Utility of gadolinium-enhanced MR urography in detection of bladder carcinoma

Objectives

To evaluate the diagnostic accuracy of MR urography (MRU) in detecting bladder carcinoma.

Methods

A retrospective review of 107 MRU exams obtained to evaluate for possible upper urinary tract urothelial carcinoma from 5/2005 to 5/2009 was performed by two experienced abdominal radiologists. Interpretation of the presence or absence of bladder carcinoma and lesion conspicuity in each imaging phase was made using 5-point confidence grading scales. Exams included 3D T1-weighted spoiled gradient-recalled echo images through the kidneys, ureters and bladder in the coronal plane during parenchymal phases and in both coronal and axial planes during pyelographic phases after intravenous administration of gadolinium and furosemide. Standard of reference was cystoscopy or cystectomy within 30 days of MRU. Statistical measures of performance, including receiver operating characteristics area under the curve (Az) values were calculated.

Results

Bladder carcinoma was present in 26/107 patients (24%). Sensitivity, specificity, accuracy, positive predictive value, negative predictive value and Az value were 73.1%, 91.4%, 86.9%, 73.1%, 91.4%, 0.89 for the first reviewer, and 84.6%, 75.3%, 77.6%, 52.4%, 93.8%, 0.86 for the second. Lesion conspicuity was superior on the parenchymal phase compared to the pyelographic phase (p = 0.04).

Conclusions

MRU obtained for suspicion of upper urinary tract TCC has a moderate accuracy in detecting bladder carcinoma.     

Feasibility and utility of respiratory-gated, gadolinium-enhanced T1-weighted magnetic resonance urography in children

RATIONALE AND OBJECTIVES: To evaluate the feasibility and utility of respiratory-gated, gadolinium-enhanced T1-weighted magnetic resonance (MR) urography in children. METHODS: In a prospective study, 30 consecutive children, aged 3 weeks to 13.8 years, underwent MR urography. After intravenous injection of low-dose furosemide and gadopentetate dimeglumine, respiratory-gated, coronal, T1-weighted 3D-gradient-echo sequences were obtained at 1.5 T 5 to 30 minutes after contrast administration. Postprocessing of the data was performed using a maximum-intensity projection algorithm. In addition, precontrast half-Fourier rapid acquisition with relaxation enhancement MR urograms were obtained in 29 children. RESULTS: Respiratory-gated, T1-weighted MR urography was successfully performed in all children without the need for sedation. Compared with the final diagnosis, prospective analysis of MR urography images revealed the correct diagnosis in 56 of 58 pelvicaliceal systems (96%). The ureteral morphology was correctly evaluated in 59 of 64 ureters (92%). The method showed limited efficiency for evaluating nonfunctioning renal units. CONCLUSIONS: Respiratory-gated, gadolinium-enhanced T1-weighted MR urography is a feasible and effective diagnostic tool in the assessment of upper urinary tract morphology in children. It is especially useful in depicting nondilated collecting systems and ureters.     

MR urography: examination techniques and clinical applications

Modern MR urography is performed on the basis of two different imaging strategies, which can be used complementarily to cover almost all aspects in the diagnosis of upper urinary tract diseases. The first technique utilizes unenhanced, heavily T2-weighted pulse sequences to obtain static-fluid images of the urinary tract. T2-weighted MR urograms have proved to be excellent in the visualization of the markedly dilated urinary tract, even if the renal excretory function is quiescent. Static-fluid MR urography is less suitable for imaging of disorders that occur in the nondilated collecting system. The second MR urography technique is analogous to the methodology of conventional intravenous pyelography and is, therefore, designated as excretory MR urography. For this purpose, a non-nephrotoxic gadolinium chelate is intravenously administered and after its renal excretion, the gadolinium-enhanced urine is visualized using fast T1-weighted gradient-echo sequences. The combination of gadolinium and low-dose furosemide (5–10 mg) is the key for achieving a uniform distribution of the contrast material inside the entire urinary tract and, secondly, to avoid high endoluminal gadolinium concentrations, which cause signal loss of the urine due to T2^* effects. Gadolinium excretory MR urography allows to obtain high-quality images of both nondilated and obstructed urinary tracts in patients with normal or moderately impaired renal function. This article reviews the principles of T2- and T1-weighted MR urography in detail and informs how to use these techniques safely in potential clinical applications such as chronic urolithiasis, intrinsic and extrinsic tumor diseases, and congenital anomalies. Magnetic resonance urography performed in combination with standard MR imaging offers a potential to reduce the need for invasive retrograde pyelography. Although the economic aspect is still problematic, it is obvious that MR urography will continue to increase its role in clinical uroradiology. Received: 7 July 2000 Revised: 21 August 2000 Accepted: 21 August 2000     

