Radiomics in diffusion data: a test-retest, inter- and intra-reader DWI phantom study.

AIM: The aim of this study was to evaluate the robustness of radiomics features of a MRI (magnetic resonance imaging) phantom in quantitative diffusion-weighted imaging (DWI) and depending on the image resolution. MATERIALS AND METHODS: Scanning of an in-house developed DWI phantom was performed at a 1.5 T MRI scanner (Magnetom AERA, Siemens, Erlangen, Germany) using an echo planar imaging (EPI) DWI sequence (b=0,500,1,000 s/mm2) with low (3×3 mm2) and high (2×2 mm2) image resolutions. Scans were repeated after phantom repositioning to evaluate retest reliability. Radiomics features were extracted after semi-automatic segmentation and standardised pre-processing. Intra-/interobserver reproducibility and test-retest robustness were assessed using intraclass correlation coefficients (ICC). Differences were tested with non-parametric Wilcoxon's signed-rank and Friedman's test (p < 0.05) with Dunn's post-hoc analysis. RESULTS: Test-retest ICC was overall high with >0.90 for 39/46 radiomics features in all sequences/resolutions. Decreased test-retest ICCs were pronounced for conventional Min-value (overall ICC=0.817), and grey-level zone length matrix (GLZLM) features Short-Zone Emphasis (SZE) and Short-Zone Low Grey-level Emphasis (SZLGE) (for both overall ICC=0.927). Test-retest reproducibility was significantly different between b=500, 1,000 and apparent diffusion coefficient (ADC) (mean 0.975±0.050, 0.974±0.051 and 0.966±0.063), which remained significant after post-hoc analysis between b=1,000 and ADC (p = 0.022). ICCs were not significantly different between resolutions of 2×2 and 3×3 mm2 regarding b=500 (mean: 0.977±0.052 and 0.974±0.049, p = 0.612), b=1,000 (mean: 0.973±0.059 and 0.974±0.054, p = 0.516), and ADC (mean: 0.972±0.049 and 0.955±0.101, p = 0.851). Inter- and intra-observer reliability was consistently high for all sequences (overall mean 0.992±0.021 and 0.990±0.028). CONCLUSION: Under ex-vivo conditions, DWI provided robust radiomics features with those from ADC being slightly less robust than from raw DWI (b=500, 1,000 s/mm2). No significant difference was detected for different resolutions. Although, ex-vivo reliability of DWI radiomics features was high, no implications can be made regarding in-vivo analyses.

What remains after transient global amnesia (TGA)? An ultra-high field 7 T magnetic resonance imaging study of the hippocampus.

BACKGROUND AND PURPOSE: The aim was to study whether ultra-high field 7 T magnetic resonance imaging (MRI) can demonstrate chronic focal defects in the hippocampus corresponding to the former acute diffusion-weighted imaging (DWI) lesions and to assess chronic T2-hyperintense hippocampal lesion load in transient global amnesia (TGA) patients. METHODS: Follow-up of 7 T MRI of the hippocampus was performed in 13 patients with documented hippocampal DWI lesions (detected via 3 T MRI) after acute TGA. The location of the DWI lesions was transformed to 7 T T2 images after data co-registration. Additionally, the T2-hyperintense lesion load was estimated in each patient and compared with that of 13 healthy controls. RESULTS: Magnetic resonance imaging (7 T) was performed after a median of 4 months. No structural abnormality at the site of the previous TGA lesion was observed in any case. None of the controls showed DWI lesions. There was no significant difference between patients and controls concerning the number (P = 0.67) or volume (P = 0.45) of T2-hyperintense hippocampal lesions. CONCLUSIONS: Diffusion-weighted imaging lesions in patients with TGA do not provoke any visible sequelae and do not result in hippocampal cavities. The occurrence of incidental hippocampal T2 lesions after TGA is not more frequent than in controls.

Dual left anterior descending coronary artery (type III) and the presence of myocardial bridges: a post-mortem examination.

