Contemporary imaging of the renal mass

Contemporary imaging techniques for renal mass evaluation are essential to clinical management and surgical planning. Ultrasonography can be used to distinguish cystic from solid lesions but is less sensitive and accurate in renal mass characterization than computed tomography (CT) and magnetic resonance imaging (MRI). Multiphase CT imaging before and after administration of contrast is the primary imaging modality for characterization and staging of renal lesions. MRI is increasingly used as a problem solving tool. Advanced MRI techniques such as diffusion-weighted imaging and perfusion-weighted imaging are being explored in assessment of renal lesions. These techniques are discussed in this article.     

Advanced Renal Mass Imaging: Diffusion and Perfusion MRI

Computed tomography (CT) is considered the imaging modality of choice in evaluation of renal lesions. The advantages of magnetic resonance imaging (MRI) compared to CT include superior soft tissue contrast, avoidance of ionizing radiation and iodinated contrast media, and the possibility of performing functional and advanced imaging techniques such as diffusion-weighted (DWI) and perfusion–weighted imaging (PWI). Although the traditional role of MRI in the evaluation of renal mass is primarily that of a problem-solving tool, DWI and PWI are expanding the role of MRI in management of renal cell cancers. DWI and PWI have shown considerable promise not only in renal lesion detection and characterization as benign or malignant, but also in assessment of renal cell cancer subtype and nuclear grade. Furthermore, these techniques have the potential to assist with tailoring patient- and disease-specific management by providing surgical planning in patients with localized renal cell cancer and assessing treatment response in patients with advanced renal cell cancer undergoing targeted chemotherapy.     

Clinical value of new rapid nuclear magnetic resonance tomography in preoperative assessment of hypernephroma. A prospective comparative study of CT and MR

The new technique of rapid magnetic resonance imaging (MRI) with a paramagnetic contrast agent provides excellent imaging of the kidneys and their lesions. MR imaging of this anatomical region at short breath holding intervals matches the well-known quality of computed tomography (CT) for the first time. MR and CT studies were performed on 36 patients with proven renal cell carcinoma. Different investigators evaluated the staging of the tumor by means of both techniques in a prospective study. In all patients a radical nephrectomy was performed. Surgical and pathological findings were compared. Though little difference was found in diagnostic value between the two systems, MRI results concerning the T-stage were better. Venous invasion was clearly shown by MRI without the use of contrast medium. Furthermore, sagittal and transaxial images provided a more direct assessment of the extent of the tumor and its demarcation to healthy parenchyma. Thus, MRI is helpful in planning of the surgical approach when organ-sparing excision of renal tumors is to be performed.     

Imaging techniques for the patient with renal cell carcinoma

The imaging of renal cell carcinoma continues to evolve from radiographic tomography to state-of-the-art three-dimensional imagery using computed tomography (CT) or magnetic resonance imaging (MRI). This article reviews the current techniques of imaging the patient with renal cell carcinoma. Careful and accurate imaging of these patients allows for the appropriate diagnosis, treatment planning, and follow-up care. At each point in the care of these patients, imaging plays an important role. In particular, the diagnosis and staging of renal cell carcinoma can be accomplished with CT and MRI, with each modality having strengths and weaknesses that are contrasted. Intraoperative ultrasound is used during laparoscopic or conventional partial nephrectomies, whereas ultrasound, CT, and MRI can be used for guiding ablative technologies. Imaging also plays an important role in the follow-up care of these patients. The particular follow-up care is dependent on the stage and grade of the lesion and the treatment modality used. In summary, this article reviews the current imaging approaches for the diagnosis, staging, treatment, and follow-up care of patients with renal cell carcinoma.     

Magnetic resonance imaging in the staging of renal cell carcinoma

Correct diagnosis and accurate staging of renal cell carcinoma are critical in the evaluation of prognosis and subsequent treatment planning. Between October 1989 and April 1993, 25 patients with histologically proven renal cell carcinoma (RCC) were studied, comparing magnetic resonance imaging (MRI), computerized tomography (CT), operative findings and histopathological results. Two patients with pT3 tumours were understaged by both methods as T2. Three other patients staged as T4 by CT and T3 by MRI were actually pT3. N and V status were accurately detected by both imaging modalities. One patient with biopsy-proven liver metastasis missed by CT was correctly diagnosed by MRI. We conclude that MRI is complementary to CT and is especially helpful in patients with advanced stage and large sized tumours.     