CT and MR imaging features of oral and maxillofacial hemangioma and vascular malformation

PURPOSE: To present CT and MR images and compare CT and MRI features of oral and maxillofacial hemangioma and vascular malformation. MATERIAL AND METHODS: The clinical materials consisted of nine vascular tumors from nine patients examined by both CT and MR scanners between November 1996 and March 2002. Both CT and MR images were retrospectively evaluated. The following features were evaluated: detectability of the lesion, border of the lesion, tumor margin, inner nature of the lesion, contrast between the lesion and surrounding tissues, degree of CT value or signal intensity of the lesion, enhancement of contrast medium, inner nature of the lesion after contrast medium injection, detectability of phleboliths and detectability of bone resorption. RESULTS: In two patients, we could not detect lesions in any of the CT images because of artifacts from the teeth and/or dental restorations. In contrast, we could detect all lesions on T2-weighted MR images and contrast enhanced T1-weighted MR images. On T2-weighted images with the fat suppression technique, tumors tended to show higher contrast compared to surrounding tissues. CONCLUSION: T2-weighted images with the fat suppression technique and contrast enhanced T1-weighted images with the fat suppression technique were very useful for the detection of vascular lesions. Observation from optional directions (axial, coronal and sagittal images) seemed appropriate for delineating the extension of the tumor. Phleboliths detectability on CT images was superior to that on MR images.     

CT urography

With the advent of multi-detector row CT scanners, evaluation of the urothelium of the entire urinary tract with high-resolution thin sections during a single breath-hold has become a reality. Multidetector CT urography (MDCTU) is a single examination that allows evaluation of potential urinary tract calculi, renal parenchymal masses, and both benign and malignant urothelial lesions. Initial results with this new technique are encouraging. Current investigations of MDCTU focus on methods to improve opacification and distension of the upper urinary tract-the collecting systems, pelvis, and ureters. The role of abdominal compression, infusion of saline and/or furosemide, and optimal time delay of excretory phase imaging is being explored. Upper tract urothelial malignancies, including small lesions less the 5 mm in diameter, can be detected with high sensitivity. Methods to reduce radiation exposure are being explored, including split-bolus contrast injection techniques that combine nephrographic and excretory phases into a single phase. It is likely that in the near future, radiological evaluation of significant unexplained hematuria or of known or prior urothelial malignancy will consist of a single examination--MDCTU.     

Contrast enhancement of small hepatocellular carcinoma: usefulness of three successive early image acquisitions during multiphase dynamic MR imaging.

