Comparison of postmortem whole-body contrast-enhanced microfocus computed tomography and high-field magnetic resonance imaging of human fetuses.

OBJECTIVE: Although fetal autopsy is generally recommended to confirm or refute the antemortem diagnosis, parental acceptance of the procedure has fallen over time, mainly due to its invasiveness. Contrast-enhanced microfocus CT (micro-CT) and high-field magnetic resonance imaging (HF-MRI, ≥ 3 Tesla) have both been suggested as non-invasive alternatives to conventional fetal autopsy for fetuses < 20 weeks of gestation. The aim of this study was to compare these two modalities in postmortem whole-body fetal imaging. METHODS: In this study, the imaging process and quality of micro-CT and HF-MRI were compared using both qualitative and quantitative assessments. For the qualitative evaluation, fetal anatomy experts scored 56 HF-MRI and 56 micro-CT images of four human fetuses aged 13-18 gestational weeks on two components: overall image quality and the ability to recognize and assess 21 anatomical structures. For the quantitative evaluation, participants segmented manually three organs with increasing complexity to assess interobserver variability. In addition, the signal-to-noise and contrast-to-noise ratios of five major organs were determined. RESULTS: Both imaging techniques were able to reach submillimeter voxel size. The highest resolution of micro-CT was 22 µm (isotropic), while the highest resolution of HF-MRI was 137 µm (isotropic). The qualitative image assessment form was sent to 45 fetal anatomy experts, of whom 36 (80%) responded. It was observed that micro-CT scored higher on all components of the qualitative assessment compared with HF-MRI. In addition, the quantitative assessment showed that micro-CT had lower interobserver variability and higher signal-to-noise and contrast-to-noise ratios. CONCLUSIONS: Our findings show that micro-CT outperforms HF-MRI in postmortem whole-body fetal imaging in terms of both quantitative and qualitative outcomes. Combined, these findings suggest that the ability to extract diagnostic information is greater when assessing micro-CT compared with HF-MRI images. We, therefore, believe that micro-CT is the preferred imaging modality as an alternative to conventional fetal autopsy for early gestation and is an indispensable tool in postmortem imaging services. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Reducing soft-tissue shrinkage artefacts caused by staining with Lugol's solution.

Diffusible iodine-based contrast-enhanced computed tomography (diceCT) is progressively used in clinical and morphological research to study developmental anatomy. Lugol's solution (Lugol) has gained interest as an effective contrast agent; however, usage is limited due to extensive soft-tissue shrinkage. The mechanism of Lugol-induced shrinkage and how to prevent it is largely unknown, hampering applications of Lugol in clinical or forensic cases where tissue shrinkage can lead to erroneous diagnostic conclusions. Shrinkage was suggested to be due to an osmotic imbalance between tissue and solution. Pilot experiments pointed to acidification of Lugol, but the relation of acidification and tissue shrinkage was not evaluated. In this study, we analyzed the relation between tissue shrinkage, osmolarity and acidification of the solution during staining. Changes in tissue volume were measured on 2D-segmented magnetic resonance and diceCT images using AMIRA software. Partial correlation and stepwise regression analysis showed that acidification of Lugol is the main cause of tissue shrinkage. To prevent acidification, we developed a buffered Lugol's solution (B-Lugol) and showed that stabilizing its pH almost completely prevented shrinkage without affecting staining. Changing from Lugol to B-Lugol is a major improvement for clinical and morphological research and only requires a minor adaptation of the staining protocol.

Novel imaging techniques to study postmortem human fetal anatomy: a systematic review on microfocus-CT and ultra-high-field MRI.

