Magnetic resonance imaging appearance of metastatic Merkel cell carcinoma to the sacrum and epidural space

Merkel cell carcinoma (MCC) is a rare malignant tumor of the skin and often is diagnosed histologically as lymphoma, melanoma and even metastatic small cell carcinoma of the lung (SCCL). Classified as a neuroendocrine tumor, clinically it originates in the head and neck region and may present with metastatic disease at the time of presentation [1]. Osseous involvement in the past has been described to involve regional facial bones only. We present the first reported MRI findings of distant osseous metastasis from a Merkel cell carcinoma to the lumbosacral spine with associated soft tissue and epidural involvement. Appropriate treatment and patient survival depend on prompt diagnostic imaging for establishment of metastatic disease. Previous reports have advocated CT for diagnosis and staging of distant metastases [2,3]. When spinal involvement is suspected, MRI may be a more suitable modality for assessment of the epidural space and appropriate staging and follow-up in such cases.     

In vivo proton magnetic resonance spectroscopy (MRS) and single photon emission computerized tomography (SPECT) in systemic lupus erythematosus (SLE)

Neuropsychiatric involvement in SLE (NP-SLE) may not be picked up by routine neuroimaging procedures like computerized tomography (CT) or magnetic resonance imaging (MRI). We prospectively studied the role of single photon emission computerized tomography (SPECT) and magnetic resonance spectroscopy (MRS) in detection of NP-SLE in 20 patients with lupus (10 with clinical NP involvement and 10 without) and 9 healthy controls. MRI abnormalities were seen in 5/10 patients with NP-SLE while the MRI was normal in all the lupus patients without clinical NP involvement. Perfusion defects on SPECT were seen in as many as 8/10 patients with NP-SLE while only 1/10 lupus patients without clinical NP involvement and none of the healthy controls demonstrated perfusion defects. MRS revealed abnormal metabolite ratios in all patients with NP-SLE and as many as 8 lupus patients without clinical NP features. Normal metabolite ratios were observed in healthy controls. SPECT and MRS can help detect changes not evident on MRI and may serve as useful supplements to existing neuroimaging techniques in the diagnosis of NP-SLE. The precise significance of alterations in regional cerebral blood flow on SPECT and neurometabolite ratios on MRS needs larger, longitudinal studies.     

Congenitally corrected transposition of the great arteries (L-TGA) with situs inversus totalis in adulthood: findings with magnetic resonance imaging

Diagnosis of congenitally corrected transposition of the great arteries (L-TGA) with situs inversus totalis in two adult patients was made by magnetic resonance imaging (MRI). Visualization of the complete anatomy and quantification of ventricular function was possible. Relevant concomitant disease such as perimembraneous ventricular septal defect, atrial secundum septal defect, tricuspid regurgitation, valvular pulmonic stenosis, and pulmonary artery dilatation were clearly depicted by MRI using standard spin-echo and gradient-echo techniques. Findings were confirmed by cardiac catheterization in both patients. In this rare and complex congenital cardiac anomaly, MRI is an excellent imaging modality as echocardiography may be difficult to interpret due to restricted imaging windows. MRI may help in the decision about the necessity to undergo further invasive evaluation and may help to make cardiac catheterization a straightforward procedure.     

Magnetic resonance imaging as an adjunct to sonography in the evaluation of the female pelvis

Magnetic resonance imaging (MRI) of the pelvis is generally considered to be most beneficial in those cases where the pelvic sonogram is limited or equivocal. All cases that underwent both sonographic and MRI examinations at our institution for the evaluation of the female pelvis in the past two years were retrospectively reviewed. We reviewed the sonographic and MRI reports and the subsequent clinical management in the 41 cases that had both studies to assess whether MRI contributed to the clinical management decision. Both studies were interpreted independently based upon the known clinical and laboratory data available at the time. MRI was obtained in 21 cases because the sonogram was suboptimal or inconclusive. In the other 20 cases it was obtained for additional information, even though the sonogram was diagnostic. Of the 21 inconclusive sonographic studies, MRI established or clarified the diagnosis in all cases. Of the 20 studies where MRI was obtained for additional information, MRI added useful data that helped contribute to the clinical management of 11 patients. MRI is an important adjunct to pelvic sonography. It established, clarified, or added significant data in 78% of cases.     

