Characterization of hepatic neoplasms: contribution of magnetic resonance

The reliability of MR imaging in the diagnosis and characterization of space occupying lesions affecting the liver are discussed in this study. We discuss the role of MR imaging in the diagnosis of these tumours and its advantages compared with other available techniques such as ultrasonography and CT. We also discuss the results of MR in the characterization of focal neoplastic masses.     

MR arthrography of the shoulder joint in a postoperative patient sample

Indications of MR arthrography were analyzed in this prospective study. The aim was to evaluate possible advantages over conventional MRI, establish diagnostic criteria and to analyze its meaning further for the therapeutic management of postoperative patients. MR arthrography was performed in eight patients who had undergone surgical repair of rotator cuff lesions (modified Neer acromioplasty) and in six patients who had undergone arthroscopic therapy of recurrent unidirectional dislocation of the shoulder by combined arthroscopic intra- and extracapsular repair. MR investigations were performed before and after application of a contrast solution (2 mmol Gd-DTPA). All patients suffered from chronic postoperative pain. In patients with rotator cuff lesions, a partial tear could be verified in one patient and excluded in all others. In patients after arthroscopic therapy by combined intra- and extracapsular repair, a radiologically patulous-appearing capsule correlated with clinically recurrent dislocations. In all other patients diagnostic criteria, such as distribution of the intra-articular contrast solution, proliferation of scar tissue, nodular appearance of the glenohumeral ligaments and capsule thickness, correlated with a regular postoperative status. MR arthrography of the shoulder represents a promising method in the evaluation of the postoperative shoulder. It might further improve the evaluation of reactive capsule alterations, scar tissue proliferation, and the labroligamentous complex, as well as the ability to differentiate partial and complete rerupture from degenerative changes of the rotator cuff.     

FDG PET in head and neck cancer

In our extensive experience with FDG PET imaging in head and neck cancer, we have found the technique to be of high accuracy but of limited usefulness. This seeming paradox arises from several causes. Competing techniques such as CT, MR imaging, and even clinical examination already have good accuracy. In addition, high-resolution studies such as CT and MR imaging provide information required for treatment planning that is unavailable from FDG PET images. The high cost of FDG PET militates against its use in this setting, in which only a small marginal gain can be expected. In the special problem areas in which FDG PET might be expected to offer unique advantages, such as screening for second primary lesions, searching for unknown primary lesions, or differentiating benign salivary rumors from malignant lesions, the results of FDG PET have been disappointedly poor. Of these special problem areas, only the question of accuracy in finding occult primary lesions appears unresolved and in need of further study. The single application in which FDG PET appears to be advantageous is the posttherapy setting. In this setting, the technique is definitely superior to alternative methods of determining tumor recurrence and differentiating posttherapy sequelae such as radiation necrosis from tumor recurrence. We believe that considerable opportunity remains for further research on the use of FDG PET in head and neck cancer. Other agents such as 11C-methionine for example, might improve the diagnostic accuracy of FDG PET in some of the problem areas that we have identified, such as the early postirradiation period. We currently have such a study under way. Also, because FDG PET offers a unique way to measure tumor metabolism, further investigation of the use of FDG PET tracers to evaluate various biologic parameters such as proliferation rates or tumor hypoxia are needed. Such studies could provide a noninvasive technique to identify which fractionation schemes or combinations of therapy might be useful for individual patients. A final caveat is in order. Although our findings of the usefulness (and lack thereof) of FDG PET in head and neck cancer may be disappointing to many, these results should not be generalized to other applications of FDG PET in oncology. Each tumor type and setting presents its own specific problems, and in some instances FDG PET offers unique advantages over other imaging techniques. A good example is the setting of primary lung cancer, in which FDG PET appears clearly superior to all other methods of pretherapy screening [19-20].     

Neuroimaging and efficacy of treatment in advanced African trypanosomiasis

INTRODUCTION: West African trypanosomiasis (WAT) is rare in Spain. Delay in its diagnosis and treatment leads to irreversible diffuse meningoencephalitis and finally death of the patients. CLINICAL CASE: We described a patient in whom the diagnosis of advance WAT had been delayed. He had headache, alteration of the level of consciousness and sleep pattern, psychiatric disorders, crises, extrapyramidal, sensitive and endocrinological clinical alterations. Biochemical investigation showed slight anemia with marked thrombocytopenia, and raised ESR and IgM. Initially serology was negative for trypanosomes, although examination of the CSF confirmed the diagnosis. MR showed extensive lesions of the basal nuclei, brainstem and white matter. Both the clinical abnormalities and the lesions shown on MR disappeared after treatment with intravenous difluoromethylornithine. The patient is now symptom-free and at work as usual. DISCUSSION: Find diagnosis of WAT requires isolation of the parasite from the blood, the bone marrow or CSF. When other complementary tests (such as serology) are negative, the diagnosis should not be ruled out. There are few neuroimaging studies of WAT, and only by CT. We have found no MR studies of patients with WAT, in the literature. We emphasize the close correlation between the clinical and radiological findings in this case, and the excellent result obtained after treatment.     

