Lesions of the ovary with T1-hypersignal.

Pelvic magnetic resonance imaging (MRI) has been used successfully to diagnose ovarian masses that cannot be adequately evaluated using pelvic ultrasound. T1 hyperintensity is a common finding in an ovarian mass and has important diagnostic implications. The aims of this review are to list the substances that may produce high signal intensity on T1-weighted MRI, to explain the physical basis for causes of the high T1 signal intensity, and to describe common and uncommon T1 hyperintense ovarian lesions. The morphological findings, the imaging features of the additional sequences, and clinical variables can help in the differential diagnosis, and in some cases, enable a specific diagnosis, leading to appropriate management of the patient.

[Pre-operative diagnosis of bucket-handle meniscal tears: clinical evaluation and value of arthroscan and MRI radiological criteria]. / Diagnostic préopératoire des anses de seau méniscales: valeur des critères cliniques, arthro-TDM et IRM.

PURPOSE OF THE STUDY: It is important for both the patient and the surgeon to determine whether a meniscal lesion can be repaired before undertaking surgery. The purpose of this study was to examine the pertinence of clinical signs and determine the value of imaging findings for the preoperative diagnosis of bucket-handle meniscal tears. This preliminary study was conducted before undertaking an analysis of preoperative criteria of reparability in a homogeneous group of meniscal lesions. MATERIAL AND METHODS: This retrospective series included 33 arthroscopically-proven bucket-handle meniscal tears in patients who underwent arthrography and/or arthroscan and/or MRI preoperatively. The images were reviewed by two senior radiologists who established a consensus diagnosis. Clinically, the type of blockage and the presence of permanent flexion before surgery were noted. The following items were noted on the imaging results: fragment displacement (fragment in the notch on the coronal slice) anterior megahorn, double PCL, and serpent sign on the sagittal slice. Longitudinal, transversal extension and position of the bucket-handle were noted. We searched for correlations with the intraoperative findings. RESULTS: Fourteen patients had a history of knee blocking and 15 had permanent flexion before surgery. Only 10 patients had the typical association of blocking and flexion. Certain diagnosis of bucket-handle meniscal tear was provided by MRI (13/15), arthroscan (6/7), and arthrography (10/24) giving an equivalent sensitivity for the two slice imaging techniques. The sign of a fragment in the notch on the coronal slice was a constant finding. The double PCL sign was sensitive for medial meniscal tears and for lateral meniscal tears with associated ACL tears. The diagnosis was successfully established in all 9 patients who underwent several explorations (2 or 3). Buckle-handle meniscal tear was not identified in 9 patients (arthrography 7, MRI 2). DISCUSSION: Our findings demonstrate that the preoperative diagnosis of bucket-handle meniscal tears cannot be properly established on clinical criteria of typical blocking and/or permanent flexion. They confirm that arthrography is not contributive to diagnosis and that the absence of a slice image is detrimental to diagnosis. The sensitivity of the two slice imaging methods was similar. The key sign was the presence of a fragment in the notch on the coronal slice; in the three cases where this sign was absent, the reason was found to be the small size of the displaced fragment (resolution limit) and time between imaging and arthroscopy. The characteristic features of the bucket-handle lesions observed in this series are exactly the same as reported in earlier reports but to our knowledge provide the first data on comparative performance of arthroscan and MRI. CONCLUSION: The noninvasive nature of MRI and the possibility of assessing the meniscal wall and the quality of the meniscal tissue make MRI the exploration of choice for preoperative assessment of meniscal tears.

[Thoracic pseudo-lesions induced by inadequate methodology, optical illusions, and anatomical variations]. / Les pseudo-pathologies thoraciques induites par des techniques incorrectes, illusions visuelles et variations anatomiques.

False-positive or over-calling of findings at chest radiography may have important consequences by generating numerous and unnecessary examinations. The advances made in thoracic imaging have currently decreased the number of technical errors. However, we are frequently confronted with visual illusions or with failure to recognize anatomical variants, either congenital, age-related or physiological in nature. Other difficulties are due to functional variations. Over-calling depends on the clinical context, which may inadequately suggest an interstitial lung process, abnormalities of the vascularization or of the hila. In this article, several examples of false positives will be illustrated. An explanation for these appearances, based on the underlying etiology, will be provided.

PET-CT and diagnostic CT: the synergy of metabolic and morphological data in onco-haematology.

PURPOSE: Our goal was to determine how interpreting diagnostic CT together with PET-CT could improve the assessment of morphology in onco-haematology. PATIENTS AND METHODS: Fifty-nine patients with aggressive lymphoma were retrospectively included. The diagnostic CT scan was interpreted by two radiologists, followed by a combined analysis of the CT and the PET-CT carried out by two specialists in metabolic and morphological imaging. The diagnostic performances were assessed in terms of sensitivity and specificity, then concordance and discordance rates (kappa) were studied. RESULTS: A combined interpretation of CT and PET-CT showed better diagnostic performances than those of interpretations of CT only in the assessment of nodal sites (826 sites, sensitivity of 99% versus 85%, P<0.05), extranodal sites (649 sites, sensitivity of 88% versus 78%) and bone sites (one analysed per patient, sensitivity of 50% versus 27%). The combined interpretation also improved inter-observer agreement and led to an upgraded Ann Arbor staging in 15% of patients, with a change of treatment in 10%. CONCLUSION: Interpretation of diagnostic CT in onco-haematology can be improved by combining it with an assessment of PET-CT. The synergy between metabolic and morphological information leads to improved diagnostic capabilities and renders interpretations more reproducible.

Pathologies of the male breast.