OBJECTIVE: The purpose of this study was to document the usefulness of early triphasic image acquisition during gadolinium-enhanced multiphase dynamic MR imaging for the detection of contrast enhancement in small hepatocellular carcinoma. SUBJECTS AND METHODS: Dynamic MR imaging was performed in 332 patients at 1.5 T using a T1-weighted fast low-angle shot sequence (TR range/TE, 113-130/4.1; flip angle, 80 degrees). With the start of bolus injection of gadolinium dimeglumine (0.1 mmol/kg) into the antecubital vein, three sets of contrast-enhanced images of the entire liver were obtained serially at 10, 35, and 60 sec. Contrast enhancement of the tumor detected on each phase was evaluated in conjunction with the unenhanced T1-weighted images for 52 patients with small hepatocellular carcinomas up to 2 cm in diameter (n = 79). RESULTS: The first phase images depicted a larger number (n = 57) of contrast enhancement of small hepatocellular carcinoma tumors than the second (n = 44) or third phase images (n = 14). Twenty-six lesions were enhanced only during the first phase, and nine, during the second phase. The detection rate of contrast enhancement in the combination of first and second phases was the same as the overall detection rate for all three phases (70/79, 89%) and significantly higher than those of each phase. CONCLUSION: Early multiple image acquisition is helpful for the assessment of small hepatocellular carcinoma and is enabled by the high detection rate of contrast enhancement regardless of individual variations in the timing of enhancement.     

CT urography

With the advent of multi-detector row CT scanners, evaluation of the urothelium of the entire urinary tract with high-resolution thin sections during a single breath-hold has become a reality. Multidetector CT urography (MDCTU) is a single examination that allows evaluation of potential urinary tract calculi, renal parenchymal masses, and both benign and malignant urothelial lesions. Initial results with this new technique are encouraging. Current investigations of MDCTU focus on methods to improve opacification and distension of the upper urinary tract-the collecting systems, pelvis, and ureters. The role of abdominal compression, infusion of saline and/or furosemide, and optimal time delay of excretory phase imaging is being explored. Upper tract urothelial malignancies, including small lesions less the 5 mm in diameter, can be detected with high sensitivity. Methods to reduce radiation exposure are being explored, including split-bolus contrast injection techniques that combine nephrographic and excretory phases into a single phase. It is likely that in the near future, radiological evaluation of significant unexplained hematuria or of known or prior urothelial malignancy will consist of a single examination—MDCTU.     

肝细胞癌射频治疗后的磁共振表现

目的：评价MRI平扫及Gd-DTPA动态增强对射频治疗肝细胞癌疗效随访的价值。材料和方法：回顾性分析了55例RF术前及术后的MRI表现,并与活检及长期随访结果进行对照。结果：RF术前病灶在T1加权上多呈相对低信号、T2加权像上呈相对高信号,RF术后病灶转变成T1加权较高信号、T2加权均匀一致的等低信号,残存的癌结节表现为病灶周围包膜不规整或周边小结节并在动态增强时呈单峰型“快进快出”强化表现,活检提示癌灶残存。结论：MR平扫评价RF的疗效基本可靠,动态增强能进一步提高评价信心及准确率。RF术后定期MR随访具有重要意义。     

Contrast enhancement patterns of acute spinal epidural hematomas: a report of two cases

The MR finding of an acute spinal epidural hematoma (SEH) can mimic epidural neoplastic or inflammatory lesions, because acute SEH appears hypointense on T1-weighted images and hyperintense on T2-weighted images. We report on two cases of acute SEH with unusual contrast enhancement patterns on MR images. Contrast enhancement can be an MR finding of acute SEH, especially in bleeding diathesis, which indicates an active lesion that needs early diagnosis and management.     

臂丛神经鞘瘤的MRI表现与手术对照研究

目的:评价臂丛神经鞘瘤的MRI表现,并与手术所见对照分析,以期对临床诊治有所裨益。材料和方法:经手术和病理证实的36例臂丛神经鞘瘤,术前均行MRI检查。所有患者MRI检查序列包括轴位T2WI(STIR),增强前后横断面、斜矢状面和冠状面T1WI(增强后扫描加脂肪抑制),部分病例增强前加扫冠状面T2WI。2名有经验的放射科医师分别对病变部位、肿块大小、边界、信号、强化及范围作出判断。病变的定位及MRI不同序列中的特征与手术和病理表现行对照研究。结果:臂丛神经的根、干及分支在MRI所有序列中均表现为线状低信号影。36例臂丛神经鞘瘤平均大小为4.9cm(3.0～6.8cm),均表现为沿臂丛神经根生长的肿块。30例表现为边界清楚的纺锤形或长圆形肿块。MRI信号特点:16例表现为均匀的T1WI低或等信号(与肌肉相比),T2WI高信号,增强后中等度强化;20例T1WI呈低信号,T2WI呈不均匀高信号,内见低信号区,所谓的“靶征”,增强后明显强化。所有患者的显微外科手术均遵循肿块内容物的摘除,包膜的剥离与神经的保护相结合的原则。结论:根据臂丛神经鞘瘤的特征性部位和形态学表现以及MRI信号特点,能对本病作出诊断、鉴别诊断及预后判断。该病的典型表现有利于术前作出正确诊断,显微外科手术有利于保护有关神经。     