An observational examination of the heart was performed in the Department of Anatomy, during the routine autopsy of an 89-year-old man. The heart was fixed in 10% formalin and an analysis of arterial vasculature was performed (used morphometric abbreviations below [mm]: L - length; D - diameter of origin). Trifurcation of the left main coronary artery (L = 17.4; D = 8.1) was observed during the study, which originated in the left aortic sinus and was followed by three branches: proper left anterior descending artery (pLAD; L = 11.2; D = 7.4), intermediate branch (L = 98.6; D = 3.5) and left circumflex artery (L = 104.2; D = 4.9), respectively. In the pLAD division, there was noted LAD1 (long) which was running in the interventricular septum (L = 32.2) and further in the subepicardial segment (L = 109.3) in the anterior interventricular groove towards the apex (AC) (LAD1; L = 141.4; D = 6.3) and LAD2 (short) running subepicardial in the anterior interventricular groove in the AC direction (LAD2; L = 68.4; D = 3.2). Four diagonal branches (DB) and 9 septal perforators (SP) were observed in the course of LAD1; regarding the LAD2 there were 6 SP only. It is worth noting that the first SP supplying the interventricular septum came from LAD2. Another interesting aspect of the observation was the occurrence of 4 myocardial bridges on the LAD1, LAD2, DB1 arteries and on the second obtuse marginal branch (OM2), respectively. This case describes a rare anatomical anomaly of the LAD course and reminds clinicians of the need for careful planning of cardiac surgeries and percutaneous interventions on the coronary arteries.

Rare morphological variants of the bones: epicondylar processes, metopic suture and Wormian bones in XVIII century skeleton.

BACKGROUND: Analysis of the female skeleton from the 18th century revealed a collection of morphological changes. MATERIALS AND METHODS: Anthropological evaluation and dental X-ray techniques allowed the age to be determined at 12-13 years. RESULTS: The distal parts of the both humerus bones had distinct, supracondylar processes of about 5 mm at the medial-lateral surface. The frontal bone had a well-preserved metopic suture along the entire length of the squama. There were also two Wormian bones (Inca bones), asymmetrical mastoid foramen, and only left non-obliterated condylar canal. CONCLUSIONS: The skull measurements allowed the cranial index to be determined - 93.5 (brachycephalia) and height-length index - 98.6 (akrocephalus). Moreover, X-ray analysis of incomplete dentition was made.

[Diffusion-weighted imaging-diagnostic supplement or alternative to contrast agents in early detection of malignancies?] / Diffusionsbildgebung ­ diagnostische Erweiterung oder Ersatz von Kontrastmitteln in der Früherkennung von Malignomen?

Medical research in the field of oncologic imaging diagnostics using magnetic resonance imaging increasingly includes diffusion-weighted imaging (DWI) sequences. The DWI sequences allow insights into different microstructural diffusion properties of water molecules in tissues depending on the sequence modification used and enable visual and quantitative analysis of the acquired imaging data. In DWI, the application of intravenous gadolinium-containing contrast agents is unnecessary and only the mobility of naturally occurring water molecules in tissues is quantified. These characteristics predispose DWI as a potential candidate for emerging as an independent diagnostic tool in selected cases and specific points in question. Current clinical diagnostic studies and the ongoing technical developments, including the increasing influence of artificial intelligence in radiology, support the growing importance of DWI. Especially with respect to selective approaches for early detection of malignancies, DWI could make an essential contribution as an eligible diagnostic tool; however, prior to discussing a broader clinical implementation, challenges regarding reliable data quality, standardization and quality assurance must be overcome.

Four left renal arteries - a rare variant of kidney arterial supply.

We describe the arterial supply of a human kidney harvested post-mortem from a 75-year-old female volunteer body donor. The kidney was analysed with con- trast-enhanced computed tomography (CT), and corrosion casting was used to reveal the kidney's angio-architecture. In the left kidney, we observed four renal arteries, each originating directly from the abdominal aorta. Three renal arteries, including the main renal artery, coursed through the renal hilum, and the fourth renal artery reached the lower kidney pole. The supply areas of each of the four renal arteries were analysed with a three-dimensional reconstruction of CT images and with corrosion casting. There were no clear boundaries between the areas supplied by the four renal arteries because their branches overlapped in most kidney segments.

