患者(8例为正常移植肾,8例慢性移植肾病)进行DWI和BOLD功能成像,在工作站上分别进行皮质和髓质ROI的定位,并记录ADC值和R2*值,对所得的结果进行统计学分析.结果:在3.0T MR上肾脏DWI和BOLD图像信噪比良好,能满足成像要求.自体肾和正常移植肾的皮髓质ADC值和R2*值的基线和变化范围均较以前报道的在1.5T上获得的高.慢性移植肾病的皮质ADC值、髓质R2*值及髓皮质R2*比值均较正常移植肾降低,并且有统计学意义.结论:3.0T MR扫描仪对肾脏DWI和BOLD功能成像是可行的,并且有利于对肾脏的功能研究,对慢性移植肾病的鉴别有一定帮助.     

MRI and CT findings of neurohypophyseal germinoma

OBJECTIVE: Magnetic resonance (MR) imaging and computed tomography (CT) findings of neurohypophyseal germinoma have not previously been described in detail. The purpose of the present study was to establish the spectrum of MR imaging and CT findings in neurohypophyseal germinomas. MATERIALS AND METHODS: MR and CT images of 13 consecutive patients (seven males, six females; mean age: 15 years; range: 6-31 years) with neurohypophyseal germinoma were retrospectively analyzed. The diagnosis had been made either histologically (n=8) or clinically according to established criteria (n=5). All patients had been examined using MR imaging and CT before treatment. RESULTS: On MR imaging, infundibular thickening (up to 16 mm) was observed in all 13 cases. Hyperintensity of the posterior pituitary on T1-weighted image was absent in all 13 cases (100%) and 12 of the 13 displayed central diabetes insipidus. Ten germinomas (77%) were isointense to cerebral cortex on T1-weighted image, but variable intensities were exhibited on T2-weighted image. MR images revealed intratumoral cysts in six cases (46%), most of which demonstrated intra-third ventricular extension. Eleven of the 13 cases (85%) revealed hyperdense solid components on unenhanced CT. Calcification was absent in all cases (100%). CONCLUSION: Infundibular thickening, absence of the posterior pituitary high signal on T1-weighted image, lack of calcification and hyperdensity on unenhanced CT are common imaging features of neurohypophyseal germinoma.     

Autosomal dominant polycystic kidney disease: MR imaging evaluation using current techniques

PURPOSE: To determine the MR imaging findings of autosomal dominant polycystic kidney disease using current imaging techniques. MATERIALS AND METHODS: We reviewed our five-year experience with MR imaging of autosomal dominant polycystic kidney disease (ADPKD) to determine the spectrum of appearance of kidney disease, the occurrence of cysts in other abdominal organs, the size and number of cysts in the kidneys and other organs, and the association with other benign or malignant disease. Thirty patients (17 men and 13 women, age range 30 to 88 years old) with ADPKD were included in this study. All patients were examined by MR imaging including T2-weighted single-shot echo-train spin-echo and pre- and post-gadolinium chelate spoiled gradient-echo imaging. RESULTS: All kidneys were involved with multiple, varying sized cysts scattered throughout the parenchyma. Giant renal cysts (>8 cm) were associated with pain in the only two patients who possessed them. Hemorrhage in renal cysts was observed in all kidneys with a heterogeneous pattern of involvement on non-contrast T1- and T2-weighted images, reflecting hemorrhage of varying age. The mean kidney size for the right kidney was 17.4 cm in length, 10.3 cm in transverse, and 9.4 cm in antero-posterior diameter (AP); and for the left kidney, 15.9 cm in the length, 9.3 cm in the transverse, and 9.3 cm in AP diameter. Other organs involved included the liver (22 patients), the pancreas (three patients), with two of the above-mentioned patients having both liver and pancreas cysts, and the spleen (one patient) who had both liver and splenic cysts. Massive liver involvement with large cysts was associated with abdominal pain. Malignant disease was present in five patients, including two patients with renal cell carcinoma, one with bladder cancer, one with lung cancer, and one patient with anal adenocarcinoma. Comparison of pre- and post-contrast T1-weighted images was essential to detect renal cancer. CONCLUSION: All kidneys in patients with ADPKD had extensive, varying-sized cysts and in all cases some cysts showed evidence of hemorrhage. The liver was the second most common organ to be involved with cystic disease, in 73% of patients. Large cysts in the kidneys and liver were associated with abdominal pain.     