Efficacy of dynamic susceptibility contrast MRI using echo-planar imaging in differential diagnosis of breast tumors

It has been shown that T1-weighted dynamic MR imaging is a useful method in differentiating malignant breast tumors from benign lesions. Invasive breast carcinomas enhance more rapidly than benign lesions such as fibroadenomas, papillomas, and proliferative fibrocystic diseases. However, significant overlap in the dynamic profile of benign and malignant lesions may occur, resulting in relatively low specificity, which is an inherent limitation of this technique. The author attempted to improve diagnostic accuracy by utilizing dynamic susceptibility contrast MR imaging (DSC-MRI) with a single-shot echo-planar imaging sequence. Twenty-two patients underwent DSC-MRI using a 1.5-T unit (Magnetom Vision, Siemens). Images were obtained before, during and after the bolus injection of 20 mL of gadopentetate dimeglumine. The signal reduction rate within the first 30 seconds (delta RT2) was calculated by the following equation: delta RT2 = (postcontrast signal intensity-precontrast signal intensity)/precontrast signal intensity. A rapid, strong decrease in signal intensity was observed on the first pass of the contrast material in all cases of carcinoma, whereas no or only a minimal decrease in signal intensity was observed in all but one of the benign lesions. This method seems to be more accurate than T1-weighted dynamic MR imaging in the differentiation benign and malignant breast lesions. Since DSC-MRI can be performed quickly, subsequent conventional T1-weighted imaging can provide additional information about the morphologic features of lesions, to further support the diagnosis. In conclusion, DSC-MRI seems to be a promising method for the accurate preoperative assessment of breast lesions.     

Application of anticancer agent embolism in Miles'' operation

A double-blind prospective study was done with 15 patients with anterior shoulder instability to determine the diagnostic efficacy of magnetic resonance (MR) imaging versus arthroscopy in the evaluation of chondral or osteochondral lesions of the humeral head. MR produced 6 true positives, 5 true negatives and 4 false negatives, and its accuracy and sensitivity were 60% and 87%, respectively, whereas arthroscopy gave 8 true positives, 5 true negatives and 2 false negatives, with a sensitivity of 80% and an accuracy of 87%. All lesions diagnosed with either method were regarded as positive by definition, with the result that the specificity was always 100%. The differences in diagnosis sprang from the false negatives. The 40% discrepancy between the two methods was probably due to our distinction in MR between intra- and extra-articular osteochondral lesions. In the first group (the 4 MR false negatives), there were three instances of first-degree intra-articular lesion and one diagnostic error (third-degree lesion). In the second (the 2 arthroscopy false negatives), the lesions were of the extra-articular type. It is thus advisable to employ both of these methods to ensure the correct diagnosis of a Hill-Sachs lesion, and hence the correct choice of treatment.     

Cognitive dysfunction and impaired organization of complex motility in degenerative parkinsonian syndromes

PURPOSE: Our purpose was to present imaging findings of six cases proven or supposed to be von Meyenburg complexes (VMCs) with a basis of reviewing the pathologic literature and to describe imaging points for the diagnosis of typical VMC along with its differential diagnosis. METHOD: Six cases were diagnosed as VMC of the liver with imaging modalities (one had histopathologic proof). Both ultrasound (US) and CT were available for all cases, and MRI was used for three cases. Follow-up with US, CT and/or MRI was performed in five cases. RESULTS: US detected varying abnormalities of the livers in four cases. CT and MRI revealed multiple or numerous intrahepatic tiny (usually < 5 mm) cystoid lesions in all of the cases. The lesions were scattered throughout the livers, and some of them were located more frequently adjacent to the medium-sized portal veins than to the hepatic veins of similar size on CT. Moreover, some lesions were apparently located in the subcapsular areas (up to the hepatic capsules). They were usually irregular in shape and showed no enhancement but increased in number by approximately 80-150% after administration of intravenous contrast medium. The T2-weighted MR images and MR cholangiopancreatography showed the lesions to be much more apparent and to be more numerous than T1-weighted images did. Follow-up of five cases with imaging modalities did not show remarkable change of the lesions. CONCLUSION: Despite our limited experience, VMC lesions seem to show some CT and MR features different from those of other multiple small hepatic lesions. They presented as multiple or numerous intrahepatic tiny cystoid lesions usually with irregular contour, scattered throughout the liver up to the subcapsular areas, and were detected in far greater number by enhanced CT or T2-weighted MR images than by unenhanced CT or T1-weighted images. They showed no remarkable change on long term follow-up imaging. We propose that a diagnosis of typical VMC could be made after analyzing CT or MR images carefully with good understanding of its pathologic basis, but imaging follow-up is necessary in oncology patients.     