Diffusion-weighted breast imaging.

Magnetic resonance imaging (MRI) of the breast represents one of the most sensitive imaging modalities in breast cancer detection. Diffusion-weighted imaging (DWI) is a sequence variation introduced as a complementary MRI technique that relies on mapping the diffusion process of water molecules thereby providing additional information about the underlying tissue. Since water diffusion is more restricted in most malignant tumors than in benign ones owing to the higher cellularity of the rapidly proliferating neoplasia, DWI has the potential to contribute to the identification and characterization of suspicious breast lesions. Thus, DWI might increase the diagnostic accuracy of breast MRI and its clinical value. Future applications including optimized DWI sequences, technical developments in MR devices, and the application of radiomics/artificial intelligence algorithms may expand the potential of DWI in breast imaging beyond its current supplementary role.

Maximum intensity breast diffusion MRI for BI-RADS 4 lesions detected on X-ray mammography.

AIM: To investigate an abbreviated, contrast-agent free diffusion-weighted (DW) breast magnetic resonance imaging (MRI) protocol that provides a single image for the radiologist to read in order to non-invasively examine Breast Imaging-Reporting and Data System (BI-RADS) 4 lesions detected using breast cancer screening X-ray mammography. MATERIALS AND METHODS: This retrospective evaluation within a institutional review board-approved, prospective study included 115 women (mean 57 years, range 50-69 years) with BI-RADS 4 findings on X-ray mammography and indication for biopsy over a period of 15 months. Full diagnostic breast MRI (FDP) was performed prior to biopsy (1.5 T). Maximum intensity breast diffusion (MIBD) images were generated from DW images (b = 1,500 mm/s2, 3 mm section thickness) of the breast. MIBD and T2-weighted (T2W) images were read by two radiologists and compared to the diagnostic accuracy of an expert reading of the FDP with histopathology as the reference standard. The acquisition time of MIBD and T2W MRI was about 7 minutes. RESULTS: MIBD MRI provided a diagnostic accuracy of 87.93% (95% confidence interval [CI]: 80.58-93.24%) for R1 and 89.66% (95% CI: 82.63-94.54%) for R2. Expert reading of the FDP revealed a similar accuracy of 86.2% (95% CI: 78.67-91.43%). The positive predictive value (PPV) could be increased from 36.2% (95% CI: 28.02-45.28; X-ray mammography alone) to a mean PPV of 80.89% (R1 79.17%, R2 82.16%) using MIBD MRI. Mean reading time was 30 seconds (25%/75 percentile 24.5-41.25). CONCLUSIONS: MIBD MRI might be of supplemental value if added to the work-up of BI-RADS 4 X-ray mammography screening findings. MIBD MRI might help reduce the false-positive rate prior to biopsy for reference lesions at only limited expense of measurement and reading time.

Adrenergic and cholinergic innervation of the atrioventricular valves in chinchilla (Chinchilla laniger).

The arrangement of autonomic fibres was studied in the cardiac atrioventricular valves of small chinchillas. The dissected valves were stained entirely using the modified histochemical acetylcholine esterase technique (AChE) and the SPG-De la Torre method. Double immunocytochemical staining was also used for the expression of vesicular acetylcholine transporter (VAChT) and dopamine beta hydroxylase (DBH). The study showed the presence of both cholinergic and adrenergic fibres, forming a kind of network on all cusps of both valves. The adrenergic network is always more strongly represented than the cholinergic network. The cholinergic nerve network of the "parietal" part formed mainly the parallel arrangement. As we move towards the free parts of the cusps, the arrangement becomes netted and radiant. The adrenergic fibres formed only the netted arrangement, which was the most dense in the peripheral (parietal) part of the cusps. Some of the fibres in the vicinity of tendinous cords extended as far as the papillary muscles. Double immunocytochemical tests confirmed the presence and distribution of DBH- and VAChT-positive fibres. Some fibres (especially within the tendinous cords) show VAChT and DBH colocalisation.