Acute renal failure secondary to rhabdomyolysis. MR imaging of the kidney.

MR imaging of the kidney was performed in 6 patients with acute renal failure (ARF) secondary to rhabdomyolysis caused by snake bite (n = 4), crush injury (n = 1), and carbon monoxide poisoning (n = 1). A test for urine myoglobin was positive in all 6 patients and MR imaging was done 6 to 18 days after the causative event of the rhabdomyolysis. MR images in all 6 patients showed globular swelling of the kidneys, preserved corticomedullary contrast on T1-weighted images, and obliteration of corticomedullary contrast on T2-weighted images. Unlike other medical renal diseases in which corticomedullary contrast is lost on T1-weighted images, preservation of the corticomedullary contrast on T1-weighted MR images with globular renal swelling was a constant finding in patients with ARF secondary to rhabdomyolysis.     

MR findings of renal cortical necrosis

PURPOSE: Evaluating the MR findings of renal cortical necrosis was the purpose of this study. METHOD: Eight series of T1-/T2-weighted (n = 8) and contrast-enhanced T1-weighted (n = 4) MR images in six patients with renal cortical necrosis diagnosed by renal biopsy (n = 4) or on clinical grounds (n = 2) were reviewed. In those who had follow-up MRI (n = 2) or comparable CT (n = 3), interval changes of MR findings and comparison with CT images were done. RESULTS: Swollen kidney with dark signal intensity rim involving the inner cortex and column of Bertin was noted on T2-and T1-weighted images. It was more conspicuous on T2-weighted images. The lesion did not enhance and was differentiated from uninvolved renal parenchyma. In the follow-up MRI, thickened dark signal intensity was more prominent and proved to be calcification or fibrosis. CONCLUSION: MRI, especially T2-weighted and contrast-enhanced T1-weighted imaging, was helpful in evaluating renal cortical necrosis.     

Kidney changes after extracorporeal shock wave lithotripsy: appearance on MR imaging

The occurrence of changes in the kidneys after extracorporeal shock wave lithotripsy (ESWL) was evaluated with magnetic resonance (MR) imaging in 34 patients, utilizing T1-weighted spin-echo pulse sequences. Five of the 34 patients underwent bilateral ESWL therapy before MR imaging. Of the 39 kidneys studied, 29 (74%) showed one or more changes on MR imaging: subcapsular or perinephric fluid (n = 10), focal (n = 16) or diffuse (n = 8) loss of the corticomedullary junction (CMJ), and focal areas of increased (n = 7) or decreased (n = 3) signal intensity. The CMJ changes were more prominent with increasing numbers of shock waves administered during the procedure. These relatively subtle changes detected on MR imaging may not be apparent with other imaging techniques. The long-term clinical significance of these findings is not yet known, although no apparent serious renal pathologic condition was detected.     

Comparison of true FISP with turbo SE in ovarian imaging.

PURPOSE: To compare the signal pattern of True FISP (true fast imaging with steady state precession) with that of T2-weighted TSE (turbo spin echo) sequencing in several ovarian pathologies and to clarify the pathologies that may be misdiagnosed when True FISP is used as a fast T2-weighted MR (magnetic resonance) imaging technique. METHODS: A total of 56 patients with 58 ovarian lesions were prospectively studied. The histopathological diagnoses were surgically confirmed in all patients. All MR images were acquired with a 1.5T MR scanner. After routine MR examination (T2-weighted sagittal imaging with a turbo spin echo sequence and T1 and T2 transverse imaging with a spin echo and turbo spin echo sequence, respectively), True FISP was performed in the sagittal plane with a fat-saturation technique. The acquisition times for the True FISP and TSE techniques were 27 s and 4 min, 42 s, respectively. Three radiologists interpreted all images according to three grading scores and with particular reference to the difference in signal pattern between the two sequences (1=similar signal patterns in the ovarian lesions in both True FISP and TSE images; 2=partially different signal patterns in both True FISP and TSE images; and 3=conflicting signal patterns in both True FISP and TSE images). RESULTS: Those assigned a score of "1" included 30 patients with 30 ovarian lesions (12 malignant lesions and 18 benign lesions); those assigned a score of "2" included 10 patients with 10 lesions (two malignant and eight benign); and those assigned a score of "3" included 16 patients with 18 ovarian lesions (two malignant and 16 benign). With the influence of the fat-suppression technique excluded, eight ovarian lesions showed conflicting signal patterns between the two sequences and high signal intensity of hemorrhaging in the corresponding lesion in T1-weighted images. Lesions of both high and low signal intensity in TSE images appeared as lesions of high signal intensity in True FISP images. About 14% (8/56 lesions) of the True FISP and TSE signal patterns in ovarian pathology were conflicting in this study. CONCLUSION: The results indicate that the True FISP technique cannot replace the T2-weighted TSE technique in the evaluation of ovarian pathology. T1-weighted images with or without fat suppression are required for the evaluation of ovarian lesions with FISP images.     