MRI of female uterine and juxta-uterine masses: clinical application in 25 patients.

The clinical utility of magnetic resonance imaging (MRI) in the diagnosis of gynecologic masses was evaluated in 25 patients. In each patient the final pathologic diagnosis was semiquantitatively correlated with the diagnostic impressions from pelvic examination, ultrasound and MRI. There were 9 uterine, 11 ovarian and 5 nonovarian pelvic masses. Pelvic examination correlation with final diagnosis was 26%, consistent with the literature. Ultrasound fared surprisingly poorly, with only 44% correlation. MRI showed an 87% correlation with the final diagnosis. MRI was able to accurately identify masses, discriminate adnexal masses from fluid-filled bowel, identify dermoids, and in one case obviated surgery in a pregnant patient. MRI provided significant clinical management information with greater accuracy than did ultrasound or pelvic examination.     

MR imaging of degenerative disorders of brainstem and cerebellum

In pathologies such as progressive ataxias, clinical criteria are often not enough to provide the correct diagnosis. Therefore, we studied by means of MRI 30 normal volunteers and 19 patients affected by different progressive ataxias, diagnosed by typical standards. On all the subjects measurements were performed in order to identify normal and pathological ranges. Our experience confirms that typical involvement can be detected in the different kinds of progressive ataxias. Peculiar compromissions were found in spinocerebellar diseases, able to differentiate them from the forms mostly involving the cerebellum and brainstem. The differentiation between typical Friedreich and non-Friedreich diseases can also be suggested in most cases.     

Gadolinium- and superparamagnetic-iron-oxide-enhanced MR findings of intrapancreatic accessory spleen in five patients

Purpose

The purposes of this study were to describe dynamic gadolinium-enhanced magnetic resonance imaging (MRI) findings of intrapancreatic accessory spleen(s) (IPAS) in five patients and to show how superparamagnetic iron oxide (SPIO) enhancement can be used for definite characterization in two cases.

Materials and Methods

An MRI database was searched for patients who had pancreatic tail lesions with imaging features compatible with IPAS between June 2005 and July 2007. Five (four male, one female) patients (age: mean±S.D., 58±9.8 years; range, 50–75 years) were identified. All patients were examined with standard gadolinium-enhanced MRI protocol. Additionally, two patients were examined with SPIO-enhanced MRI protocol. All MRI examinations were retrospectively and blindly evaluated by two radiologists for the predetermined findings, and their final diagnoses were noted.

Results

One pancreatic tail lesion was detected in each patient. All of these lesions were single, focal, well-marginated and located within 3 cm of the distal tail of the pancreas. The mean size (mean±S.D.) of the lesions was (2.02±0.64)×(1.72±0.42) cm², and all lesions had a rounded morphology. The signal intensity of all lesions was similar to that of the spleen on all sequences, including precontrast, postgadolinium and post-SPIO sequences. The reviewers confidently diagnosed IPAS in two patients who had SPIO-enhanced MRI. In the remaining three patients, the reviewers favored the diagnosis of IPAS based on the findings of standard gadolinium-enhanced MRI; however, they could not definitively exclude the other differential diagnoses.

Conclusion

The discovery of a well-marginated, rounded mass in the distal aspect of the tail of the pancreas with signal intensity features of the spleen on all precontrast and postgadolinium sequences suggests the diagnosis of IPAS. However, SPIO-enhanced MRI can be used to characterize the lesion and to establish the definite diagnosis of IPAS in case of clinical doubt.     

Hemorrhagic cerebral metastases from thyroid cancer on T2*-weighted gradient echo MRI

We report a case of multiple hemorrhagic cerebral metastases from papillary thyroid cancer, with reference to T(2)*-weighted gradient echo (GRE) magnetic resonance imaging (MRI). Small metastatic nodules were recognized as round nodules with signal loss on T(2)*-weighted GRE MRI, and were more pronounced compared with other sequences. Lesions were later confirmed as hemorrhagic on T(1)- and T(2)-weighted MRI. T(2)*-weighted GRE MRI was a sensitive tool for early detection of metastases displaying hemorrhagic changes.     