Magnetic resonance imaging of renal lymphoma with computed tomography correlation

The magnetic resonance (MR) imaging and computed tomography (CT) findings in four patients (five kidneys) with non-Hodgkin's lymphoma involving the kidneys and perirenal spaces are presented. The patterns of disease in each case were as follows: bilateral renal nodules, infiltration in the perirenal space, infiltration in the perirenal space with renal involvement, and direct invasion from contiguous retroperitoneum. On plain CT, the lesions showed slight hyperdensity (three kidneys) and isodensity (two kidneys) as compared with normal renal parenchyma. But all lesions appeared as hypodense masses with more definite margins after contrast enhancement. MR imaging findings showed iso- or slight hypointense masses on T1-weighted images and definite hypointense masses on T2-weighted images as compared with the signal intensity of the renal cortex. Dynamic imaging and conventional delayed T1-weighted imaging following Gd-DTPA injection showed no significant enhancement of the lesions. In comparison with contrast enhanced CT, despite its poorer resolution, T2-weighted MR imaging showed nearly the same accuracy in the evaluation of number and extent of the lesions without contrast medium administration. MR imaging was also useful to evaluate the patency of vessel lumen surrounded by tumor mass and to determine the location and extent of huge lesions by its multiplanar imaging capabilities.     

Practical considerations in the scintigraphic evaluation of endocrine hypertension. The adrenal cortex and medulla

A nuclear scan maps the distribution of a radiopharmaceutical that is specific for a physiologic property of a targeted tissue. As such, it is not limited by the anatomic changes necessary for CT and MR scans. It is just because of this that maps of specific metabolic precursors of adrenal medullary and cortical hormones offer information crucial to the therapeutic strategy of endocrine hypertension. NP-59 and MIBG scans can specify the nature of abnormalities revealed by anatomic images and because of the ease of surveying the whole body can give transcendent information about lesions remote from the adrenals. In instances when the origin of endocrine hypertension is not forthcoming from CT or MR imaging or when the anatomic and biochemical findings are in conflict, NP-59 or MIBG can almost always provide the answer.     

Comparison of computerized tomography and magnetic resonance in the assessment of benign and malignant pleural diseases

To compare the diagnostic capabilities of Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) in differentiating benign from malignant pleural disease, we examined with MRI at 0.5 T forty-five patients with pleural lesions identified on CT scans. For 34 patients, a final diagnosis of malignant (n = 18) or benign (n = 16) disease was made. T1, proton density/T2 and enhanced T1-weighted spin-echo images were acquired. CT and MR images were independently studied by two observers, who were unaware of the final diagnosis. Various morphological features suggesting benign or malignant pleural disease were evaluated. On the basis of the morphological CT features, a final diagnosis of benignity of malignancy was expressed in terms of two different levels of confidence-probable or definitive. The MR signal intensity of pleural lesions was compared with that of intercostal muscles (isohypointense or hyperintense). No significant differences were observed between CT and MR morphological findings. High signal intensity on proton density/T2-weighted images was observed in all malignant lesions and in 2 benign lesions (100% sensitivity, 87% specificity). In the absence of this sign (i.e., isointense or hypointense signal), the lesions were always benign (100% negative predictive value). All the definitive CT diagnoses were correct, while 6 of 17 probable CT diagnoses were incorrect. In the subgroup of lesions misinterpreted with CT, MR signal intensity on long-TR images always allowed the correct differentiation of benign from malignant conditions. To conclude, MR signal intensity is a valuable additional feature to differentiate benign from malignant pleural disease. We suggest the use of MRI in the pleural lesions where the level of confidence of CT diagnosis is low.     

Fat necrosis after trauma: a benign cause of palpable lumps in children

OBJECTIVE: Our objective is to describe the clinical entity and MR imaging appearance of fat necrosis after trauma, a benign cause of palpable soft-tissue lesions in children. A related objective is to establish MR imaging criteria that can be used reliably to differentiate this entity from other more serious causes of soft-tissue masses. CONCLUSION: Fat necrosis after trauma is a common cause of palpable lumps in children and has a benign course on long-term follow-up. When characteristic MR imaging findings are seen, conservative therapy is appropriate.     

