Adrenocortical carcinoma: MR imaging appearance with current techniques

The purpose of the study was to define the magnetic resonance (MR) imaging appearance of adrenocortical carcinoma (ACC) with current MR techniques. Eight patients with ACC underwent high-field-strength MR imaging with the following sequences: axial T1-weighted gradient echo, fat-suppressed T1-weighted spin echo, fat-suppressed T2-weighted spin echo, and gadolinium-enhanced T1-weighted gradient echo and fat-suppressed T1-weighted spin echo. Postcontrast images were also acquired in the sagittal (six patients) and coronal (three patients) planes. Out-of-phase gradient-echo images were obtained in two patients. Lesion morphology, signal intensity features, and presence of metastatic disease were retrospectively evaluated. MR imaging features of ACC included internal hemorrhage (seven of eight patients), central necrosis (seven of eight), and peripheral enhancing nodules (seven of eight). Out-of-phase images in two of two patients demonstrated signal loss compared with in-phase images, which may be a common feature of these tumors. Liver metastases were present in four patients. Consistent MR features of ACC are Identified.     

Differential Diagnosis of Benign and Malignant Intraductal Papillary Mucinous Tumors of the Pancreas: MR Cholangiopancreatography and MR Angiography

Objective

To compare the usefulness of magnetic resonance cholangiopancreatography (MRCP) and MR angiography (MRA) in differentiating malignant from benign intraductal papillary mucinous tumors of the pancreas (IPMTs), and to determine the findings which suggest malignancy.

Materials and Methods

During a 6-year period, 46 patients with IPMT underwent MRCP. Morphologically, tumor type was classified as main duct, branch duct, or combined. The diameter of the main pancreatic duct (MPD), the extent of the dilated MPD, and the location and size of the cystic lesion, septum, and communicating channel were assessed. For all types of IPMTs, enhanced mural nodules and portal vein narrowing were evaluated at MRA.

Results

Combined-type IPMTs were more frequently malignant (78%) than benign (42%) (p < 0.05). Compared with benign lesions, malignant lesions were larger, and the caliber of the communicating channel was also larger (p < 0.05). Their dilated MPD was more extensive and of greater diameter (p < 0.05), and the presence of mural nodules was more frequent (p < 0.001).

Conclusion

Combined MRCP and MRA might be useful for the differential diagnosis of malignant and benign IPMTs of the pancreas.     

Rectal carcinoma: Prospective comparison of conventional and gadopentetate dimeglumine enhanced fat-suppressed MR imaging

The purpose of this study is to compare the usefulness of conventional MR imaging and gadopentetate dimeglumine enhanced fat-suppressed MR imaging for the depiction and staging of rectal carcinoma. Thirty-two patients were prospectively evaluated by MR imaging using a 1.5-T unit. Based on the results of a barium study and/or digital examination, a balloon catheter was inserted to the level of the lesion before examination. Both conventional T1- and T2-weighted images and gadopentetate dimeglumine enhanced fat-suppressed T1-weighted images were obtained for all patients. The kappa statistics were performed for the evaluation of interobserver agreement and the McNemar test was performed for the analysis of staging accuracy. When only T1- and T2-weighted images were used, 5 of 32 tumors were not detected and the extent of 18 of 32 tumors were unclear. However, when gadopentetate dimeglumine enhanced fat-suppressed imaging was added, 24 of 32 tumors were well defined and only one tumor was not detected. In determining the depth of invasion, the staging accuracy was 72% for conventional imaging and 68% for all images combined. There was no significant difference between with gadopentetate dimeglumine fat-suppressed imaging and conventional imaging (P > .05). Use of gadopentetate dimeglumine (fat-suppressed imaging) resulted in overestimation of muscular invasion, peri-rectal fat invasion, and adjacent organ invasion in 12 patients, whereas nine patients were overestimated without the use of gadopentetate dimeglumine. In the detection of metastatic lymph nodes, gadopentetate dimeglumine enhanced fat-suppressed imaging also was not useful. Tumor detection was excellent using gadopentetate dimeglumine enhanced fat-suppressed images. However, the accuracy of staging was not improved by obtaining such images.     

