Digital radiography of subtle pulmonary abnormalities: an ROC study of the effect of pixel size on observer performance

Forty conventional radiographs with examples of mild interstitial infiltrates and subtle pneumothoraces and 40 normal studies of the chest were selected and digitized, with pixel sizes of 1.0, 0.5, 0.2, and 0.1 mm. Observer performance tests were carried out using receiver operating characteristic analysis. Conventional radiographs and digitized images were compared. The results indicate that, in such cases, diagnostic accuracy increases significantly as the pixel size is reduced, at least to the 0.1-mm level. We conclude that, for digital systems using screen-film or similar image receptors, use of a pixel size substantially larger than 0.1 mm may result in some loss of diagnostic accuracy.     

The use of magnetic resonance imaging and spectroscopy in the assessment of patients with head and neck and other superficial human malignancies

The proper demarcation of diseased tissue is important for radiation therapy planning and treatment. The volume to be irradiated is usually identified on radiographs or on x-ray computed tomography (CT) sections. Magnetic resonance (MR)-derived images of the proton T2 relaxation times in small pixel elements, typically 0.5 mm2 or less, provide significantly sharper differentiation between normal and diseased tissue. The T2 values in tissue depend on the tissue composition, histologic condition, and physiologic environment within the tumor. Furthermore, for many tumors the histogram of T2 values has a clear biphasic distribution suggesting that T2 maps may be useful for the identification of necrotic or hypoxic regions within tumors. The distribution of T2 values within the tumor bed shows the general pattern that the T2 values are elevated with a range greater than that seen in normal muscle. Elevated T2 values are not by themselves diagnostic of malignancy; however, they demonstrate the heterogeneity of the microenvironment present within a tumor. The spatial distribution of T2 values is being explored as a method for computer assistance in the delineation of the target volume for treatment planning. In addition, MR P-31 spectroscopic examinations were performed on 30 patients with squamous cell carcinomas of the head and neck. Although hampered by muscle contamination in some P-31 spectra obtained with surface coil profile localization techniques, significant trends can still be appreciated in our data. These trends include the following: (1) the P-31 spectra from malignant tissue have well-resolved spectral lines in the upfield region that correspond to Pi, phosphomonoester (PME), and phosphodiester (PDE) not usually seen in normal muscle; (2) the PDE/B-ATP and PME/B-ATP ratios are greater than unity in all cases; and (3) most of the tumors have higher PME peaks than PDE peaks. The P-31 spectra from patients treated with ionizing radiation changed during and after therapy. Some of the changes could be associated with alteration of the tumor metabolic activity or synthesis and breakdown of lipoproteins. These studies suggest that magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) studies may be useful for both radiotherapy treatment planning and the noninvasive monitoring of patients both before and during treatment.     

Central nodal necrosis and extracapsular neoplastic spread in cervical lymph nodes: MR imaging versus CT.

Computed tomographic (CT) scans and magnetic resonance (MR) images obtained in 24 patients with cervical lymphadenopathy were retrospectively and blindly evaluated by two readers for the presence of central nodal necrosis (CNN) and extracapsular nodal spread (ENS). The CT studies were all enhanced, and the MR images were obtained with short repetition time (TR)/echo time (TE), long TR/double echo, and enhanced short TR/TE fat-suppressed sequences. Each MR imaging sequence was interpreted separately and then collectively. Sixty lymph nodes were identified with CT. Sensitivity for CNN was 16%-67% with the unenhanced MR pulse sequences, 50% with enhanced sequences, and 83%-100% with CT. The most accurate reading of MR images for CNN was with the unenhanced T1-weighted and T2-weighted images (86%-87%); the accuracy of CT was 91%-96%. The accuracy of MR imaging for detecting ENS was maximal with T1-weighted images (78%-90%). Gadolinium-enhanced, fat-suppressed images did not improve accuracy in evaluating CNN or ENS. CT is currently more accurate than unenhanced or enhanced MR imaging in detecting CNN or ENS.     

The Chiari-I malformation

We have described the important clinical features and aspects of the Chiari-I malformations, with particular emphasis on Chiari-I malformation. Previously thought to be a rare finding with only minor significance, Chiari-I malformation is an important cause of a variety of symptoms, and will be diagnosed even more frequently as the use of MRI increases. The clinician must consider Chiari-I malformation in any patient with unexplained sensorineural hearing loss, headache, vertigo, ataxia, dysequilibrium, dysphagia or other cranial nerve symptom, especially if accompanied by more classic symptoms of this disorder, such as cervical pain or weakness.     