Imaging of multiple myeloma: Current concepts

Medical imaging is of crucial importance for diagnosis and initial staging as well as for differentiation of multiple myeloma (MM) from other monoclonal plasma cell diseases. Conventional radiography represents the reference standard for diagnosis of MM due to its wide availability and low costs despite its known limitations such as low sensitivity, limited specificity and its inability to detect extraosseous lesions. Besides conventional radiography, newer cross-sectional imaging modalities such as whole-body low-dose computed tomography (CT), whole-body magnetic resonance imaging (MRI) and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT are available for the diagnosis of osseous and extraosseous manifestations of MM. Whole-body low-dose CT is used increasingly, replacing conventional radiography at selected centers, due to its higher sensitivity for the detection of osseous lesions and its ability to diagnose extraosseous lesions. The highest sensitivity for both detection of bone marrow disease and extraosseous lesions can be achieved with whole-body MRI and ¹⁸F-FDG PET/CT. According to current evidence, MRI is the most sensitive method for initial staging while ¹⁸F-FDG PET/CT allows monitoring of treatment of MM. There is an evolving role for assessment of treatment response using newer MR imaging techniques. Future studies are needed to further define the exact role of the different imaging modalities for individual risk stratification and therapy monitoring.     

Magnetic resonance imaging of the kidney

Summary At present, MRI of the kidney is considered to be a problem-solving imaging modality that is complementary to CT and ultrasound. The anatomy of the kidney and perirenal space is consistently visualized on MRI, which provides excellent demonstration of the corticomedullary differentiation on T1-weighted images. The indistinctness or obliteration of corticomedullary differentiation is a sensitive but nonspecific finding. The large field of view provided by MRI facilitates the diagnosis of congenital anomalies, but the high cost of the examination precludes its use as a primary imaging method. The use of contrast media has expanded the application of MRI into the detection and characterization of renal masses. However, the greatest value of MRI lies in the staging of renal-cell carcinoma, specifically in cases in which CT and ultrasound findings have proved to be inconclusive. The main advantages provided by MRI in such cases involve the assessment of vascular patency and the evaluation of direct tumor extension.     

Präoperatives Staging von Nierenzellkarzinomen mit Kavazapfen: welches diagnostische Verfahren?

To evaluate whether MRI is usefull in staging renal cell carcinomas with caval thrombus the accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) in staging renal tumors with caval thrombus were preoperatively examined. Tumor staging by CT and MR imaging were correlated with histopathological tumor stadium. In MRI 4 out of 7 thrombi were correctly diagnosed with high accuracy, in CT none. In advanced renal carcinoma MRI with Gadolinium was superior to CT imaging, especially in diagnosing tumor thrombus. Consequently the extent of tumor thrombus may be assessed by MRI which therefore may replace conventional cavography.     

Innovative imaging in urology: fascination and future. Yesterday, today, and tomorrow

In contrast to other countries (e.g., USA) the German urologist routinely utilizes imaging in order to evaluate urological disorders. Ultrasound as a basic tool has acquired importance similar to the physical examination or the patient history. Because of its minimal invasiveness and low cost, it is increasingly utilized as a first-line exam.In correlation with the patient history and laboratory data more invasive imaging studies are performed and in unclear cases or in the preoperative work-up more extensive imaging procedures like computed tomography (CT) or magnetic resonance imaging (MRI) are utilized. Even in emergency situations the urologist is able to guide interventions under ultrasound or conventional X-ray guidance (e.g., percutaneous drainage of dilated kidney), which resulted in a much lower complication rate of the various procedures. In those cases in which ultrasound is technically infeasible or in unclear cases CT and MRI are used as problem-solving procedures and are able to give the correct diagnosis in a large percentage of cases.After a brief historical overview, newer modalities and innovative techniques are explored and presented. Assuming that these innovative approaches lead to more accurate diagnosis and staging of various neoplastic and nonneoplastic conditions, treatment can be performed in earlier stages of diseases and better stage-adapted treatment can be offered to the patients.     