Value of CT scan and MRI in primary tumors of the ovary

Characterisation of an ovarian mass is of utmost importance in the preoperative evaluation of an ovarian neoplasm. It enables the surgeon to anticipate carcinoma of the ovary before the operation, so that adequate procedures are planned. Although, ultrasonography (US) remains the foremost imaging modality for screening patients with adnexal lesions, computed tomography (CT) recently has proved to be of value in the characterisation and management of tumors of the ovary. Magnetic resonance (MR) imaging has also been shown to have a high degree of diagnostic specificity for certain types of ovarian masses, such as dermoid cysts, and endometriomas. However, the potential of MR imaging to characterize tumors of the ovary has not yet been established. This study assesses the value of MR imaging and CT for the purpose of predicting the malignancy of ovarian lesions, and comparing findings of MR imaging with those of CT.     

False-negative MR imaging of malignant breast tumors

In this study we analyze MR-negative malignant lesions of the breast. A total of 204 patients with palpable and/or mammographic lesions were studied. The MR technique consisted of the turbo FLASH and MP-RAGE subtraction techniques. All patients underwent surgical biopsy and/or mastectomy and all specimens were examined by the correlative radiologic-histologic mapping technique. A total of 208 lesions were evaluated; 145 turned out to be malignant and 63 proved to be benign. Six malignant lesions were misinterpreted as benign on MR imaging; thus, suspicious contrast enhancement was present in 96 % of the lesions detected by mammography, US, or clinical examination. Especially 4 of the 17 ductal carcinoma in situ (DCIS) lesions were misinterpreted (23.5 %). Despite optimal technique, 6 malignant lesions were not identified by MR imaging. The highest prevalence of these MR occult lesions was in the group of DCIS. Although MR imaging has an important role in the evaluation of breast lesions and, primarily, in ruling out malignancy, one should be aware of the fact that false-negative MR findings do occur.     

Computer-aided studies on the spatial structure of the small hepatitis B surface protein

Progressive Multifocal Leukoencephalopathy (PML) is a subacute demyelinating opportunistic infection of the central nervous system which frequently occurs in AIDS. CT and MR, together with clinical and virological findings, can suggest a correct diagnosis in most cases, thus avoiding stereotactic biopsy which is too invasive considering the lack of therapy and the poor prognosis of this disease. In this study we reviewed the CT and MR findings of 16 proved AIDS-related PML cases. PML lesions appeared as hypodense on CT, hypointense on T1w, hyperintense on PDw and T2w MR images. CT was less sensitive than T2w MR images and underestimated the number of lesions and/or disease extent. On the basis of our findings during the progression of the lesions we observed two different patterns of PML presentation and evolution i.e., "single" and "multifocal". Single lesions generally involve subcortical white matter (arcuate fibers) of parietal lobe and spread to the contralateral hemisphere across the corpus callosum; multiple "patchy" lesions can be localized variably in the cerebral hemispheres and also in the brainstem and cerebellar hemispheres.     

Magnetic resonance (MR) imaging of the chest: state-of-the-art

To date, magnetic resonance (MR) is established as an imaging modality in the diagnosis of chest diseases. Because of its excellent distinction of vessels and soft tissue, MR can be performed as the primary imaging procedure before computed tomography in patients with suspected vascular lesions, mediastinal masses, hilar lesions, and pathological changes of the pleura and the chest wall. In these cases, MR is able to provide all the necessary diagnostic information. In other patients, a limited number of MR images may be helpful in cases of equivocal or confusing CT or clinical findings. More detailed information can be obtained, using surface coils or special imaging sequences, i.e. high resolution MR images of the pleura or angiographic images of mediastinal and pulmonary vasculature. From a clinical viewpoint, the most important task for thoracic magnetic resonance nowadays is the pretherapeutic evaluation of intrathoracic masses, the differential diagnosis of benign versus malignant lesions, and the accurate documentation of tumour extent in malignancies including three-dimensional-display to improve surgical or radiation planning. Future directions in thoracic magnetic resonance will be predominantly influenced by postprocessing approaches, specialized imaging techniques, and magnetic resonance-guided interventional applications.     