Multilocular cystic nephroma: MR imaging appearance with current techniques,including gadolinium enhancement

The purpose of the study was to define the MRI appearance of multilocular cystic nephroma (MLCN), using current MR techniques, including gadolinium (Gd)-enhanced sequences. Seven patients with MLCN underwent MR imaging with the following sequences: T1-weighted spin echo with fat suppression (TIFS, five patients), T1-weighted spoiled gradient echo (SGE, seven patients), T2-weighted fast spin echo (two patients), and Gd-enhanced TIFS (seven patients) and SGE (seven patients). MLCN was histologically proven by resection of the mass in six patients and by observation of typical imaging features with stability in appearance over a 6-month period in one patient. Lesion morphology and signal intensity (SI) features were retrospectively evaluated. MRI features of MLCN included a solitary cystic lesion with thin internal septations in six patients and a cluster of closely grouped cysts similar in size in one patient. Individual cystic spaces demonstrated SI, varying from low to high on T1-weighted images in three patients and demonstrated low-to-intermediate SI in four patients. Herniation of the lesions into the renal collecting system and thin enhancing septa were demonstrated in all patients. A complex cystic renal lesion with enhancing septa and herniation into the renal collecting system are the characteristic MR findings of MLCN. The direct multiplanar capability of MR may optimally show the relationship of MLCN to the renal pelvis and, thus, facilitate correct diagnosis.     

Pancreatic masses with inconclusive findings on spiral CT: Is there a role for MRI?

This prospective study evaluates the ability of MRI using T1-weighted fat-suppressed spin-echo (T1FS) and dynamic gadolinium chelate (Gd) enhanced spoiled-gradient echo (SGE) to detect the presence of pancreatic tumor in patients in whom spiral CT findings are inconclusive. Sixteen consecutive patients who underwent spiral CT and had findings that were considered inconclusive for pancreatic tumor underwent MR within 2 weeks of CT. Spiral CT and MR images were interpreted in a prospective fashion by separate individual investigators blinded to the results of the other imaging modality. CT was performed on a spiral CT scanner. MRI was performed on a 1.5-T MR machine. Imaging sequences included T1FS pre-Gd and post-Gd and SGE pre-Gd and immediately post-Gd. Data were analyzed using receiver operating characteristic (ROC) analysis. Confirmation was obtained by pancreatic biopsy (n = 4), surgical resection (n = 1), and clinical imaging (n = 4) or clinical follow-up (n = 7). MRI was superior to spiral CT (P = .027) in this selected patient group at detecting or excluding pancreatic tumor by ROC analysis, with areas under the curve of .982 and .764, respectively, which was significant (P = .041). The greatest advantage of MRI was in patients in whom spiral CT demonstrated enlargement of the pancreatic head without clear definition of tumor, which was significant (P = .033). In 10 patients with this CT appearance, MRI demonstrated a high confidence for presence of tumor in four and a high confidence of absence in six. Association of imaging findings with patient diagnosis was significant for MRI (P = .001) but not significant for CT (P = .148). The results of our study suggest that MRI may add significant diagnostic information in patients in whom spiral CT is inconclusive for the presence of pancreatic tumor. The greatest advantage of MRI was in the evaluation of patients in whom spiral CT findings revealed an indeterminate enlarged pancreatic head.     

Granulomatous prostatitis: a pitfall in MR imaging of prostatic carcinoma

Granulomatous prostatitis is an uncommon disease that can prostatic carcinoma on both digital rectal examination and transrectal ultrasound. Four patients who underwent magnetic resonance imaging of the prostate had a histological diagnosis of graanulomatous prostatitis; three of them had recent urinary tract infections. The other patient had an associated midline prostatic cyst and a focus of malignancy. T1-and T2-weighted spin-echo images were obtained in all cases. Peripheral zone lesions of decreased signal intensity, suggestive of carcinoma,were found in all four patients on T2-weighted images. Granulomatous prostatitis should be considered in the differential diagnosis of low signal intensity areas with prostatic magnetic resonance imaging. Correspondence to; P.A. Gevenois     