BACKGROUND: MRI and CT have been extensively used to study fetal anatomy for research and diagnostic purposes, enabling minimally invasive autopsy and giving insight in human fetal development. Novel (contrast-enhanced) microfocus CT (micro-CT) and ultra-high-field (≥ 7.0 T) MRI (UHF-MRI) techniques now enable micron-level resolution that combats the disadvantages of low-field MRI and conventional CT. Thereby, they might be suitable to study fetal anatomy in high detail and, in time, contribute to the postmortem diagnosis of fetal conditions. OBJECTIVES: (1) To systematically examine the usability of micro-CT and UHF-MRI to study postmortem human fetal anatomy, and (2) to analyze factors that govern success at each step of the specimen preparation and imaging. METHOD: MEDLINE and EMBASE were systematically searched to identify publications on fetal imaging by micro-CT or UHF-MRI. Scanning protocols were summarized and best practices concerning specimen preparation and imaging were enumerated. RESULTS: Thirty-two publications reporting on micro-CT and UHF-MRI were included. The majority of the publications focused on imaging organs separately and seven publications focused on whole body imaging, demonstrating the possibility of visualization of small anatomical structures with a resolution well below 100 µm. When imaging soft tissues by micro-CT, the fetus should be stained by immersion in Lugol's staining solution. CONCLUSION: Micro-CT and UHF-MRI are both excellent imaging techniques to provide detailed images of gross anatomy of human fetuses. The present study offers an overview of the current best practices when using micro-CT and/or UHF-MRI to study fetal anatomy for clinical and research purposes. KEY POINTS: • Micro-CT and UHF-MRI can both be used to study postmortem human fetal anatomy for clinical and research purposes. • Micro-CT enables high-resolution imaging of fetal specimens in relatively short scanning time. However, tissue staining using a contrast solution is necessary to enable soft-tissue visualization. • UHF-MRI enables high-resolution imaging of fetal specimens, without the necessity of prior staining, but with the drawback of long scanning time.

[Supplementary optical techniques for the detection of nonmuscle invasive bladder cancer]. / Unterstützende optische Verfahren zur Detektion nicht-muskelinvasiver Blasentumoren.

White light cystoscopy (WL) is the gold standard for the detection of bladder cancer. It can be performed using a rigid or flexible urethrocystoscope. With the more recent introduction of high definition (HD) techniques, WL cystoscopy has been decisively improved. Supplementary optical techniques are also used to improve the detection of bladder cancer. Among these are photodynamic diagnosis (PDD), narrow-band imaging (NBI), S­technologies of IMAGE1 S, optical coherence tomography (OCT), confocal laser endomicroscopy (CLE), and Raman spectroscopy. The aim of the present work is to introduce the techniques and to discuss their current role and future potential in the detection of bladder cancer.

Uranium-series disequilibrium dating of secondary uranium ore from the south Eastern Desert of Egypt.

The secondary uranium ore of Um Ara mining area, south Eastern Desert of Egypt, is composed mainly of uranophane and beta-uranophane. They occur in the oxidized zone as idiomorphic crystals filling cavities and as coatings on the fracture surfaces of the alkali-feldspar and albitized granites. The activity ratios 234U/238U and 230Th/234U of the secondary uranium ore and host rocks indicate that there were two main phases of uranium mobility in recent geological time. An earlier precipitation of uranium from solutions forming the secondary ore and a subsequent mobilization resulted in adsorption of uranium to the host granitic rocks. The 230Th/234U age of secondary uranium ore varies from (50 +/- 10) to (159 +/- 69/-45) ka whereas, the age of uranium adsorption to the rocks ranges from (18 +/- 6) to (38 +/- 5) ka. The time of secondary uranium ore precipitation can be attributed to the Saharan II pluvial period which prevailed in Egypt during humid oxygen isotope climatic stage 5. The later uranium mobility and subsequent adsorption by the rocks took place during Kubbaniyan and Nabtian pluvial periods that coincided with oxygen isotope stages 3 and 1, respectively.

Intensity encoding in unsupervised neural nets.

The requirement of input vector normalisation in unsupervised neural nets results in a loss of information about the intensity of the signal contained in the input datastream. We show through a simple algebraic analysis that the introduction of an additional input channel encoding the root-mean-square intensity in the signals cannot restore this information if the input vectors have to be, nevertheless, all of the same length. We suggest an alternative method of encoding the input vectors where each of the input channels is split into two components in such a way that the resultant input vector is then of fixed length and retains information of the intensity in the signals. We further demonstrate, by using synthetic data, that a Kohonen Net is capable of forming topological maps of signals of different intensity, where an adjacency relationship is maintained both among the signals of the same frequency composition at different intensities and between signals of different frequency compositions at the same intensity. A second experiment reported here shows the same behaviour for less artificial inputs (based on a cochlear model) and additionally demonstrates that the trained network can respond appropriately to signals not previously encountered.