The majority of breast lesions in men are benign. Gynaecomastia is a very common condition in which hormonal changes cause male breasts to enlarge. Three radiological patterns of gynaecomastia have been described: nodular, dendritic, and diffuse glandular pattern. The main differential diagnosis is lipomastia, which is when adipose tissue deposits are found in the subcutaneous tissue. Male breast cancer is rare. The main risk factors are pathologies that cause hormonal imbalances, a history of chest irradiation, and a family history of breast cancer (particularly in families carrying a mutation of the gene BRCA2). Mammography usually shows a mass with no calcifications. Sonography is useful to investigate local disease spread, and for detecting any enlarged axillary lymph nodes. MRI is not currently indicated to investigate male breast cancer. Very often, the clinical examination alone is enough to distinguish benign lesions from malignant lesions. Imaging must not be automatically carried out, but rather it should be used when the diagnosis is clinically uncertain or when patients present risk factors for breast cancer, as well as for guiding biopsies and for assessing disease spread.

[Accuracy of CT-guided chest biopsy for benign lesions]. / Performance de la biopsie transthoracique et lésions bénignes.

PURPOSE: To demonstrate that CT-guided chest biopsy can effectively prevent surgery for patients with benign tumors. PATIENTS AND METHODS: We present a cohort of patients who underwent CT-guided biopsy for a chest lesion where diagnosis could not be achieved through other means. The gold standard was defined, based on availability, by surgery or imaging and clinical follow-up over a 2-year period. RESULTS: From a total of 114 biopsied lesions, 101 were malignant and 13 were benign. Sensitivity and specificity values for benign lesions were 92.1 and 92.3% respectively with PPV and NPV of 60 and 98.9%. Sensitivity and specificity values for malignant lesions were 86.1 and 100% respectively with PPV and NPV of 100 and 48%. No statistically significant correlation could be established between the groups with concordant and discordant results. CONCLUSION: The diagnosis of specific benign lesion on CT-guided biopsy, all sizes and sites included, may effectively prevent unnecessary surgery.

Magnetic resonance imaging of skeletal muscle involvement in limb restricted vasculitis.

BACKGROUND: Limb restricted polyarteritis nodosa (PAN) and PAN-type diseases such as isolated vasculitis of skeletal muscle are localised vasculitides affecting the skin, muscles, or peripheral nerves, usually of the lower limbs. These diseases often present with non-specific clinical symptoms and normal laboratory values and electromyograms. The usefulness of magnetic resonance imaging (MRI) of skeletal muscle has been poorly investigated to date. OBJECTIVE: To describe the MRI findings in the legs of three patients with limb restricted vasculitides (two PAN, one isolated vasculitis of the skeletal muscle) with histologically established muscle involvement. METHODS: MRI was carried out on calf muscles and T(2) weighted images, unenhanced T(1) weighted images, and STIR sequences were obtained. RESULTS: Muscle damage resulted in oedema-like changes on MRI characterised by hyperintense signals in T(2) weighted and slow tau inversion recovery (STIR) sequences and normal unenhanced T(1) weighted sequences of one or several leg muscles. CONCLUSIONS: MRI should be considered a useful complementary examination that might facilitate the recognition of limb restricted vasculitides, and possibly indicate the site for muscle biopsy. It could also be useful in monitoring the course of the disease. Future studies should also evaluate MRI for systemic PAN or other systemic vasculitides with muscle involvement.

MR lymphography using iron oxide nanoparticles in rats: pharmacokinetics in the lymphatic system after intravenous injection.

The objective of the study was to quantify the kinetics of the superparamagnetic nanoparticle ferumoxtran (AMI 227, Sinerem(R), Combidex(R)) in the efferent lymph of the subdiaphragmatic lymph nodes and in various node groups of the rat to elucidate the uptake mechanism. The thoracic lymph duct was catheterized in 24 rats after an IV injection of 40 micromol Fe/kg ferumoxtran. Three rats were studied at several time points between 1.5 and 24 hours. At each time point, 0.3 ml of lymph were collected over 45 minutes. Lymph nodes were differentiated into five groups. The iron concentration in the samples and in plasma was measured by relaxometry at 0.47 T and atomic absorption spectrometry. Cytology was performed on the lymph. High concentrations of nanoparticles were found in the thoracic lymph soon after injection (90 minutes). No particle was found in the lymph cells, indicating that ferumoxtran was extracellular in the lymph fluid. The maximum concentration was reached later in all node groups, at 12 hours, and then plateaued. The transcapillary pathway and subsequent lymph drainage of the particles seem to play a major role in the delivery to the lymph nodes.

Distribution of iron oxide nanoparticles in rat lymph nodes studied using electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI).

Superparamagnetic iron nanoparticles have been developed as contrast agents for magnetic resonance lymphography. The kinetics of uptake of these particles has not yet been accurately determined. We have therefore monitored the distribution of individual iron particles (ferumoxtran, AMI-227, Sinerem) in rat lymph nodes 1.5, 3, 6, 12, and 24 hours after i.v. injection (two rats per time point). The ultrastructural distribution of the iron was determined by energy-filtered transmission electron microscopy (EFTEM). This method allows the identification of elements using element-specific energy-loss electrons. Iron was identified by the Fe-L(2,3) edge (EELS), and iron maps were obtained using iron-specific electrons for imaging (ESI). The background was calculated by simplex optimization (EELS) and by the two-window method (ESI). Ferumoxtran particles were regularly observed at the periphery of the lymph nodes but not in their centers. Isolated iron particles were seen extracellularly within lymph vessels and, 3 hours after injection, as small dots in phagocytic cells. Numerous dense clusters appeared within the cells at later times (6 and 12 hours after injection). These results suggest that the contrast agent moves rapidly across the capillary wall to the lymph and is then taken up by phagocytic cells. J. Magn. Reson. Imaging 2000;12:505-509.