Evaluation of focal pancreatic masses: comparison of mangafodipir-enhanced MR imaging and contrast-enhanced helical CT

The detection and characterization of pancreatic tumors as well as the reliable staging of pancreatic cancer are important tasks for radiologic evaluation. Contrast-enhanced helical CT has been the standard modality for pancreatic imaging in many institutions, but MR imaging has gained a considerable role in the evaluation of patients with equivocal CT findings. Recently, the first organ-specific MR contrast agent targeted to the liver and pancreas, mangafodipir trisodium, has been registered in the European Union (EU) for use in MR imaging of the pancreas. This paper reviews technical considerations and characteristic imaging findings of mangafodipir-enhanced MR imaging in the assessment of focal pancreatic lesions. Contrast-enhanced MRI has proven to be very helpful in the detection of small tumors or the identification of tumor-simulating lesions in patients with equivocal CT findings. Mangafodopir may improve the staging of pancreatic cancer by increasing the sensitivity of MRI in the detection of liver metastases. This review summarizes the potential of contrast-enhanced MRI and the limitations compared with contrast-enhanced helical CT. Electronic Publication     

Small bowel neoplastic disease: Demonstration by MRI

This study demonstrates the appearance of small bowel tumors on MR images. Sixteen patients with tumors involving small bowel were studied by MRI. All tumors were proven with histopathology. Eleven patients had primary tumors of the small bowel, which included the following: four carcinoid tumors, three adenocarcinomas, two lymphomas, one leiomyosarcoma, and one leiomyoma. Five patients had recurrent or metastatic disease to small bowel: two patients had colon cancer, one patient had pancreatic cancer, one patient had uterine leiomyosarcoma, and one patient had chloroma (leukemia). MR examination included breath-hold T1-weighted spoiled gradient echo (all patients), immediate postgadolinium-spoiled gradient echo (10 patients), and 2 to 4 minutes postgadolinium T1-weighted, fat-suppressed images (all patients). Tumor size, local extent, signal intensity, and enhancement features of tumor and adjacent tissue were determined. Tumor ranged in diameter from 1 to 9 cm (mean, 4.0 cm). Tumors had similar signal intensity to normal small bowel on precontrast images. Fourteen malignant tumors showed heterogeneous enhancement greater than adjacent bowel on gadolinium-enhanced images. Tumor local extent was best shown on precontrast-spoiled gradient-echo images and postgadolinium T1-weighted fat-suppressed images. Image quality was most consistent on breath-hold images. The results of this study show that small bowel tumors are demonstrable on MR images. Precontrast breath-hold T1-weighted spoiled gradient-echo images and gadolinium-enhanced fat suppressed images demonstrate tumor extent most reliably.     

Pancreatic signal intensity on Tl- weighted fat saturation MR images: Clinical correlation

To determine whether signal intensity (SI) of the pancreas that was less than that of liver on Tl- weighted fat-suppressed (T1FS) magnetic resonance (MR) images could be used to help predict the presence of pancreatic disease, three blinded independent observers graded pancreatic SI relative to liver and/or renal cortex in 89 patients on T1PS images. Results were correlated with patient age and diagnosis. Among the 47 patients with a clinically normal pancreas, pancreatic SI was higher than that of liver in 42 and equal to that of liver in the rest, none of whom had evidence of fatty pancreas. These five patients had a mean age of 71 years, compared with 55 years for patients whose pancreas was more intense than liver (P=.02). Of the 42 patients with a clinically abnormal pancreas, only eight had pancreatic SI higher than that of liver. The positive predictive value for normal pancreas of an SI higher than that of liver was 84% and the positive predictive value for abnormal pancreas of an SI less than or equal to that of liver was 88%, with an overall accuracy of 86%. If normal pancreatic SI is defined as higher than that of liver for patients younger than 60 years and as equal to or higher than that of liver for patients older than 60 years, the positive predictive value of normal SI becomes 76%, the positive predictive value of decreased SI becomes 100%, and the overall accuracy becomes 83%. Pancreatic SI less than that of liver correlates highly with pancreatic disease, especially in younger patients. Mildly decreased pancreatic SI, equal to that of nondiseased liver, is common in older persons without clinically apparent pancreatic disease.     