[Selected clinically established and scientific techniques of diffusion-weighted MRI. In the context of imaging in oncology]. / Ausgewählte klinisch etablierte und wissenschaftliche Techniken der diffusionsgewichteten MRT. Im Kontext der onkologischen Bildgebung.

BACKGROUND: Diffusion-weighted imaging (DWI) is a magnetic resonance imaging (MRI) technique that was established in the clinical routine primarily for the detection of brain ischemia. In the past 15 years its clinical use has been extended to oncological radiology, as tumor and metastases can be depicted in DWI due to their hypercellular nature. PRINCIPLES: The basis of DWI is the Stejskal-Tanner experiment. The diffusion properties of tissue can be visualized after acquisition of at least two diffusion-weighted series using echo planar imaging and a specific sequence of gradient pulses. CLINICAL APPLICATIONS: The use of DWI in prostate MRI was reported to be one of the first established applications that found its way into internationally recognized clinical guidelines of the European Society of Urological Radiology (ESUR) and the prostate imaging reporting and data system (PI-RADS) scale. Due to recently reported high specificity and negative predictive values of 94% and 92%, respectively, its regular use for breast MRI is expected in the near future. Furthermore, DWI can also reliably be used for whole-body imaging in patients with multiple myeloma or for measuring the extent of bone metastases. OUTLOOK: New techniques in DWI, such as intravoxel incoherent motion imaging, diffusion kurtosis imaging and histogram-based analyses represent promising approaches to achieve a more quantitative evaluation for tumor detection and therapy response.

Autonomic cardiac nerves: literature review.

The aim of this paper was to summarise the knowledge about the autonomic cardiac innervation. It is generally known, that the cardiac nervous system consists of nerve plexoganglionic structures located mostly around the strategic regions of the heart. They consist of two main types of components: parasympathetic neurons, which exert an inhibitory effect, and sympathetic postganglionic nerve fibres, which stimulate the cardiac conduction system, and myocardial cells. However, many authors describe that cardiac ganglia contain various populations of neurons. The largest group are classical cholinergic neurons. The second group of cardiac neurons are cells of dual, cholinergic-adrenergic character. There is also subpopulation of small intensely fluoroscent cells of typically adrenergic phenotype. Moreover, many authors indicated the presence of various neurotransmitters in various combinations. In this way, the neurons in cardiac ganglia are a neurochemical complex beyond the classical vision of parasympathetic ganglia.

Extrahepatic biliary tract in chinchilla (Chinchilla laniger, Molina).

The aim of the study was the macromorphological analysis of extrahepatic biliary tract in chinchilla (Chinchilla laniger Molina). Bile ducts, the gall bladder and portal vein were injected with coloured latex. Using the technique of dissection, bile ducts were isolated from the liver lobes. It was found that the cystic duct in this species is rarely single. Hepatic ducts form a system of multiple anastomosing structures running in the hepatoduodenal ligament. Many bile duct openings were observed in the duodenal papilla. The results confirm wide variations of the biliary tract in mammals and may be important for comparative analysis of the morphological differentiation of these structures in small mammals.

Contrast-enhanced ultrasound monitoring of perfusion changes in hepatic neuroendocrine metastases after systemic versus selective arterial 177Lu/90Y-DOTATOC and 213Bi-DOTATOC radiopeptide therapy.