Functional evaluation of hydronephrosis by diffusion-weighted MR imaging. Relationship between apparent diffusion coefficient and split glomerular filtration rate

PURPOSE: To determine the relationship between apparent diffusion coefficient (ADC) values measured by diffusion-weighted MR imaging and split renal function determined by renal scintigraphy in patients with hydronephrosis. MATERIAL AND METHODS: Diffusion-weighted imaging on a 1.5 T MR unit and renal scintigraphy were performed in 36 patients with hydronephrosis (45 hydronephrotic kidneys, 21 non-hydronephrotic kidneys). ADC values of the individual kidneys were measured by diffusion-weighted MR imaging. Split renal function (glomerular filtration rate (GFR)) was determined by renal scintigraphy using 99mTc-DTPA. The relationship between ADC values and split GFR was examined in 66 kidneys. The hydronephrotic kidneys were further classified into three groups (severe renal dysfunction, GFR <10 ml/min, n=7; moderate renal dysfunction, GFR 10-25 ml/min, n= 10; normal renal function, GFR >25 ml/ min, n=28), and mean values for ADCs were calculated. RESULTS: In hydronephrotic kidneys, there was a moderate positive correlation between ADC values and split GFR (R2=0.56). On the other hand, in nonhydronephrotic kidneys, poor correlation between ADC values and split GFR was observed (R2=0.08). The mean values for ADCs of the dysfunctioning hydronephrotic kidneys (severe renal dysfunction, 1.32 x 10(-3) +/- 0.18 x 10(-3) mm2/s; moderate renal dysfunction, 1.38 x 10(-3) +/- 0.10 x 10(-3) mm2/s) were significantly lower than that of the normal functioning hydronephrotic kidneys (1.63 x 10(-3) +/- 0.12 +/- 10(-3) mm2/s). CONCLUSION: These results indicated that measurement of ADC values by diffusion-weighted MR imaging has a potential value in the evaluation of the functional status of hydronephrotic kidneys.     

MR assessment of iodinated contrast-medium-induced nephropathy in rats using ultrasmall particles of iron oxide

The purpose of this study was to determine the diagnostic value of ultrasmall particles of iron oxide (USPIO)-enhanced MR imaging at different concentrations to evaluate experimental nephropathy. This study was conducted in 23 uninephrectomized rats using a model of iodinated contrast media-induced renal failure. Eleven rats received selective intra-arterial renal administration of diatrizoate (370 mg I/m1) and were compared to two control groups, including five animals injected with isotonic saline and seven noninjected animals. MR imaging was performed 28 hours after the procedure, including T1- and T2-weighted images before and after intravenous administration of successively 5 μmol Fe/kg and 60 μmol/kg of USPIO. Results were interpreted qualitatively and quantitatively with respect to pathologic data, and differences were studied statistically. The maximal signal intensity decrease was noted in normal kidneys in cortex (?65 ± 4%) and medulla (?84 ± 5%) on T2-weighted images after injection of 60 μmol/kg of USPIO. At this dose, diseased kidneys displayed less signal intensity decrease than normal kidneys on T2-weighted images (p = .05). Moreover, qualitative analysis showed that the highest sensitivity and specificity to diagnose kidney involvement were obtained with T2-weighted MR images (75% and 91%, respectively) when 60 μmol/kg of USPIO were used (p < .01). USPIO should be useful for in vivo evaluation of the severity of experimentally induced iodinated contrast media renal impairment in animals.     