肝内胆管癌影像学诊断

影像技术的快速发展，提高了对肝内胆管癌（ICC）的准确诊断和分期，从而为临床精准治疗ICC提供依据。超声检查是ICC的一线筛查手段，简便，经济，但缺乏特异性。CT及MRI目前仍是诊断ICC的主要影像学方法。MRI具有良好的软组织分辨率和多方位成像等优势，而磁共振胰胆管成像（MRCP）技术，可进一步明确肿瘤与周围胆管关系。MRI对ICC的判别准确性总体优于CT，但CT在显示肝内胆管结石相关的ICC方面较MRI更直观。PET-CT联合CT及MRI，可提高ICC的诊断准确性，并且可弥补了CT及MRI诊断ICC区域淋巴结转移和远处转移的不足。     

Magnetic resonance imaging in a patient with soft tissue sarcoma of the leg

A patient with a high grade malignant fibrous histiocytoma of the leg is presented. Staging studies included a 99mTc diphosphonate bone scan, an arteriogram, a computed tomogram (CT) and a proton (1H) magnetic resonance imaging (MRI) study. By manipulating imaging parameters to enhance contrast between normal and neoplastic tissues, the latter technique more accurately delineated the extent of the soft tissue sarcoma than the other imaging modalities. Although spatial resolution of MRI is inferior to that of CT, it is likely that MRI will provide important information relative to surgical staging and preoperative planning that is not available from current imaging techniques.     

Pathological stage does not alter the prognosis for renal lesions determined to be stage T1 by computerized tomography

PURPOSE: Pathological stage has been the most widely used prognosticator for evaluating surgically managed cases of renal cell carcinoma. Minimally invasive surgical approaches are being increasingly used to treat small masses for which traditionally pathological information is lacking (morcellation) or absent (radio frequency ablation or cryoablation). Preoperative cross-sectional imaging by computerized tomography (CT) or magnetic resonance imaging has been used to stage renal tumors clinically but it can lead to variances with traditional pathological staging systems, particularly with respect to microscopic invasion beyond the renal capsule. In this study we assessed whether radiographically staged clinical T1 lesions that were pathological T1 behave differently than those that were clinical stage T1 and up staged to pT3a. MATERIALS AND METHODS: The records of 296 patients who underwent surgical treatment for renal cell carcinoma at The Johns Hopkins Hospital between 1990 and 1999 were retrospectively reviewed. All patients had undergone preoperative CT or magnetic resonance imaging, which was used to assign a clinical stage and size (largest diameter) to each tumor in accordance with the 1997 TNM staging system. Following surgical resection pathological stage, size and tumor grade were determined. Only the 186 patients with clinical T1 tumors were included in this analysis. RESULTS: Of the 186 patients who were clinically found to have T1 lesions 125 (67%) had pathological T1 and 57 (31%) had pathological T3a lesions. All surgical margins and lymph nodes were negative at surgical resection. Mean tumor size +/- SD was 3.9 +/- 1.5 cm for pT1 lesions and 3.8 +/- 1.5 cm for pT3a lesions. When comparing these pathological groups using Kaplan-Meier analysis, 5-year recurrence-free survival was not statistically different in patients with pT1 and pT3a lesions (90.6 and 97.5%, respectively). CONCLUSIONS: Patients in whom the initial classification of T1 renal cell carcinoma by CT was up graded to T3a on pathological analysis (invasion of fat within Gerota's fascia) showed the same recurrence-free survival rate as patients with pathologically confirmed T1 lesions. Thus, smaller tumors (less than 7 cm) that are up graded to T3a based on capsule invasion behave much like T1 tumors and exact pathological T staging does not appear to impact overall survival.     

Dual-Time <Superscript>18</Superscript>F-FDG PET/CT Imaging in Initial Locoregional Staging of Breast Carcinoma: Comparison with Conventional Imaging and Pathological Prognostic Factors