The diagnostic role of gadolinium enhanced MRI in distinguishing between acute medullary bone infarct and osteomyelitis

The objective of the study was to evaluate the diagnostic utility of contrast enhanced magnetic resonance imaging (MRI) for distinguishing between acute medullary bone infarct and osteomyelitis. There were 11 patients (age 6-34 years) presented to our institution between December 1994 and February 1998 with a clinical differential diagnosis of acute bone infarct versus osteomyelitis and inconclusive radiographs were imaged using MRI. All but one received i.v. gadolinium. Nine of the patients had homozygous Sickle Cell disease (SCD) and two had Systemic Lupus Erythematosus (SLE), the latter requiring chronic methylprednisolone. Osteomyelitis was confirmed either by biopsy alone or by the combination of Gallium(67) scan in conjunction with positive blood cultures and clinical resolution following antibiotics. Infarcts without osteomyelitis were confirmed either by biopsy or resolution of symptoms without antibiotic therapy. All patients had at least six months clinical follow-up. The results found that seven of nine patients with SCD had acute infarct only. One patient with SCD had osteomyelitis only. Three patients (two SLE and one SCD) had both acute-on-chronic infarcts and superimposed osteomyelitis, one with an adjacent soft tissue abscess. Accurate distinction between infarct and osteomyelitis was impossible for one patient with SLE who did not receive contrast. All other cases were correctly diagnosed prospectively based on distinct patterns of MRI contrast enhancement. In all adult patients, acute infarcts demonstrated thin, linear rim enhancement on MRI while osteomyelitis revealed more geographic and irregular marrow enhancement. Two of four cases of osteomyelitis also demonstrated subtle cortical defects with abnormal signal traversing marrow and soft tissue. The single pediatric patient demonstrated elongated, serpiginous central medullary enhancement with periostitis. We concluded that the pattern of MR contrast enhancement may allow accurate distinction between acute infarct and osteomyelitis, or recognition of osteomyelitis superimposed on bone infarction.     

Ultrafast MRI of the fetus: an increasingly important tool in prenatal diagnosis of congenital anomalies

Objective

To demonstrate the additional utility of ultrafast magnetic resonance imaging (MRI) of the fetus in the evaluation of sonographically detected or equivocal fetal congenital anomalies.

Material and Methods

Twenty five pregnant women with ultrasound detected fetal congenital anomalies underwent ultrafast fetal MRI.

Results

MRI findings altered the diagnosis of two cases of giant arachnoid cyst and sizable interhemispheric cyst associated with agenesis of the corpus callosum. MRI added additional findings of occult spinal diastematomyelia in two out of four cases of Chiari/meningocele malformation. MRI revealed impaired sulcation and unilateral cleft palate in suspected case of Walker-Warburg syndrome. In the remaining 18 cases MRI confirmed the diagnosis of Meckel–Gruber syndrome in three cases, hydronephrosis in six cases, cerebral ventriculomegaly in five cases, isolated omphalocele in three cases and findings suggestive of aneuploidy in the last case.

Conclusion

Ultrasound is the screening method of choice for evaluation of the fetus. Ultrafast MRI is a complementary adjunctive modality with excellent tissue contrast that can image the fetus in multiple planes and add information in sonographically detected or equivocal congenital anomalies that may be significant to establish definitive accurate diagnosis and hence adequate management and counseling.     

Cardiac calcifications: difficult MRI diagnosis

Magnetic resonance imaging (MRI) and computed tomography (CT) were performed in 40 patients with a variety of cardiovascular diseases. These imaging modalities were compared to investigate their relative value in the assessment of cardiovascular diseases. Of these 40 patients, 7 were found by CT to have detectable cardiovascular calcifications. These patients included one calcified mitral stenosis, one calcified coronary artery, one calcified type B aortic dissection, two calcified myocardial infarctions, and two patients with calcific pericarditis. In several cases, MRI was misleading because of difficulty in detecting calcifications. We present a series of cases illustrating a limitation of MRI in identifying diagnostically and clinically important cardiovascular calcifications.     