MR-guided RF thermal ablation of the kidney in a porcine model.

OBJECTIVE: The purpose of the study was to evaluate the ability of MR imaging to reveal RF interstitial thermotherapy in the porcine kidney, as a model for future human trials, and to provide guidance for RF probe insertion. SUBJECTS AND METHODS: Ten MR-guided RF ablations were performed in the kidneys of three pigs. A 17-gauge monopolar RF probe electrode was inserted into the renal cortex using MR guidance, and RF was applied for 10 min. After postprocedure imaging (T2-weighted, turbo short inversion time inversion recovery [STIR], and T1-weighted sequences), the kidneys were harvested for pathologic examination. RESULTS: Successful RF probe placement was accomplished in all cases; the interventional procedure time for probe insertion ranged from 4 to 15 min. The thermal lesion size varied from 7 to 14 mm perpendicular to the probe track and was best seen on turbo STIR images. Turbo STIR had the highest renal cortex-to-RF thermal lesion contrast-to-noise ratio with an average of 4.4 +/- 3.5. Turbo STIR imaging never overestimated pathologic lesion diameter with a mean difference of 1.5 +/- 1.4 mm. Three subcapsular hematomas occurred. which could be detected immediately on postprocedure imaging. CONCLUSION: MR-guided RF thermal ablation in the porcine kidney was found to be feasible, but minor complications occurred. Induced thermal lesion size was best monitored using turbo STIR images. In the future, RF ablation may offer an alternative treatment option for renal cancer.     

MR imaging and MR arthrography of paraglenoid labral cysts

OBJECTIVE: We investigated the pathophysiology of paraglenoid labral cysts on the basis of MR imaging, MR arthrography, and cyst aspiration. MATERIALS AND METHODS: From 2211 MR imaging examinations, 51 (2.3%) cysts in 46 patients were identified. MR arthrography (n = 5), cystography (n = 1), arthroscopy (n = 17), percutaneous needle aspiration (n = 4), and medical records were also reviewed (n = 46). RESULTS: On MR imaging and arthrography, cysts were best viewed on T2-weighted images. Mean cyst diameter and volume were 2.2 cm and 2.8 cm3, respectively. Fifty-seven percent of cysts were located adjacent to the posterior labrum. On MR imaging and arthroscopy, a labral tear was identified in 27 (53%) and 15 (88%) patients, respectively. Eight cysts that caused compression neuropathy were large (mean size, 3.1 cm; p = 0.04) and located next to the posterior or inferior labrum. In four of five patients, MR arthrograms showed no intraarticular contrast material in the cyst. Cystograms showed no communication with the glenohumeral joint space, and cyst aspiration resulted in temporary symptom relief; however, cysts recurred in three of four patients. CONCLUSION: Most paralabral cysts are associated with labral tears. Paralabral cysts may be difficult to identify on MR arthrography unless a T2-weighted sequence is performed. Direct communication between a cyst and joint space rarely occurs. A posterior or inferior cyst may cause compression neuropathy of the suprascapular or axillary nerve, respectively. Cyst aspiration may result in temporary relief of symptoms, but an untreated labral tear should be suspected if cysts recur.     

Hemorrhagic fever with renal syndrome: MR imaging of the kidney

Magnetic resonance (MR) imaging of the kidneys was performed in 14 patients with a severe form of hemorrhagic fever with renal syndrome (HFRS), a major public health problem in Far Eastern Asia. To the authors' knowledge, this is the first report of renal assessment with MR imaging in HFRS. Three MR imaging studies were done while patients were in the oliguric phase, 19 were done during the diuretic phase, and three were done during the convalescent phase. The authors differentiated the cortex and the medulla in all 21 T1-weighted examinations and all 25 T2-weighted examinations. Seven T1-weighted examinations (33%) and 20 T2-weighted examinations (80%) showed low signal intensity along the outer portion of the medulla, which thus enabled differentiation from the inner medulla. Low signal intensity along the medulla (especially the outer medulla) on T2-weighted images, possibly representing medullary hemorrhage, is fairly constant and characteristic on MR images of the kidneys in patients with HFRS.     

