Computer-aided anatomy recognition in intrathoracic and -abdominal surgery: a systematic review.

BACKGROUND: Minimally invasive surgery is complex and associated with substantial learning curves. Computer-aided anatomy recognition, such as artificial intelligence-based algorithms, may improve anatomical orientation, prevent tissue injury, and improve learning curves. The study objective was to provide a comprehensive overview of current literature on the accuracy of anatomy recognition algorithms in intrathoracic and -abdominal surgery. METHODS: This systematic review is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Pubmed, Embase, and IEEE Xplore were searched for original studies up until January 2022 on computer-aided anatomy recognition, without requiring intraoperative imaging or calibration equipment. Extracted features included surgical procedure, study population and design, algorithm type, pre-training methods, pre- and post-processing methods, data augmentation, anatomy annotation, training data, testing data, model validation strategy, goal of the algorithm, target anatomical structure, accuracy, and inference time. RESULTS: After full-text screening, 23 out of 7124 articles were included. Included studies showed a wide diversity, with six possible recognition tasks in 15 different surgical procedures, and 14 different accuracy measures used. Risk of bias in the included studies was high, especially regarding patient selection and annotation of the reference standard. Dice and intersection over union (IoU) scores of the algorithms ranged from 0.50 to 0.98 and from 74 to 98%, respectively, for various anatomy recognition tasks. High-accuracy algorithms were typically trained using larger datasets annotated by expert surgeons and focused on less-complex anatomy. Some of the high-accuracy algorithms were developed using pre-training and data augmentation. CONCLUSIONS: The accuracy of included anatomy recognition algorithms varied substantially, ranging from moderate to good. Solid comparison between algorithms was complicated by the wide variety of applied methodology, target anatomical structures, and reported accuracy measures. Computer-aided intraoperative anatomy recognition is an upcoming research discipline, but still at its infancy. Larger datasets and methodological guidelines are required to improve accuracy and clinical applicability in future research. TRIAL REGISTRATION: PROSPERO registration number: CRD42021264226.

Resting-state functional connectivity of ventral parietal regions associated with attention reorienting and episodic recollection.

In functional neuroimaging studies, ventral parietal cortex (VPC) is recruited by very different cognitive tasks. Explaining the contributions of VPC to these tasks has become a topic of intense study and lively debate. Perception studies frequently find VPC activations during tasks involving attention-reorienting, and memory studies frequently find them during tasks involving episodic recollection. According to the Attention to Memory (AtoM) model, both phenomena can be explained by the same VPC function: bottom-up attention. Yet, a recent functional MRI (fMRI) meta-analysis suggested that attention-reorienting activations are more frequent in anterior VPC, whereas recollection activations are more frequent in posterior VPC. Also, there is evidence that anterior and posterior VPC regions have different functional connectivity patterns. To investigate these issues, we conducted a resting-state functional connectivity analysis using as seeds the center-of-mass of attention-reorienting and recollection activations in the meta-analysis, which were located in the supramarginal gyrus (SMG, around the temporo-parietal junction-TPJ) and in the angular gyrus (AG), respectively. The SMG seed showed stronger connectivity with ventrolateral prefrontal cortex (VLPFC) and occipito-temporal cortex, whereas the AG seed showed stronger connectivity with the hippocampus and default network regions. To investigate whether these connectivity differences were graded or sharp, VLPFC and hippocampal connectivity was measured in VPC regions traversing through the SMG and AG seeds. The results showed a graded pattern: VLPFC connectivity gradually decreases from SMG to AG, whereas hippocampal connectivity gradually increases from SMG to AG. Importantly, both gradients showed an abrupt break when extended beyond VPC borders. This finding suggests that functional differences between SMG and AG are more subtle than previously thought. These connectivity differences can be explained by differences in the input and output to anterior and posterior VPC regions, without the need of postulating markedly different functions. These results are as consistent with integrative accounts of VPC function, such as the AtoM model, as they are with models that ascribe completely different functions to VPC regions.

Explaining the encoding/retrieval flip: memory-related deactivations and activations in the posteromedial cortex.