AIM: Radiopeptide therapy with beta emitter labeled (177)Lu/(90)Y- DOTA(0)-Phe(1)-Tyr(3)-octreotide (DOTATOC) and more recently also alpha emitting (213)Bi-DOTATOC are promising new treatments for neuroendocrine tumors. No early predictors for treatment response have been recognized and tumor-shrinkage after radiation therapy appears slowly. In some solid tumors a decline in tumor perfusion was found predictive of final treatment response but the gold standard multiphase computed tomography (CT) has a high radiation burden. Therefore we evaluated the ability of contrast-enhanced ultrasound (CEUS) to evaluate tumor perfusion as a response criteria. MATERIALS AND METHODS: 14 patients with hepatic neuroendocrine tumor (NET) metastases were enrolled in the retrospective study. Eleven patients were treated with beta-emitting (177)Lu/(90)Y-DOTATOC, either intravenous (i.v.) (n = 5) or intra-arterial (i.a.) (n = 6) and three patients received alpha-emitting (213)Bi-DOTATOC (i.a.). CEUS and contrast-enhanced CT (CE-CT) were performed before and 3 months after treatment. RESULTS: CE-CT and CEUS presented comparable results in the baseline study and in the assessment of perfusion changes due to the different treatment regimes. A therapy related decrease in tumor perfusion is an early predictor of longterm morphologic response. CONCLUSION: CEUS is available and radiation free technique which showed comparable results for perfusion and diameter of liver metastases compared to CE-CT. Intensity reduction in an arterial phase CEUS can be seen as a positive sign indicating long term tumor response to treatment. Therefore CEUS may be considered as an imaging modality for monitoring early treatment after focal alpha and beta targeted therapy.

Quantification of pulmonary microcirculation by dynamic contrast-enhanced magnetic resonance imaging: comparison of four regularization methods.

Tissue microcirculation can be quantified by a deconvolution analysis of concentration-time curves measured by dynamic contrast-enhanced magnetic resonance imaging. However, deconvolution is an ill-posed problem, which requires regularization of the solutions. In this work, four algebraic deconvolution/regularization methods were evaluated: truncated singular value decomposition and generalized Tikhonov regularization (GTR) in combination with the L-curve criterion, a modified LCC (GTR-MLCC), and a response function model that takes a-priori knowledge into account. To this end, dynamic contrast-enhanced magnetic resonance imaging data sets were simulated by an established physiologically reference model for different signal-to-noise ratios and measured on a 1.5-T system in the lung of 10 healthy volunteers and 20 patients. Analysis of both the simulated and measured dynamic contrast-enhanced magnetic resonance imaging datasets revealed that GTR in combination with the L-curve criterion does not yield reliable and clinically useful results. The three other deconvolution/regularization algorithms resulted in almost identical microcirculatory parameter estimates for signal-to-noise ratios > 10. At low signal-to-noise ratios levels (<10) typically occurring in pathological lung regions, GTR in combination with a modified L-curve criterion approximates the true response function much more accurately than truncated singular value decomposition and GTR in combination with response function model with a difference in accuracy of up to 76%. In conclusion, GTR in combination with a modified L-curve criterion is recommended for the deconvolution of dynamic contrast-enhanced magnetic resonance imaging curves measured in the lung parenchyma of patients with highly heterogeneous signal-to-noise ratios.

[Introduction to the basic principles and techniques of diffusion-weighted imaging]. / Einführung in die Grundlagen und Techniken der Diffusionsbildgebung.

This article gives an overview of the many different technical aspects of diffusion-weighted imaging and a review of the physical and mathematical background. Specific terms, such as free and restricted diffusion are introduced and elucidated. The measurement of diffusion by magnetic resonance imaging (MRI) and which phenomena can occur are described. Finally, an overview of current developments in diffusion imaging and its application in research is presented.

A hybrid breath hold and continued respiration-triggered technique for time-resolved 3D MRI perfusion studies in lung cancer.

PURPOSE: Assessment of lung cancer perfusion is impaired by respiratory motion. Imaging times for contrast agent wash-out studies often exceed breath hold capabilities, and respiration triggering reduces temporal resolution. Temporally resolved volume acquisition of entire tumors is required to assess heterogeneity. Therefore, we developed and evaluated an MR measurement technique that exceeds a single breath hold, and provides a variable temporal resolution during acquisition while suspending breath-dependent motion. MATERIALS AND METHODS: 20 patients with suspected lung cancer were subjected to perfusion studies using a spoiled 3D gradient echo sequence after bolus injection of 0.07 mmol/kg body weight of Gd-DTPA. 10 acquisitions in expiratory breath hold were followed by 50 navigator-triggered acquisitions under free breathing. Post-processing allowed for co-registration of the 3D data sets. An ROI-based visualization of the signal-time curves was performed. RESULTS: In all cases motion-suspended, time-resolved volume data sets (40 x 33 x 10 cm(3), voxel size: 2.1 x 2.1 x 5.0 mm(3)) were generated with a variable, initially high temporal resolution (2.25 sec) that was synchronized with the breath pattern and covered up to 8 1/2 min. In 7 / 20 cases a remaining offset could be reduced by rigid co-registration. The tumors showed fast wash-in, followed by rapid signal decay (8 / 20) or a plateau. CONCLUSION: The feasibility of a perfusion study with hybrid breath hold and navigator-triggered time-resolved 3D MRI which combines high initial temporal resolution during breath hold with a long wash-out period under free breathing was demonstrated.