Lumbar puncture in the evaluation of possible asymptomatic congenital syphilis in neonates.

OBJECTIVE: To evaluate the usefulness of lumbar puncture (LP) in the initial evaluation of symptom-free infants for congenital syphilis. STUDY DESIGN: We retrospectively studied infants who had successful LPs and were born to untreated or inadequately treated seropositive women between 1990 and 1993 in two hospitals in Washington, D.C. We identified 329 such symptom-free infants (syphilis group). The cerebrospinal fluid (CSF) VDRL was reactive in two (0.6%) infants. The CSF leukocyte and protein concentrations of these infants were compared with those in 84 symptom-free control infants who were born to seronegative women and who had LPs performed in 1993 to rule out sepsis because of associated risk factors. Control infants had negative results for bacterial cultures (CSF and blood) and bacterial antigen tests (CSF and urine). RESULTS: Thirty control subjects and 67 infants in the syphilis group had traumatic taps (CSF erythrocytes > 500 x 10(6)/L), and hence were excluded from the analysis of cell count and proteins. Birth weights and gestational ages were similar in both groups. The CSF leukocyte and protein values were similar in the syphilis group and in control infants: mean CSF leukocytes 7.7 x 10(6)/L (mean 7.7/mm3, range 0 to 57/mm3, SD 8.8) versus 6.9 x 10(6)/L (mean 6.9/mm3, range 0 to 31/mm3, SD 7), p = 0.5, and mean protein concentration 981 mg/L (range 270 to 2280 mg/L, SD 376) versus 936 mg/L (range 360 to 1750 mg/L, SD 368), p = 0.96, respectively. The combination of CSF leukocyte values > 5 x 10(6)/L (> 5/mm3) or protein values > 400 mg/L (> 40 mg/dl) was found in 97.8% of the infants in the syphilis group, compared with 95.3% of the control group. CONCLUSION: Because of the low yield of reactive CSF VDRL and the similar CSF leukocyte and protein values in the syphilis group and the control infants, the role of routine LP in the initial evaluation of symptom-free infants for congenital syphilis should be reconsidered.

Expression of the oxytocin and vasopressin genes in human and baboon gonadal tissues.

A variety of molecular techniques were used to search human and baboon gonadal tissues for evidence of transcription of the genes for the peptide hormones oxytocin and vasopressin. Only a highly sensitive assay based on a modification of the polymerase chain reaction succeeded in detecting mRNA copies of the oxytocin gene in both human and baboon corpus luteum. Vasopressin gene transcription was not detected in human testis and corpus luteum and was found only once in four different experiments in baboon corpus luteum. Evidence for oxytocin gene transcription in the human testis was found in three of five experiments. The method employed and subsequent sequence analysis of the polymerase products verified the presence of oxytocin mRNA with normal hypothalamic-type exonic structure in primate corpus luteum. Nevertheless, the very low levels of mRNA present are unlikely to support other than local functions for the encoded nonapeptide hormones.

Primary amenorrhea associated with hirsutism, acanthosis nigricans, dermoid cysts of the ovaries and a new type of insulin resistance.

We describe a 15 1/2 year old presenting with primary amenorrhea, hirsutism, acanthosis nigricans and insulin resistance. Ovarian vein catheterization studies revealed bilateral excess plasma testosterone and androstenedione secretion, and at surgery multiple dermoid cysts of both ovaries were found in association with polycystic ovaries. The suggestion that the dermoid cysts may be causative in the evolution of the polycystic ovarian disease has been made. The mechanism of the insulin resistance appears to be at the post receptor level. The acanthosis nigricans diminished following surgery with normalization of the plasma androgens.