The posteromedial cortex (PMC) is strongly linked to episodic memory and age-related memory deficits. The PMC shows deactivations during a variety of demanding cognitive tasks as compared to passive baseline conditions and has been associated with the default-mode of the brain. Interestingly, the PMC exhibits opposite levels of functional MRI activity during encoding (learning) and retrieval (remembering), a pattern dubbed the encoding/retrieval flip (E/R-flip). Yet, the exact role of the PMC in memory function has remained unclear. This review discusses the possible neurofunctional and clinical significance of the E/R-flip pattern. Regarding neurofunctional relevance, we will review four hypotheses on PMC function: (1) the internal orienting account, (2) the self-referential processing account, (3) the reallocation account, and (4) the bottom-up attention account. None of these accounts seem to provide a complete explanation for the E/R-flip pattern in PMC. Regarding clinical relevance, we review work on aging and Alzheimer's disease, indicating that amyloid deposits within PMC, years before clinical memory deficits become apparent. High amyloid burden within PMC is associated with detrimental influences on memory encoding, in particular, the attenuation of beneficial PMC deactivations. Finally, we discuss functional subdivisions within PMC that help to provide a more precise picture of the variety of signals observed within PMC. Collective data from anatomical, task-related fMRI and resting-state studies all indicate that the PMC is composed of three main regions, the precuneus, retrosplenial, and posterior cingulate cortex, each with a distinct function. We will conclude with a summary of the findings and provide directions for future research.

Experience-dependent alterations in conscious resting state activity following perceptuomotor learning.

In monkeys and rats, neural activity patterns during learning are reactivated during subsequent periods of rest or sleep. According to the reactivation-consolidation account, this process underlies the consolidation of memories. Brain imaging studies have extended these findings to humans during sleep, but not yet, during rest. Here, we show that learning-related reactivation also occurs in humans during rest. During functional MRI-scanning, participants trained on a perceptuomotor task flanked by rest periods. During training, we found robust activity in the superior parietal cortex. During post-training rest, this same area reactivated. We also found a link between parietal reactivation and learning. Activity in superior parietal cortex was associated with learning during training, and a control group that did not train on the perceptuomotor task did not show any difference between the pre- and post-training rest blocks in this region. These findings indicate that, during rest, reactivation also occurs in humans. This process may contribute to consolidation of perceptuomotor memories.

Dissociating the "retrieval success" regions of the brain: effects of retrieval delay.

There is abundant evidence that the hippocampal formation critically supports episodic memory retrieval, the remembering of episodes including contextual details. Yet, a group of other brain regions has also been consistently implicated in successful episodic retrieval. This retrieval success network (RSN) includes the posterior midline region, medial prefrontal cortex (mPFC), and posterior parietal cortex (PPC). Despite these consistent findings, the functional roles of the RSN regions remain poorly understood. Given that vivid remembering leads to high-confidence retrieval decisions, it is unclear whether activity in these regions reflects episodic long-term memory, or is merely associated with retrieval confidence. In order to distinguish between these alternatives, we manipulated study-test delays within the context of a continuous recognition task during fMRI-scanning. The design was based on previous evidence indicating that retrieval at short delays is easier leading to high-evidence mnemonic decisions, whereas retrieval at longer delays is more difficult but also more hippocampus-dependent. Confirming previous findings, we found that retrieval decisions at short delays were more accurate and faster, and that the hippocampus showed greater activity at longer delays. Within the other RSN regions, we found three distinct activation patterns as a function of delay. Similar to the hippocampus, the retrosplenial cortex showed increased activity as a function of retrieval delay. Dorsal PPC and the precuneus showed decreased activity. Finally, the posterior cingulate, medial PFC and ventral PPC showed a V-shaped pattern. These findings support the idea that dorsal PPC and the precuneus are involved in decision-related retrieval processes rather than successful remembering.

fMRI-guided TMS on cortical eye fields: the frontal but not intraparietal eye fields regulate the coupling between visuospatial attention and eye movements.