The aims of this retrospective study were to consider the diagnostic role of dual-time ¹⁸F-fluorodeoxyglucose positron emission tomography and computed tomography (¹⁸F-FDG PET/CT) in detection of breast carcinoma and axillary lymph node (ALN) status and to evaluate the primary tumor ¹⁸F-FDG uptake pattern. Preoperative staging was performed by ¹⁸F-FDG PET/CT in 78 female patients with breast carcinoma. Conventional imaging results were evaluated by breast magnetic resonance imaging (MRI) of 79 lesions in 78 patients, bilateral mammography (MMG) of 40 lesions in 40 patients, and breast ultrasonography (USG) of 47 lesions in 46 patients. The primary tumor detection rate using ¹⁸F-FDG PET/CT was higher than those using MRI, USG, and MMG. The sensitivity and specificity of ¹⁸F-FDG PET/CT scans for detecting multifocality were higher than those of MRI. The specificity of ALN metastasis detection with MRI was higher than that with ¹⁸F-FDG PET/CT, but ¹⁸F-FDG PET/CT had higher sensitivity. Higher ¹⁸F-FDG uptake levels were detected in patients with ALN metastasis, histologic grade 3, estrogen–progesterone-negative receptor status, lymphatic invasion, and moderate to poor prognostic groups. There was no statistical difference for the retention index in categorical pathological parameters except for progesterone-negative status. In conclusion, ¹⁸F-FDG PET/CT scans may be a valuable imaging technique for evaluating primary tumor and axillary status in staging breast carcinoma and ¹⁸F-FDG uptake may be a prognostic factor that indicates aggressive tumor biology and poor prognosis. Dual-time imaging in breast carcinoma staging may not be used for predicting pathological criteria and the aggressiveness of primary lesions.     

A review of applications of MRI in soft tissue and bone tumors

Due to excellent soft tissue contrast and multiplanar imaging capability, MRI is assuming a major role in recognition, staging, and treatment planning of soft tissue and bone tumors. Direct sagittal, coronal, and axial images permit assessment of intraosseous and extraosseous extension of tumors and their relationship to the joints and neurovascular structures, and detection of "skip" lesions. MRI allows improved detection of recurrent tumors in the presence of non-ferromagnetic metallic implants as compared to CT. In the evaluation of soft tissue tumors, MRI is more sensitive than CT and allows differentiation among fat, muscle, tendon, bone, and vascular structures based on signal characteristics. Over a period of 18 months, 100 soft tissue masses and bone tumors were evaluated using MRI. Spin echo sequences with T1 and T2 weighted images were most valuable in differentiating normal and abnormal tissues. Calculated comparative measurements of relaxation times showed no reliable difference between benign and malignant tumors.     

Szintigraphie/Positronenemissionstomographie

Skeletal scintigraphy and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) are established nuclear medicine modalities in the diagnosis of soft tissue tumors. Skeletal scintigraphy scans are performed for detection of osseous infiltration by the primary tumor, of bone metastases and planning of magnetic resonance imaging (MRI). The PET/CT technique has a great potential for assessing tumor grade, for accurate N and M staging, treatment monitoring and in biopsy planning. Recurrent tumors can be detected with high sensitivity, particularly if conventional imaging is impaired by metallic implants. According to current guidelines, if a malignant soft tissue tumor is suspected or proven, PET/CT and PET/MRT should be considered even in children and adolescents.     

Staging and differential diagnosis of renal cell carcinoma: a comparison of magnetic resonance imaging (MRI) and computed tomography (CT)

The usefulness of magnetic resonance imaging (MRI) was compared with that of computed tomography (CT). Twenty-nine patients with renal cell carcinoma, 3 with angiomyolipomas and 1 with renal pelvic cancer, were examined by both MRI and CT. MRI and CT showed similar results in staging cases of renal cell carcinoma. However, MRI may be more sensitive in detecting the venous extension, metastatic adenopathy, and adjacent organ invasion. In predicting the involvement of perinephric fat, however, MRI is only marginally superior to CT. To demonstrate the usefulness of MRI in differentiating renal cell carcinoma from other renal tumors, the density of renal tumor and that of the psoas muscle were determined using a densitiometer, and the percent (%) contrast (the intensity of the renal tumor/the intensity of the psoas muscle X 100) was calculated. In most patients with clear cell type renal carcinoma, the % contrast value in the T1 weighted images was about 100. In the T2 weighted images, the maximum value of the % contrast value was 50 or less in most patients. In one patient with spindle cell type (sarcomatoid type) carcinoma, the % contrast value was 109 in the T1 weighted images, but was 65-85, at most, in the T2 weighted images. In patients with renal angiomyolipomas, the % contrast values were calculated exclusive of the fatty components. The % contrast value of the T1 weighted images was 50 or less in all 3 patients, and that of the T2 weighted images was 50 or more in 2 patients and 21-38 in the others.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pancreatic tumors: role of imaging in the diagnosis, staging, and treatment