Abdominal MR: liver and pancreas

Following the introduction of rapid, high-quality scan techniques and the development of new, tissue-specific contrast agents, the applications of MRI for abdominal imaging are experiencing unprecedented growth. This article examines the current status of liver and pancreatic MRI, highlighting technical and methodological approach, use of contrast agents, and main clinical applications. The MRI technique appears to be the ideal diagnostic tool for detection and characterization of benign and malignant liver neoplasms, and for evaluating tumor response after nonsurgical treatments. Dynamic imaging after bolus injection of a gadolinium chelate is currently a fundamental component of an MRI examination of the liver in many instances. Optimal dynamic scanning depends on the use of a multisection spoiled gradient-echo technique that allows one to image the entire region of interest during a single suspended respiration. Images are obtained during four phases relative to the injection of the contrast agent: precontrast, arterial (pre-sinusoidal), portal (sinusoidal), and delayed (extracellular) phase. Liver-specific contrast agents, including hepatobiliary agents and reticuloendothelial system-targeted iron oxide particles, however, may offer advantages over gadolinium chelates in some clinical settings. Computed tomography is still preferred to MRI for imaging the pancreas. However, state-of-the-art MRI may currently be at least as accurate as spiral CT for depiction of inflammatory and neoplastic pancreatic diseases. Moreover, MRI has the advantage of allowing simultaneous investigation of the biliary tree, owing to cholangiopancreatography techniques. Hence, a comprehensive assessment of most pancreatic diseases can be achieved with a single examination.     

Intraorbital granular cell tumor: MR findings

A 68-year-old man presented with an intraocuiar mass. The histopathologic study showed a granular-cell tumor. The MR features of this rare tumor and its possible differential diagnosis are discussed.     

MR imaging of edema accompanying benign and malignant bone tumors

To evaluate the incidence, quantity, and presentation of intra- and extraosseous edema accompanying benign and malignant primary bone lesions, the magnetic resonance (MR) studies of 63 consecutive patients with histologically proven primary bone tumors were reviewed. MR scans were assessed for the presence and quantity of marrow and soft tissue edema and correlated with peroperative findings, resected specimens and follow-up data. The signal intensity and enhancement of tumor and edema prior to and after intravenous administration (if any) of gadolinium-labled diethylene triamine pentaacetate (Gd-DTPA) was analyzed. Marrow edema was encountered adjacent to 8 of 39 malignant tumors and 14 of 24 benign lesions. Soft tissue edema was found accompanying 28 of 39 malignancies and 10 of 24 benign disorders. On unenhanced T1-weighted MR images tumor and edema were difficult to differentiate. Tumor inhomogeneity made this differentiation easier on T2-weighted sequences. In 36 patients the contrast medium Gd-DTPA was used. Edema was present in 27 of these patients and the respective enhancement of tumor and edema could be compared. Edema always enhanced homogeneously, and in most cases it enhanced to a similar degree as or more than tumor. Marrow and, more specifically, soft tissue edema is a frequent finding adjacent to primary bone tumors. The mere presence and quantity of marrow and soft tissue edema are unreliable indicators of the biologic potential of a lesion. Unenhanced MR scans cannot always differentiate between tumor and edema, but the administration of Gd-DTPA is of assistance in differentiating tumor from edema. Awareness of marrow and/or soft tissue edema adjacent to bone lesions is of importance because edema can be a pitfall in the diagnostic work-up and staging prior to biopsy or surgery.     