Gadolinium-DOTA enhanced MR imaging of adnexal tumors

We conducted a retrospective study to assess the potential of contrast enhanced magnetic resonance (MR) imaging in evaluating adnexal tumors. Sixty patients with a total of 77 pelvic lesions underwent MR imaging at 1.5 T and transabdominal ultrasound (US). Precontrast T1- and T2-weighted and Gd-DOTA enhanced T1-weighted MR images were obtained. Diagnoses were proved by surgery in 57 patients. Of the 77 lesions, 54 masses were of ovarian origin, including 12 malignant disorders. Ultrasound demonstrated the lesions in 92%, whereas the sensitivity of unenhanced T2-weighted and postcontrast MR images was 98 and 96%, respectively. Compared to the T2-weighted images, postcontrast MR imaging showed superior overall tumor delineation, assessment of intratumoral architecture, and definition of tumor origin. Contrast enhancement of tumors did not differ significantly between normal ovary and benign and malignant lesions. All modalities were unable to predict malignancy of complex lesions. Based on our study, US remains the screening modality of choice in the evaluation of adnexal tumors. Contrast enhanced MR imaging may be valuable for assessing complex lesions or when the origin of the mass cannot be determined by US. Using contrast enhanced T1-weighted images instead of T2-weighted images may lead to a significant reduction in acquisition time.     

Carcinoma of the cervix: dynamic MR imaging.

Dynamic magnetic resonance (MR) imaging was performed to evaluate eight normal uteri and 29 cervical carcinomas. After rapid injection of gadopentetate dimeglumine, dynamic images were obtained every 30 seconds with the spin-echo (SE) technique in the sagittal plane or the fast low-angle shot (FLASH) technique in the axial plane. In the normal uterus, initial slight enhancement of the junction between endometrium and myometrium was followed by enhancement of the uterine myometrium. Cervical carcinoma was readily distinguished from the cervical stroma and myometrium in the early dynamic phase (30-60 seconds). Tumor-cervix contrast in the early dynamic phase was significantly more marked with the dynamic SE technique than with T2-weighted or contrast material-enhanced T1-weighted imaging (P less than .01). For the evaluation of parametrial invasion, the dynamic FLASH study showed better contrast than did T2-weighted images. Among 18 patients who underwent surgery, accurate assessment of the degree of stromal invasion and tumor size was possible with dynamic MR images in 14 patients (78%), T2-weighted images in 11 (61%), and postcontrast T1-weighted images in seven (39%).     

Magnetic resonance imaging for diagnosis and follow-up of genitourinary, pelvic, and perineal rhabdomyosarcoma.

Magnetic resonance (MR) imaging, ultrasound, and computed tomography (CT) were performed for diagnosis and follow-up of rhabdomyosarcoma (RMS) arising from the genitourinary tract in five children, pelvic musculature in one, and the perineum in three others. MR imaging performed at 1.0 T included the following: spin-density-, T1-, and T2-weighted images in all nine patients; gadopentatate dimeglumine (Gd-DTPA)-enhanced T1-weighted images in five; and short TI inversion recovery (STIR) images in two children. Longitudinal T1-weighted images were of additional help in localizing the primary tumor at diagnosis and detecting local spread. Residual or recurrent disease within the bladder was best detected by spin-density images. Gd-DTPA enhancement improved contrast in two studies, but paramagnetic artifacts obscured intravesical lesions in three other studies. STIR images disclosed pelvic and retroperitoneal lymphadenopathy. MR imaging is recommended as the key method of diagnosis and follow-up of pelvic RMS.     