Because most patients with pancreatic cancer present with biliary obstruction, percutaneous transhepatic cholangiopancreatography (PTC) or endoscopic retrograde cholangiopancreatography (ERCP) is often performed first to relieve obstruction. Fine needle biopsy (FNA) provides a tissue diagnosis, but is often nondiagnostic due to sampling error. Computed tomography (CT) is the workhorse of oncology, but is poor at defining the nature of pancreatic lesions. Small primary tumors are often not visualized. Fast magnetic resonance imaging (MRI) techniques allowing dynamic imaging after IV gadolinium and new contrast agents allow better characterization of the lesions for patients having contraindications for IV CT contrast agents. Magnetic resonance cholangiopancreatography (MRCP) allows noninvasive visualization of the biliary tree. Endoscopic ultrasonography (EUS) allows evaluation of the detailed regional anatomy with the possibility of FNA. ¹⁸F-Fluorodexoglucose (FDG) is the most common tracer used in positron emission tomography (PET), and most malignant tumors, including pancreatic carcinoma, have increased FDG uptake compared with normal cells. This functional imaging does not replace but is complementary to morphological imaging. FDG PET is particularly helpful: (1) for the diagnosis in patients with suspected pancreatic cancer in whom CT fails to identify a mass, or those in whom FNAs are nondiagnostic; (2) for staging by detecting CT-occult metastases; (3) for detecting recurrence; and (4) for monitoring therapy. Limitations include false-positive inflammatory processes and false-negative carcinoma in patients with diabetes and hyperglycemia, and islet cell tumors.     

Raumforderungen der Niere: CT vs. MRT

Because of progress in imaging, the incidence of renal tumours, especially small lesions, has been rising over the last years. Therefore, imaging must be done to decide how to proceed further. But which is the most effective modality: computed tomography (CT) or magnetic resonance imaging (MRI)? From the technical point of view, the two alternatives appear to be nearly equal. Multidetector CT remains the reference standard for staging and lesion characterisation, whereas MRI is the method of choice for determining caval extension of a tumour thrombus and infiltration of the renal vein. If an accurate diagnosis cannot be specified, the remaining modality should be used complementarily.     

Preoperative assessment of malignant hepatic tumors

Over a 31-month period, 100 patients with malignant hepatic tumors were preoperatively evaluated with three imaging techniques. The results of intravenously enhanced computed tomography (CT) scan, selective hepatic arterial contrast CT, and magnetic resonance imaging (MRI) were compared with operative findings. A total of 227 lesions were identified, with the sensitivity for tumor detection being arteriographically enhanced CT 94% (p less than 0.01), MRI 70%, and CT 66%. This advantage for arteriographically enhanced CT was most marked for lesions less than 1 cm in diameter (82% versus 20% for MRI and 5% for CT; p less than 0.01). Arteriographically enhanced CT was also most sensitive in assessing tumor margins. MRI was clearly superior to arteriographically enhanced CT or CT in detecting vascular involvement (85% versus 30% and 8%, respectively; p less than 0.01). No imaging technique was sensitive in determining extrahepatic involvement. Arteriographically enhanced CT was also best at predicting the operative procedure. The combination of arteriographically enhanced CT and MRI was the best predictor of true disease. We conclude that both arteriographically enhanced CT and MRI should be used for preoperative assessment of hepatic malignancies.     

The role of magnetic resonance imaging for treatment in children with malignant solid tumor

Magnetic resonance imaging (MRI) was performed in 126 children with malignant solid tumor between April 1984 and December 1990. The criteria of tumor visualization, localization, staging, prediction of kidney preserving and monitoring treatment were compared by MRI and CT for 47 children with neuroblastoma, Wilms' tumor, hepatoblastoma, rhabdomyosarcoma and teratoma, MRI and CT were viewed together and an assessment was made as to whether the studies yielded equivalent information or whether one study was superior to the other. 1) The tumor were better visualized in 47% cases by MRI than CT. 2) MRI was superior to CT in 43% cases in evaluating the local spread of tumor. 3) There was little difference between MRI and CT in identification of lymph node metastases. 4) Without requiring the injection of intravenous contrast agents, MRI accurately defined displacement, invasion of renal vessels by neuroblastoma. MRI was excellent in prediction of kidney preserving. 5) MRI was useful to detect bone marrow metastases in neuroblastoma. The best imaging plane for a demonstration of bone marrow involvement was coronal in lower limbs.