Arteries supplying the base of the brain in the Mongolian gerbil (Meriones unguiculatus).

Using stained acryl latex injected techniques the arteries of the base of the brain in the Mongolian gerbil (Meriones unguiculatus) were studied. The brain of the Mongolian gerbil is supplied with blood by even internal carotid arteries and odd basilar artery. The branches of the internal carotid arteries supply the forebrain and interbrain. They form the arterial circle at the base of the brain. The basilar artery is a source of blood for the midbrain and hindbrain. In this species, except one case, the opened type at the back side of arterial circle was found. The posterior communicating arteries between basilar artery and internal carotid arteries were not observed.

Topography of arterial circle of the brain in Egyptian spiny mouse (Acomys cahirinus, Desmarest).

Using stained acryl latex-injected techniques, the arterial circle of the brain in Acomys cahirinus Desmarest was studied. Results revealed an important individual variability of investigated structure. Three morphological variants were found: (1) the lack of typical arterial circle--opened in front and the back side, (2) partial opened at the back side, (3) completely closed arterial circle. This finding is opposed to many species of mammals, including rodents, and especially laboratory mouse. In our point of view, it seems to be a specific character.

A comparative study on cardiac ganglia in midday gerbil, Egyptian spiny mouse, chinchilla laniger and pigeon.

Using the thiocholine method and histological techniques, the topography and morphology of cardiac ganglia in midday gerbil, Egyptian spiny mouse, chinchilla laniger and pigeon were studied. The results demonstrated that cardiac ganglia in all investigated species are embedded in epicardial fat. They formed plexo-ganglionic structures. Each of them composed of many ganglia (from seven up to 36) different in size and shape, and interconnected by fascicles of nerve fibres. Comparative analysis showed that the density of neural network and cell aggregations was different in individual species. The richest plexo-ganglionic structure was in pigeon. It was organized in three plexo-ganglia with an average of 30 ganglia. The largest one was located along the anterior interventricular sulcus. The cardiac ganglia of investigated mammals were localized mainly on the epicardium of atria; in Egyptian spiny mouse and chinchilla laniger on the ventral surface of right atrium, but in midday gerbil on the dorsal surface of left atrium. Moreover, in midday gerbil and Egyptian spiny mouse the little plexo-ganglionic structure on the ventricle were noticed. Additionally, in midday gerbil the single nerve cells might be observed between cardiac muscle of atria. It can be said that, the strongly developed cardiac plexus in pigeon is probably connected with his behaviour and functional properties of the heart. The arrangement of neurones in cardiac ganglia of all examined mammals was uniform over the whole surface of the sections, while in the pigeon, neurones were located mainly in the peripheral part of the ganglion.

The comparative analysis of the myenteric plexus in pigeon and hen.

Using the thiocholine method and histological techniques the myenteric plexuses of pigeon and hen were studied. Investigations revealed the presence of a nervous network in the wall of the small intestine of both animals. It consists of many nerve fibres crossing each other and creating meshes in a variety of shapes. The density of the network was different according to the species and to the parts of intestine. The myenteric plexus from the pigeon's duodenum is thicker (3.7-fold) than in the remaining part of the small intestine; in the hen this is approximately 2.2-fold thicker. The meshes of the duodenum in both species are smaller than in the jejunum and ileum. The results of histological investigations showed different localization of myenteric plexuses; in pigeon in the space between the circular and longitudinal muscle layers, and in hen within the circular muscle.