Erythrokeratodermia Variabilis Present at Birth: Case Report and Review of the Literature

Abstract: A healthy boy had the distinctive lesions of erythrokeratodermia variabilis (EKV) at birth. Twenty-eight patients described in the literature had EKV that presented in childhood. Nine of the 28 were said to have had a rash since birth, but none were distinctive of EKV. To our knowledge this is the first well-documented case describing a child born with the skin manifestations of EKV. We conclude that patients with EKV are infrequently born with a rash, and that only very rarely when the rash is present is it suggestive of the disorder.     

Lymphocytic enterocolitis in patients with 'refractory sprue'

We describe a patient with refractory sprue with malabsorption, a flat small-bowel biopsy specimen unresponsive to a gluten-free diet, and colonic biopsy specimens consistent with lymphocytic (microscopic) colitis. To investigate further the relation between celiac disease and lymphocytic or collagenous colitis (a similar and possibly related entity), we examined colorectal and small-bowel biopsy specimens in patients indexed histologically as having celiac disease who have been seen at The Johns Hopkins Hospital since 1958. Of 135 indexed patients, 21 had colorectal biopsies. Colorectal biopsy specimens were abnormal in 7 of the 21 patients. Four patients had biopsy specimens resembling lymphocytic colitis, 2 patients had acute colitis, and another patient had both lymphocytic and acute colitis. No patients had collagenous colitis. Three of the patients with lymphocytic colitis and celiac-like changes of the small bowel never responded to a gluten-free diet and may represent a distinctive panintestinal disease for which the term "lymphocytic enterocolitis" with malabsorption is proposed.     

Morphological characterization of cellular and extracellular components of 7,12 dimethylbenz[a]anthracene induced melanoma tumours.

Subcutaneous tumours were induced in castrated golden Syrian hamsters by 7,12 dimethylbenz[a]anthracene (DMBA), an agent known to produce papillomas and carcinomas. The morphological characteristics of the cellular and extracellular constituents of the chemically-induced tumours were indicative of melanoma. Tumours were induced by three injections of DMBA into the jugular vein over a 3 month period. Dermal tumour development within the dorsal integument and groin region ultimately projected into the epidermis and occurred during the 3 month period subsequent to the last DMBA injection. Suspect melanoma tumours were excised and processed for light microscopic (LM) and transmission electron microscopic (TEM) studies. Histochemical staining methods facilitated the characterization of the differentiated tumour components in this hamster melanoma model. The model presented could allow observations from initial melanoma transformation events through advanced stages of metastasis within a window of 7 months.     

Molecular determinants of human uveal melanoma invasion and metastasis

The molecular analysis of cancer has benefited tremendously from the sequencing of the human genome integrated with the science of bioinformatics. Microarray analysis technology has the potential to classify tumors based on the differential expression of genes. In the current study, a collaborative, multidisciplinary approach was utilized to study the molecular determinants of human uveal melanoma invasion and metastasis. Uveal melanoma is considered the most common primary intraocular cancer in adults, resulting in the death of approximately 50% of patients affected. Unfortunately, at the time of diagnosis, many patients already harbor microscopic metastases, thus underscoring a critical need to identify prognostic markers indicative of metastatic potential. The investigative strategy consisted of isolating highly invasive vs. poorly invasive uveal melanoma cells from a heterogeneous tumor derived from cells that had metastasized from the eye to the liver. The heterogeneous tissue explant MUM-2 led to the derivation of two clonal cell lines: MUM-2B and MUM-2C. Further morphological and functional analyses revealed that the MUM-2B cells were epithelioid, interconverted (expressing mesenchymal and epithelial phenotypes) highly invasive, and demonstrated vasculogenic mimicry. The MUM-2C cells were spindle-like, expressed only a vimentin mesenchymal phenotype, poorly invasive, and were incapable of vasculogenic mimicry. The molecular analysis of the MUM-2B vs. the MUM-2C clones resulted in the differential expression of 210 known genes. Overall, the molecular signature of the MUM-2B cells resembled that of multiple phenotypes – similar to a pluripotent, embryonic-like genotype. Validation of select genes that were upregulated and down-regulated was conducted by semiquantitative RT-PCR measurement. This study provides a molecular profile that will hopefully lead to the development of new molecular targets for therapeutic intervention and possible diagnostic markers to predict the clinical outcome of patients with uveal melanoma. This revised version was published online in July 2006 with corrections to the Cover Date.