MRI-guided biopsy in inflammatory myopathy: Initial results

The purpose of this report is to describe our initial experience with techniques employing magnetic resonance imaging (MRI) to guide the choice of muscle to be biopsied in patients suspected of having inflammatory myopathy. Five patients with a clinical diagnosis of inflammatory myopathy (IM) were studied. Four were imaged prior to biopsy. Four had repeated examinations, either immediately following biopsy or to evaluate disease progression. Use of MRI to localize muscle lesions was associated with abnormal pathologic findings in all cases, including histopathologic demonstration of lymphocyte infiltration in three cases of idiopathic polymyositis; nonspecific myopathic changes were seen in one patient with probable dermatomyositis and in one patient with chronic inflammatory polyneuropathy and high serum creatine kinase levels (>45,000 IU/ml). The precise location of the area sampled by biopsy was visible in only one of four postbiopsy images. MRI shows promise in identifying pathologic muscle in patients suspected of having one of the inflammatory myopathies; however, further refinement of localization techniques may be needed to optimize histopathologic diagnoses.     

Generalized Kohonen's competitive learning algorithms for ophthalmological MR image segmentation

Kohonen's self-organizing map is a two-layer feedforward competitive learning network. It has been used as a competitive learning clustering algorithm. In this paper, we generalize Kohonen's competitive learning (KCL) algorithm with fuzzy and fuzzy-soft types called fuzzy KCL (FKCL) and fuzzy-soft KCL (FSKCL). These generalized KCL algorithms fuse the competitive learning with soft competition and fuzzy c-means (FCM) membership functions. We then apply these generalized KCLs to MRI and MRA ophthalmological segmentations. These KCL-based MRI segmentation techniques are useful in reducing medical image noise effects using a learning mechanism. They may be particularly helpful in clinical diagnosis. Two real cases with MR image data recommended by an ophthalmologist are examined. First case is a patient with Retinoblastoma in her left eye, an inborn malignant neoplasm of the retina frequently metastasis beyond the lacrimal cribrosa. The second case is a patient with complete left side oculomotor palsy immediately after a motor vehicle accident. Her brain MRI with MRA, skull routine, orbital CT, and cerebral angiography did not reveal brainstem lesions, skull fractures, or vascular anomalies. These generalized KCL algorithms were used in segmenting the ophthalmological MRIs. KCL, FKCL and FSKCL comparisons are made. Overall, the FSKCL algorithm is recommended for use in MR image segmentation as an aid to small lesion diagnosis.     

A test of performance of breast MRI interpretation in a multicentre screening study

OBJECTIVES: The aim of this study was to assess the consistency and performance of radiologists interpreting breast magnetic resonance imaging (MRI) examinations. MATERIALS AND METHODS: Two test sets of eight cases comprising cancers, benign disease, technical problems and parenchymal enhancement were prepared from two manufacturers' equipment (X and Y) and reported by 15 radiologists using the recording form and scoring system of the UK MRI breast screening study [(MAgnetic Resonance Imaging in Breast Screening (MARIBS)]. Variations in assessments of morphology, kinetic scores and diagnosis were measured by assessing intraobserver and interobserver variability and agreement. The sensitivity and specificity of reporting performances was determined using receiver operating characteristic (ROC) curve analysis. RESULTS: Intraobserver variation was seen in 13 (27.7%) of 47 of the radiologists' conclusions (four technical and seven pathological differences). Substantial interobserver variation was observed in the scores recorded for morphology, pattern of enhancement, quantification of enhancement and washout pattern. The overall sensitivity of breast MRI was high [88.6%, 95% confidence interval (CI) 77.4-94.7%], combined with a specificity of 69.2% (95% CI 60.5-76.7%). The sensitivities were similar for the two test sets (P=.3), but the specificity was significantly higher for the Manufacturer X dataset (P<.001). ROC curve analysis gave an area under the curve of 0.85 (95% CI 0.79-0.92) CONCLUSIONS: Substantial variation in all elements of the scoring system and in the overall diagnostic conclusions was observed between radiologists participating in MARIBS. High overall sensitivity was achieved with moderate specificity. Manufacturer-related differences in specificities possibly occurred because the numerical thresholds set for the scoring system were not optimised for both equipment manufacturers. Scoring systems developed on one equipment software may not be transferable to other manufacturers.     