Renal neoplasms amenable to partial nephrectomy: MR imaging.

PURPOSE: To determine the magnetic resonance (MR) imaging characteristics of renal lesions in patients who undergo technically successful partial nephrectomy. MATERIALS AND METHODS: Between February 1991 and September 1997, 38 patients (41 lesions) who underwent partial nephrectomy at a single institution were preoperatively evaluated with contrast material-enhanced, multiplanar, surface-coil MR imaging. Imaging findings that could affect the decision to perform partial nephrectomy were retrospectively evaluated: tumor size; tumor location; presence of pseudocapsule; suspected tumor invasion of renal sinus fat, renal collecting system, renal vein, or perinephric fat; and morphologic and physiologic status of the contralateral kidney. Correlation was made with surgical and pathologic findings. RESULTS: Thirty-three of 41 lesions (80%) were renal cell carcinomas, five were oncocytic neoplasms (12%), two were hemorrhagic cysts (5%), and one was an angiomyolipoma (2%). Twenty-four of 41 (59%) lesions had pseudocapsules. In most cases, the perinephric fat (n = 38 [93%]), the renal sinus fat (n = 31 [76%]), and the renal collecting system (n = 39 [95%]) were correctly interpreted as being uninvolved by tumor. CONCLUSION: Renal neoplasms amenable to partial nephrectomy can be identified and characterized with contrast-enhanced, multiplanar, surface-coil MR imaging.     

Is true FISP imaging reliable in the evaluation of venous thrombosis?

OBJECTIVE: The objective of our study was to evaluate the accuracy of true fast imaging with steady-state precession (FISP) in the diagnosis of venous thrombosis using gadolinium-enhanced 3D T1-weighted gradient-echo images and correlative imaging as the gold standard. MATERIALS AND METHODS: Twenty-five MR examinations were retrospectively reviewed independently by two radiologists to rule out thrombosis in the central veins of the body. The presence of venous thrombus was assessed separately in 80 veins using true FISP and gadolinium-enhanced T1-weighted images. Diagnosis was confirmed by another imaging technique (sonography, CT, and/or conventional venography) in all positive cases. Negative examinations were confirmed using imaging, clinical follow-up, or both. RESULTS: Venous thrombosis was present in 25 veins in 18 patients. True FISP images had a lower sensitivity (66%) and specificity (70.9%) for the diagnosis of venous thrombosis than gadolinium-enhanced MR images (p < 0.01). CONCLUSION: True FISP images have lower sensitivity and specificity in the diagnosis of venous thrombosis than gadolinium-enhanced T1-weighted gradient-echo images. True FISP images should not be used exclusively for the diagnosis of venous thrombosis.     

Renal allografts: evaluation by MR imaging

The value of magnetic resonance (MR) imaging in assessing renal transplants was prospectively studied in 45 patients with 46 allografts. Four allografts were imaged at two different times, and separate diagnoses were given for both examinations. Therefore, this study was based on 50 proved diagnoses: nine normally functioning allografts, four allografts with acute tubular necrosis (ATN), 29 with acute rejection, one with chronic rejection, five with cyclosporin nephrotoxicity, and two with local inflammation secondary to adjacent abscess. Twenty-seven of the allografts had concomitant fluid collections. Normal renal structures with preservation of corticomedullary contrast (CMC) on T1-weighted images were demonstrated in all the normally functioning allografts. Decreased or absent CMC on T1-weighted images, reflecting a long T1 relaxation time for cortex, was found to be the most consistent sign of acute renal allograft rejection (27/29). No abnormalities on on MR images were observed in allografts compromised by cyclosporin nephrotoxicity. Hydronephrosis of the renal allograft was easily diagnosed with MR. Perirenal abscess (three cases) and perirenal hematomas (five cases), because of their higher MR signal intensity on T1-weighted images (TR = 0.5 sec, TE = 28 msec), could be differentiated from clinically insignificant postoperative fluid seromas (seven cases), lymphoceles (11 cases), and urinoma (one case).     

Magnetic resonance imaging of renal involvement in genetically studied patients with tuberous sclerosis complex

Purpose

To evaluate renal involvement in tuberous sclerosis complex (TSC).