Delayed MR imaging of hepatocellular carcinoma enhanced by gadobenate dimeglumine (Gd-BOPTA).

The purpose of this study was to determine the efficacy of gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance (MR) imaging for evaluation of hepatocellular carcinoma HCC. MR images were obtained in 14 patients with 31 HCC nodules as a part of a phase III clinical trial. T1- and T2-weighted images were obtained before and after iv administration of 0.1 mmol/kg of Gd-BOPTA. Two blinded readers evaluated pre- and delayed postcontrast images separately for detection of tumor nodules. Quantitative measurements of signal-to-noise (SNR) and tumor/liver contrast-to-noise (CNR) ratios were also performed. A signal/intensity ratio was calculated. Tumor enhancement was correlated with histologic findings. Consensus agreement of precontrast T1- and T2-weighted images revealed 23/31 HCC nodules in 14 patients; postcontrast T1-weighted images demonstrated 24/31 HCC nodules in the same number of patients. Combining both pre- and postcontrast images, 27/31 lesions were detected. Four patients had four well-differentiated HCC nodules detected only on postcontrast images, while three well-differentiated lesions in two patients were only seen on precontrast images. Quantitative evaluation showed an SNR ratio increase in both liver parenchyma and HCC nodules, as well as a significant increase in the absolute CNR ratio on postcontrast T1-weighted gradient-recalled images (P < 0.05). Well-differentiated HCC lesions showed a greater enhancement than poorly differentiated HCC lesions.     

Imaging of tumors of the spine and spinal cord

Imaging of the spine and spinal cord has traditionally been accomplished with plain radiography, myelography, and CT. Recently, MR imaging has become the technique of choice in the assessment of lesions of the spine and spinal cord. MR imaging provides accurate localization of intramedullary, intradural extramedullary, and extradural tumors. Ependymomas and low-grade astrocytomas are the most common intramedullary tumors. MR imaging findings are distinguishable by the delineation and size of the lesion, and the signal intensity on T2-weighted images. Other less common tumors include malignant astrocytomas, hemangioblastomas, and intramedullary metastasis. Numerous foci of high-velocity signal loss are seen in the hemangioblastomas. Metastasis, meningiomas, and schwannomas are the most common intradural extramedullary tumors. Meningiomas are characterized by dural enhancement on postcontrast T1-weighted images. Schwannomas and neurofibromas often erode bony structures and appear to be dumbbell-shaped. Epidural metastasis accounts for the majority of extradural tumors. Primary malignant extradural tumors include lymphomas, chordomas, and so on. The most common primary benign extradural tumor is hemangioma, which often appears to be hyperintense on both T1-weighted and T2-weighted images. Intramedullary non-neoplastic lesions include demyelinating, vascular, and infectious diseases. Diffuse, peripheral, or speckled contrast enhancement, and lack of contrast enhancement may suggest non-neoplastic lesions.     

原发性输尿管癌的诊断:传统尿路造影术与CT、MRI比较(附15例分析)

目的：评价传统尿路造影、ＣＴ与ＭＲＩ在原发性输尿管癌诊断中的价值。材料和方法：本１５年（１６个部位）经手术和病理证实的病例中，１３例（１４次）行静脉肾孟造影（ＩＰＶ），６例（７例）逆行肾盂造影；１例肾穿刺造影；６例ＣＴ检查，其中４例加增强扫描；２例ＭＲＩ检查，先以自旋回波（ＳＥ）序列做轴有冠状面Ｔ１和Ｔ２加仅扫描，再做冠状面磁共振尿路选影（ＭＲＵ）．结果：传统尿路造影共８例９次（６４％）获得术前     