Gd-enhanced MR imaging of brain metastases: Contrast as a function of dose and lesion size

MR imaging contrast of brain metastases after cumulative doses of gadolinium chelate is quantitated and compared in order to assess the clinical utility of high dosage. T1-weighted spin-echo MR images of 39 patients with metastatic brain tumors were made before and after each of three equal doses cumulating to 0.1, 0.2 and 0.3 mmol Gd-complex per kg body weight. Quantitation of MRI contrast was limited to homogeneous brain metastases larger than 3 mm (n = 246). Post-Gd MRI contrast doubled with dose escalation from 0.1 to 0.3 mmol/kg and also increased with lesion size, by a factor of 2.5 between metastases of 3 and 16 mm diameter, that is after correcting for partial volume effect. At 0.2 and 0.3 mmol/kg the respective numbers of visible metastases increased by 15% and 43% compared with 0.1 mmol/kg (p < 0.0001, both). Image contrast figures differed significantly between doses (p = 0.018). Both the number of metastases and the image contrast is significantly higher when dose escalation is performed. It is indicated that the number of detected metastases will increase further at Gd doses beyond 0.3 mmol/kg. Post-Gd MRI contrast increases with lesion size, to an extent that can not be attributed to partial volume attenuation.     

MR assessment of spinal metastases using the late 26 sequence

Ninety-two patients with suspected spinal involvement by systemic cancer underwent MR examinations using both conventional and phase-contrast (LATE 26) spin-echo pulse sequences. MR imaging was considered positive for metastatic disease in 73 cases. Implants were extradural in 69 patients and intradural in 4 patients. Nineteen cases had no MRI evidence of metastases and the abnormalities suspected were shown to be due to either inflammatory or degenerative changes. MR appearances during and after chemo- and/or radiotherapy were studied in 5 patients. The impact of the LATE 26 sequence in the assessment of metastatic spinal disease is evaluated.     

Usefulness of MRI for the pre-operative evaluation of the pulmonary arteries in Tetralogy of Fallot

Adequate pre-operative evaluation of patients with Tetralogy of Fallot (TF) includes cine-angiography to delineate the pulmonary vasculature and the coronary artery anatomy and to demonstrate the presence of multiple ventricular septal defects (VSDs). All other information is obtained from color-Doppler-echocardiography. Magnetic resonance imaging (MRI), using the spin-echo sequence and cine-angiography was employed on 18 patients with TF, four of whom had aorto-pulmonary shunts. Mean age at MRI was 12.9 m (SD 2.3 m) and 14.3 m (SD 2.8 m) at cine-angiography. To compare MRI and cine-angiography we measured the ascending aorta, the main, the left and right pulmonary arteries and each structure at three levels. Diagnostic agreement between the two imaging methods was found if, for each modality, one of the three measurements in one structure differed by more than 40% from the other two measured in case of a local stenosis, and the diameter of the main pulmonary artery was less than 60% of the aorta to diagnose hypoplasia of the main pulmonary artery. There was close agreement between cine-angiography and MRI. With regard to the intracardiac anatomy, MRI was superior to color-Doppler-echocardiography in the depiction of aortic override and of right ventricular hypertrophy. In three cases local stenoses in the pulmonary arteries were detected by MRI and cine-angiography. Hypoplasia of the main pulmonary artery was detected by MRI in six patients and by cine-angiography in five patients. Cine-angiography missed one case of hypoplasia. In the remaining 11 patients normal findings were found by MRI and cine-angiography. For the demonstration of shunts, gradient-recalled-echo MRI is expected to give better results than the spin-echo sequence which depicted two out of four shunts in this series. Cine-angiography can be substituted by MRI in delineating the pulmonary arteries. New developments in MRI indicate the feasibility of delineating the coronary arteries.     

Primary retroperitoneal teratoma in the adult: correlation of MRI features with CT and pathology

Primary benign teratoma of the retroperitoneum is a rare tumor in the adult population. Only one case with an MRI examination has been reported in the English literature. This paper describes the CT and MRI features of a retroperitoneal teratoma in a 24-year-old male and discusses the value of MRI in the diagnosis and the preoperative imaging of such a tumor.     