Materials and methods

A series of 24 TSC patients (19 with genetically demonstrated disease), underwent abdominal 1.0-T MR imaging with axial/coronal T1- and T2-weighted scans, with/without fat saturation. We looked for angyomiolipomas (AMLs) and cysts in 47 kidneys of 24 patients. We evaluated the percentage of parenchymal involvement by manual contouring on the coronal scans in 39 kidneys of 20 patients.

Results

We detected AMLs in 15/24 (63%) patients and in 27/47 (57%) kidneys, cysts in 14/24 (58%) and in 26/47 (55%); respectively. AMLs were found in 2/4 TSC1 and in 11/15 TSC2 patients, cysts were found in 2/4 TSC1 and in 9/15 TSC2 patients. The global renal involvement ranged from 0 to 32% (median, 18%) in TSC1 and from 0 to 100% (median, 39%) in TSC2 patients. A fair correlation (r = .464) was found between patient’s age and renal involvement, a good correlation (r = 0.655) between renal involvement and creatinine clearance.

Conclusion

Renal parenchyma of TSC patients can be evaluated with MR imaging. A detectable renal involvement was found in 83% of patients, higher in TSC2 than in TSC1. Renal function seems to correlate with renal involvement quantified with MR imaging.     

Measurement of the apparent diffusion coefficient in diffuse renal disease by diffusion-weighted echo-planar MR imaging.

The purpose of this study was to determine the relationship between the apparent diffusion coefficient (ADC) and diffuse renal disease by diffusion-weighted echolanar magnetic resonance (MR) imaging (EPI). Thirty-four patients were examined with diffusion-weighted EPI. The average ADC values were 2.55 x 10(-3) mm2/sec for the cortex and 2.84 x 10(-3) mm2/sec for the medulla in the normal kidneys. The ADC values in both the cortex and medulla in chronic renal failure (CRF) kidneys and in acute renal failure (ARF) kidneys were significantly lower than those of the normal kidneys. In renal artery stenosis kidneys, the ADC values in the cortex were significantly lower than those of the normal and the contralateral kidneys. In the cortex, ADC values were above 1.8 x 10(-3) mm2/sec in all 32 normal kidneys, ranging from 1.6 to 2.0 x 10(-3) mm2/sec in all 8 ARF kidneys, and below 1.5 x 10(-3) mm2/sec in 14 of 15 CRF kidneys. In the medulla, there was considerable overlap in the ADC values of the normal and diseased kidneys. There was a linear correlation between ADC value and sCr level in the cortex (r = 0.75) and a weak linear correlation in the medulla (r = 0.60). Our results show that diffusion-weighted MR imaging may be useful to identify renal dysfunction.     

MR imaging of acute renal cortical necrosis. A case report.

MR imaging of a patient with acute renal cortical necrosis secondary to massive bleeding following an abortion is presented. The kidneys were enlarged with a high signal intensity observed in the renal cortex on both T1- and T2-weighted images. Follow-up MR imaging showed thinned renal cortex of low signal intensity on both pulse sequences representing renal cortical calcification which was confirmed on conventional radiography and CT.     

原发性纵隔囊肿的影像学表现

目的分析纵隔囊肿的影像学特点，提高对不同类型囊肿不典型表现的认识和诊断水平。方法回顾性分析经手术病理证实的44例纵隔囊肿的CT和（或）MRI资料（其中28和26例分别行CT和MR检查，10例同时行CT和MR检查），分析其影像学表现。结果囊肿位于前、中、后纵隔者分别为13、18和11例，位于前中纵隔者2例。支气管囊肿和心包囊肿位于不典型部位者分别为7和5例。CT密度近似于水者12例，占42．9％（12／28）。MR T2WI病变均为等或高于脑脊液的长T2信号，1例水成像上信号有衰减。近似于脑脊液的长T1信号者8例，占30．8％（8／26）。MRI信号不均匀者5例，原因各异。误诊14例。结论后纵隔和前纵隔CT高密度和厚壁的囊肿易被误诊为肿瘤性病变；中纵隔气管旁的心包囊肿易被误诊为支气管囊肿。MRI有助于诊断CT高密度的纵隔囊肿。MRI信号不均匀或水成像上信号衰减足误诊的原因。