Dynamic gadopentetate dimeglumine-enhanced MR imaging of hepatocellular carcinoma

Nineteen patients with 28 histologically proven hepatocellular carcinomas (HCCs) were examined using T1- and T2-weighted spin-echo sequences and dynamic gadopentetate dimeglumine-enhanced magnetic resonance imaging (MRI) performed by fast T1-weighted gradient-echo sequence (100/5/80°) which was performed before and repeatedly (12 sets of images) after intravenous bolus injection of gadopentetate dimeglumine (Gd-DTPA) over a period of 10 min. Enhancement of HCC was heterogeneous in 24 lesions (85.7%). Intra-lesional non-enhancing areas were seen in 18 cases (64%). A late-enhancing pseudocapsule was seen in 12 lesions (42.9%). In addition, two groups were distinguished in the examined HCCs: 16 lesions (57.1%) showed stronger enhancement compared to liver parenchyma with maximum positive lesion-to-liver contrast on the 15-s images, while 12 lesions (42.9%) had an enhancement less than normal liver with a maximum negative contrast on the 15-s images. We conclude that the morphologic features most frequently encountered in HCC on dynamic Gd-DTPA-enhanced MRI are inhomogeneity of enhancement, intra-lesional non-enhancing areas, and relatively late enhancement of a pseudocapsule. Taking the degree of enhancement to be representative of the degree of vascularity, we also conclude that HCC can appear either hypervascular or hypovascular in the early phase of the dynamic study. Correspondence to: B. Hamm     

Endorectal surface coil MR imaging of prostatic carcinoma with the inversion-recovery sequence

The value of inversion-recovery (IR) sequences in the diagnosis and staging of prostatic carcinoma with magnetic resonance (MR) imaging was studied. Twenty-six patients with carcinoma of the prostate were imaged at 1.5 T with an endorectal surface coil and with a variety of IR sequences and a set of spin-echo (SE) sequences for comparison. Ex vivo prostate specimens were imaged again at the same field strength. The two images were correlated with histologic sections. Cancer was identified with MR imaging in 96% of patients. Of the tumors more than 4 mm in diameter, 87% were identified on T2-weighted SE images, whereas only 26% were identified on IR images. However, IR images may be more useful in local staging of carcinoma. Gross capsular infiltration was present in only two patients; however, it was detectable (and excluded in five other patients) by means of IR images. It was not detectable on SE images. The high quality of images obtained with the endorectal coil was confirmed. The authors conclude that addition of the IR sequence to MR imaging with the endorectal coil may improve the usefulness of this examination.     

Malignant lesions of the liver with high signal intensity on T1-Weighted MR images

Our purpose was to identify the histologic types of malignant liver lesions with high signal intensity (SI) on T1-weighted images and to describe the MR imaging features. Thirteen patients with malignant liver lesions high in SI on T1-weighted images were studied with a 1.5-T MR imager using pre- and serial postcontrast spoiled gradient-echo (SGE) sequences (all patients), T2-weighted fat-suppressed spin-echo sequences (all patients), precontrast T1-weighted fat-suppressed spin-echo sequences (five studies in five patients), and precontrast out-of-phase SGE sequences (seven studies in six patients). Images were reviewed retrospectively to determine number of lesions; lesion size; SI of lesions on T1-weighted, T2-weighted, and fat-attenuated T1-weighted images; distribution of high SI in lesions on T1-weighted images; and tumor enhancement pattern. Seven patients had multiple tumors high in SI on T1-weighted images and six patients had solitary tumors. Seventy-two lesions were less than 1.5 cm in diameter and 35 lesions were more than 1.5 cm in diameter. Nine patients had solid malignant lesions and four patients had cystic malignant lesions. All tumors more than 1.5 cm in diameter were heterogeneously high in SI on T1-weighted images, and all tumors less than 1.5 cm were completely homogeneous or homogeneous with a small central hypointense focus. All tumors were more conspicuous on T1-weighted fat-attenuated images, both on excitation spoiled fat-suppressed spin-echo or on out-of-phase SGE images with the exception of one fat-containing hepatocellular carcinoma (HCC). In one patient with melanoma metastases and one patient with multiple myeloma nodules, appreciably more lesions were detected on out-of-phase SGE images. Causes of hyperintensity were considered to be either fat, melanin, central hemorrhage, or high protein content, all of which may be seen in a variety of tumors. Fat-attenuation techniques are helpful in the detection of these lesions.     