Abdominal imaging studies: comparison of diagnostic accuracies resulting from ultrasound, computed tomography, and magnetic resonance imaging in the same individual

We retrospectively compared the diagnostic accuracy of abdominal ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) studies performed on the same individual to determine the relative performance of these modalities in the evaluation of disease processes, arising from different intra-abdominal organ systems. We retrospectively reviewed all procedure codes accrued by our abdominal imaging section during a 1-year period to determine how many patients underwent all three imaging procedures in our institution within a 2-week interval. These cases were then further evaluated to determine: (1) the primary organ system of disease involvement, (2) the final diagnosis, and (3) the imaging modality that provided the most accurate information upon which appropriate medical management was based. Imaging findings were determined by review of diagnostic reports, and medical management was determined by chart review. Two thousand six hundred-ninety five patients underwent ultrasound, 4,394 patients underwent CT, and 872 patients underwent MRI for the investigation of abdominal disease. Among these 5,126 patients, 26 underwent sequential US, CT, and MRI evaluation within a two-week interval. Appropriate clinical management was based on the US findings in 12/26 cases (46%; 95% CI: 27-67%), CT findings in 16/26 cases (62%; 95% CI: 41-80%), and MRI findings in 24 cases (92%; 95% CI: 75-99%). Significant differences in directing appropriate clinical management were found when comparing the relative diagnostic accuracies of MRI to US (p = 0.0003) and MRI to CT (p = 0.009). However, differences were not significant when comparing CT to US (p = 0.27). All final diagnoses in a given patient were accurately determined by US in 7/26 cases (27%), by CT in 10/26 cases (38%), and by MRI in 23/26 cases (88%). When analyzed according to individual diagnoses (61 total), US detected 33 of 61 (54%) abnormalities, CT detected 41 (67%) abnormalities, and MRI detected 51 (84%) abnormalities. US correctly characterized 32 (52%) abnormalities, CT correctly characterized 36 (59%) abnormalities, and MRI correctly characterized 49 (80%) abnormalities. Ultrasound, CT, and MR imaging correctly diagnosed the disease process in 3 of 12 (25%), 3 of 12 (25%), and 10 of 12 (83%) patients, respectively, with liver disease; 2 of 9 (22%), 6 of 9 (66%), and 9 of 9 (100%) patients, respectively, with pancreatic disease; 17 of 17 (100%), 8 of 17 (47%), and 10 of 17 (58%) patients, respectively, with gallbladder and biliary disease; 2 of 8 (25%), 5 of 8 (63%), and 5 of 8 (63%) patients, respectively, with renal disease; 0 of 3 (0%), 2 of 3 (66%), and 3 of 3 (100%) patients, respectively, with adrenal disease; and 8 of 12 (75%), 12 of 12 (100%), and 12 of 12 (100%) patients with free intraperitoneal fluid. Our results provide new information, regarding the relative benefits of ultrasound, CT, and MRI for the investigation of abdominal diseases at our institution. This initial data suggests that ultrasound provides the most accurate diagnoses in the investigation of gallbladder disease; MRI provides the most accurate diagnoses in the investigation of hepatic, adrenal, and pancreatic disease; and either CT or MRI may be the most appropriate first imaging study for the detection of renal disease.     

Real-time exercise stress cardiac MRI with Fourier-series reconstruction from golden-angle radial data

Magnetic resonance imaging (MRI) can measure cardiac response to exercise stress for evaluating and managing heart patients in the practice of clinical cardiology. However, exercise stress cardiac MRI have been clinically limited by the ability of available MRI techniques to quantitatively measure fast and unstable cardiac dynamics during exercise. The presented work is to develop a new real-time MRI technique for improved quantitative performance of exercise stress cardiac MRI. This technique seeks to represent real-time cardiac images as a sparse Fourier-series along the time. With golden-angle radial acquisition, parallel imaging and compressed sensing can be integrated into a linear system of equations for resolving Fourier coefficients that are in turn used to generate real-time cardiac images from the Fourier-series representation. Fourier-series reconstruction from golden-angle radial data can effectively address data insufficiency due to MRI speed limitation, providing a real-time approach to exercise stress cardiac MRI. To demonstrate the feasibility, an exercise stress cardiac MRI experiment was run to investigate biventricular response to in-scanner biking exercise in a cohort of sixteen healthy volunteers. It was found that Fourier-series reconstruction from golden-angle radial data effectively detected exercise-induced increase in stroke volume and ejection fraction in a healthy heart. The presented work will improve the applications of exercise stress cardiac MRI in the practice of clinical cardiology.