Two cases of metastases to the breast on MR mammography

We report appearance of two cases of metastases to the breast on MR mammography. Metastasis from cervical cancer displayed a hypointense tumor with a central area of high signal intensity on T2-weighted images and rapid annular enhancement with persistent central contrast enhancement. The metastases from rhabdomyosarcoma were characterized by multiple tumors with high signal intensity on T2-weighted images and fast annular contrast enhancement. We show unusual malignant breast lesions for possible identification in dynamic MR mammography. Received: 21 March 2000 Revised: 13 July 2000 Accepted: 19 July 2000     

Magnetic resonance imaging for diagnosis and follow-up of genitourinary,pelvic, and perineal rhabdomyosarcoma

Magnetic resonance (MR) imaging, ultrasound, and computed tomography (CT) were performed for diagnosis and follow-up of rhabdomyosarcoma (RMS) arising from the genitourinary tract in five children, pelvic musculature in one, and the perineum in three others. MR imaging performed at 1.0 T included the following: spin-density-, T1-, and T2-weighted images in all nine patients; gadopentatate dimeglumine (Gd-DTPA)-enhanced T1-weighted images in five; and short TI inversion recovery (STIR) images in two children. Longitudinal T1-weighted images were of additional help in localizing the primary tumor at diagnosis and detecting local spread. Residual or recurrent disease within the bladder was best detected by spin-density images. Gd-DTPA enhancement improved contrast in two studies, but paramagnetic artifacts obscured intravesical lesions in three other studies. STIR images disclosed pelvic and retroperitoneal lymphadenopathy. MR imaging is recommended as the key method of diagnosis and follow-up of pelvic RMS.     

Intradural schwannomas of the spine: MR findings with emphasis on contrast-enhancement characteristics.

Intradural extramedullary schwannomas are nerve sheath neoplasms that consist of focal proliferations of Schwann cells involving a spinal nerve. We reviewed the MR findings in seven patients with pathologically proved intradural schwannomas. The contrast-enhancement characteristics on MR images were determined and compared with the histologic features of the tumor. Six lesions were variably hyperintense on T2-weighted images and one was uniformly hypointense compared with the signal intensity of the spinal cord. Signal on T1-weighted images ranged from hypointense to isointense. All seven tumors showed heterogeneous enhancement; in five, the enhancement involved only the periphery of the lesion. The pattern of enhancement did not correlate with the signal characteristics noted on unenhanced T1- and T2-weighted images. Pathologically, hyaline thickening of vessel walls and cyst formation were prevalent in the peripherally enhancing lesions. However, enhancement did not correlate with the relative proportion of Antoni type A and type B tissue. Recognition of the MR characteristics of intradural extramedullary schwannomas may be helpful in the differential diagnosis of spinal tumors. In particular, peripheral contrast enhancement of an intradural extramedullary tumor on MR images should suggest the diagnosis of schwannoma.     

MR findings in eosinophilic infiltration of the liver

OBJECTIVE: This study describes the findings of magnetic resonance imaging (MRI) of focal eosinophilic infiltration of the liver. METHODS: Contrast-enhanced MR images of 8 patients with focal hepatic eosinophilic infiltration were reviewed retrospectively. We evaluated the signal intensity of focal lesions in T1-weighted and T2-weighted images and the pattern of enhancement in a dynamic contrast study. RESULTS: A total 22 focal hepatic lesions were observed; the lesions were isointense (55%) or hypointense (45%) on T1-weighted images and isointense (14%) or hyperintense (86%) on T2-weighted images. The arterial phase of the contrast study revealed 11 hyperintense lesions (50%). During the portal and delayed phases, 18 (82%) and 17 lesions (77%) were hyperintense, respectively. CONCLUSION: The focal eosinophilic infiltrations showed homogeneous enhancement in the portal and delayed phases in the dynamic contrast MR study. These findings should help to distinguish focal eosinophilic infiltration, especially from metastasis in patients with malignancy.