Acinar cell carcinoma of the pancreas ultrasonography and computed tomography findings

The radiologic findings in two cases of acinar cell carcinoma of the pancreas are described. Sonographic findings were a midrange echogenic mass with heterogeneity, containing some small- and medium-sized low echogenic areas suggesting necrosis. Ultrasonic through-transmission was good. Computed tomography findings were a well-defined, hypodense, large mass having an enhancing, thin capsule. There were multiple small- and medium-sized irregular low-density areas suggesting necrosis. Small punctate calcific foci were present in one case. With these characteristics, acinar cell carcinoma can be distinguished from the locally invasive common adenocarcinoma of the pancreas, but the differentiation from some other less common pancreatic tumors remains difficult.     

MR imaging of Hippel-Lindau disease: value of gadopentetate dimeglumine.

Hippel-Lindau disease is an autosomal dominant disorder characterized by tumors of the central nervous system and abdominal viscera. Frequent multisystem radiologic evaluation of persons at risk is desirable. Twenty-seven patients with Hippel-Lindau disease or a family history of the disease were examined with both unenhanced and gadopentetate dimeglumine-enhanced magnetic resonance (MR) imaging to study the usefulness of the contrast medium in the evaluation of these patients. The MR studies were correlated with computed tomographic (CT) scans in seven patients and cerebral angiograms in five. Twelve patients had hemangioblastomas in the brain, and eight of these patients also had spinal cord lesions (most were multiple), well demonstrated with gadopentetate dimeglumine. Contrast-enhanced MR imaging enabled detection of more central nervous system lesions and provided better delineation than unenhanced MR imaging, CT, or angiography. In addition, four patients with multiple renal cysts seen on CT scans and unenhanced MR images had enhancing lesions that were later proved to be renal cell carcinoma at angiography and/or surgery. Four patients had cystic lesions in the pancreas that did not enhance and were later proved to be pancreatic cysts. The authors conclude that gadopentetate dimeglumine-enhanced MR imaging appears to be a useful method for evaluating and following up patients with Hippel-Lindau disease.     

Muscle edema in musculoskeletal tumors: MR imaging characteristics and clinical significance.

To determine the frequency and clinical significance of tumor-associated muscle edema, magnetic resonance (MR) imaging findings in 46 consecutive patients with benign or malignant musculoskeletal lesions were reviewed. Increased muscle signal intensity on T2-weighted, STIR (short-inversion-time inversion-recovery), and gadopentetate dimeglumine-enhanced T1-weighted images was present in 41 cases, with the clearest delineation of tumor margins seen on T2-weighted images. Typical peri/paratumoral edema (PTE) was present in equal proportions of malignant (25 of 37) and benign lesions (six of nine). Massive edema involving the entirety of at least one contiguous muscle--to the authors' knowledge, a previously undescribed finding--was identified on MR images of eight malignant and two benign lesions (22% of both groups). All cases of massive edema had a substantial soft-tissue component and involved muscles disrupted by tumor at the point of attachment to bone. Malignant tumors associated with massive edema were larger than those with typical or no PTE, showed a poorer response to initial chemotherapy, and had a higher frequency of metastases at diagnosis. Thus, the presence of massive muscle edema appears to be an ominous clinical finding in patients with malignant musculoskeletal lesions.     

Ampulla of Vater: comprehensive anatomy, MR imaging of pathologic conditions, and correlation with endoscopy

Endoscopic retrograde cholangiopancreaticography with or without an endoscopic biopsy is the method for making a definitive diagnosis of disease in or around the ampulla of Vater. However, the endoscopic findings of neoplastic and non-neoplastic conditions involving the perimapullary area may be similar and an endoscopic assessment is not entirely reliable for diagnosis. Recent MR and MRCP can allow the detection of lesions in a small complex structure such as the ampulla of Vater, and distinguish between an ampullary from periampullary lesion. This article reviews the normal anatomy of the ampulla of Vater, describes the role of MR in the detection and characterization of the lesion in or around the ampulla of Vater, and attempts to correlate them with ERCP.