Cerebral paragonimiasis in early active stage: CT and MR features

OBJECTIVE: Diagnosis of cerebral paragonimiasis in its early active stage is important because curative chemotherapy is possible. Accordingly, this study was undertaken to evaluate the CT and MR features of early active cerebral paragonimiasis. MATERIALS AND METHODS: We retrospectively reviewed the CT scans (n = 29) and MR images (n = 7) of the brain in 20 patients between 7 and 59 years old who had cerebral paragonimiasis in the early active stage. The diagnosis was based on a positive antibody test by enzyme-linked immunosorbent assay (ELISA) for paragonimiasis in serum and CSF. The diagnosis was confirmed surgically in seven patients. RESULTS: The most common and characteristic imaging finding was a conglomerate of ringlike enhancing lesions (grape-cluster appearance) with surrounding edema in one cerebral hemisphere in 11 patients (55%). Other nonspecific findings included a solitary ringlike lesion (n = 4) or irregular enhancing lesions (n = 2), localized hemorrhage with (n = 3) or without (n = 2) enhancing lesions, and a poorly defined non-hemorrhagic, nonenhancing lesion (n = 1). CONCLUSION: CT and MR findings of clustered ring-enhancing lesions, seen in approximately half of the cases of early cerebral paragonimiasis, are suggestive of cerebral paragonimiasis.     

Correlating MR lesions and functional deficits in multiple sclerosis patients. Anatomical atlas registration

Although brain magnetic resonance (MR) imaging is increasingly being used as an objective outcome measure in treatment trials for multiple sclerosis (MS), findings correlating conventional MR imaging and disabilities in established MS have been inconsistent. In some studies, measures of MR lesion status, such as numbers of lesions or MS lesion load (volume), have shown limited correlations with clinical scores such as the Kurtzke Expanded disability scale (EDSS). Other studies have shown clear correlations between MR findings and measures of disability in MS. Further development of image processing techniques should help elucidate the relationships between MR findings and disease processes in MS.     

Gadolinium-enhanced MR imaging of temporomandibular disorders: improved lesion detection of the posterior disk attachment on T1-weighted images obtained with fat suppression

OBJECTIVE: The purpose of this study was to assess the potential for improved lesion detection in the posterior disk attachment and its surrounding tissue in temporomandibular disorders when gadolinium-enhanced MR imaging performed with fat suppression is used. MATERIALS AND METHODS: Forty-five patients underwent MR imaging with conventional T1- and T2-weighted, gadolinium-enhanced T1-weighted, and gadolinium-enhanced fat-suppressed spin-echo imaging sequences. Qualitative and quantitative assessments of the contrast enhancement of each type of imaging were also performed. RESULTS: The contrast-enhanced fat-suppressed T1-weighted imaging sequence had several advantages over the other imaging techniques in detecting abnormalities of the posterior disk attachment and in detecting bone marrow lesions in the mandibular condyle. The most significant advantage was better enhancement of lesion conspicuity. The diagnostic accuracy of contrast-enhanced fat-suppressed imaging was 77% versus 70% for conventional contrast-enhanced imaging. The kappa value for interobserver agreement was .95 for contrast-enhanced fat-suppressed imaging and .72 for conventional contrast-enhanced imaging. CONCLUSION: Contrast-enhanced fat-suppressed T1-weighted spin-echo MR imaging is a valuable technique for visualizing the extent and degree of lesions in the posterior disk attachment and bone marrow lesions in the mandibular condyle.     

Bone marrow imaging in children

By virtue of its ability to separate hematopoietic from fatty marrow, MR imaging is ideal for detecting marrow lesions. This article reviews the techniques of bone marrow imaging, interpretive pitfalls, anatomic variations with patient age, and the alterations in bone marrow signal occurring in a variety of pathologic conditions.     

MR of the brain in children

MR imaging has firmly established its place as the cornerstone of pediatric neuroimaging. Recent advances in MR imaging have led to decreased imaging time, high resolution studies, and new methods for obtaining tissue contrast. Magnetic resonance angiography (MRA) now obviates the need for angiography in some children, although its extended role is still to be defined. Normal and abnormal development and myelination patterns have been further defined with MR imaging. The patterns of brain injury resulting from hypoxia and ischemia vary with the degree of the insult as well as the gestational age of the child. These patterns of hypoxic-ischemic encephalopathy can be analyzed to determine when the insult occurred. Neuronal migration disorders and phakomatoses can be diagnosed with confidence at an early age, thus facilitating genetic counseling. MR imaging can detect the most common lesions associated with childhood epilepsy, such as hippocampal sclerosis, focal cortical dysplasias, and low-grade tumors. Other areas, including pediatric AIDS, toxicity-related injury, metabolic/mitochondrial conditions, and disorders associated with iatrogenic injury, can be diagnosed with MR. Spectroscopy provides information that should prove useful in evaluating and monitoring neuronal and other brain tissue disorders in children.