It is well known that parts of a visual scene are prioritized for visual processing, depending on the current situation. How the CNS moves this focus of attention across the visual image is largely unknown, although there is substantial evidence that preparation of an action is a key factor. Our results support the view that direct corticocortical feedback connections from frontal oculomotor areas to the visual cortex are responsible for the coupling between eye movements and shifts of visuospatial attention. Functional magnetic resonance imaging (fMRI)-guided transcranial magnetic stimulation (TMS) was applied to the frontal eye fields (FEFs) and intraparietal sulcus (IPS). A single pulse was delivered 60, 30, or 0 ms before a discrimination target was presented at, or next to, the target of a saccade in preparation. Results showed that the known enhancement of discrimination performance specific to locations to which eye movements are being prepared was enhanced by early TMS on the FEF contralateral to eye movement direction, whereas TMS on the IPS resulted in a general performance increase. The current findings indicate that the FEF affects selective visual processing within the visual cortex itself through direct feedback projections.

TMS pulses on the frontal eye fields break coupling between visuospatial attention and eye movements.

While preparing a saccadic eye movement, visual processing of the saccade goal is prioritized. Here, we provide evidence that the frontal eye fields (FEFs) are responsible for this coupling between eye movements and shifts of visuospatial attention. Functional magnetic resonance imaging (fMRI)-guided transcranial magnetic stimulation (TMS) was applied to the FEFs 30 ms before a discrimination target was presented at or next to the target of a saccade in preparation. Results showed that the well-known enhancement of discrimination performance on locations to which eye movements are being prepared was diminished by TMS contralateral to eye movement direction. Based on the present and other reports, we propose that saccade preparatory processes in the FEF affect selective visual processing within the visual cortex through feedback projections, in that way coupling saccade preparation and visuospatial attention.

Mutations in MVK, encoding mevalonate kinase, cause hyperimmunoglobulinaemia D and periodic fever syndrome.

Hyperimmunoglobulinaemia D and periodic fever syndrome (HIDS; MIM 260920) is an autosomal recessive disorder characterized by recurrent episodes of fever associated with lymphadenopathy, arthralgia, gastrointestinal dismay and skin rash. Diagnostic hallmark of HIDS is a constitutively elevated level of serum immunoglobulin D (IgD), although patients have been reported with normal IgD levels. To determine the underlying defect in HIDS, we analysed urine of several patients and discovered increased concentrations of mevalonic acid during severe episodes of fever, but not between crises. Subsequent analysis of cells from four unrelated HIDS patients revealed reduced activities of mevalonate kinase (MK; encoded by the gene MVK), a key enzyme of isoprenoid biosynthesis. Sequence analysis of MVK cDNA from the patients identified three different mutations, one of which was common to all patients. Expression of the mutant cDNAs in Escherichia coli showed that all three mutations affect the activity of the encoded proteins. Moreover, immunoblot analysis demonstrated a deficiency of MK protein in patient fibroblasts, indicating a protein-destabilizing effect of the mutations.

The success of dietary protein restriction in alkaptonuria patients is age-dependent.

Alkaptonuria is characterized by an increased urinary excretion of homogentisic acid, pigmentation of cartilage and connective tissues, and ultimately the development of inflammatory arthropathy. Various diets low in protein have been designed to decrease homogentisic acid excretion and to prevent the ochronotic pigmentation and arthritic lesions. However, limited information is available on the long-term beneficial effects of these diets. We reviewed the medical records of 16 patients aged 3-27 years (4 > 18 years) to ascertain the age of diagnosis, growth, development, social behaviour, signs of complications and longitudinal dietary compliance. The diagnosis of alkaptonuria was made at an average age of 1.4 years (2 months-4 years); following the diagnosis all patients were prescribed a diet with a protein content of 1.5 g/kg per day. All patients showed normal growth and development, and no major complications of the disease. Behavioural problems associated with poor dietary compliance emerged as the main problem. Dietary compliance decreased progressively with age. The effect of dietary protein restriction in homogentisic acid excretion was studied by fixing the amounts of protein in the diet at 1 g/kg per day and 3.5-5 g/kg per day during 8 days. Twelve patients, aged 4-27 years, participated in the investigation. Protein restriction resulted in a significantly lower excretion of homogentisic acid in the urine of children younger than 12 years (p < 0.01), whereas this effect was less obvious for adolescent and adult patients. The results suggest that restriction of protein intake may have a beneficial effect on alkaptonuric children; but continuation of this regimen to older age seems questionable and not practical.

Persistent low plasma vitamin E levels in premature infants surviving respiratory distress syndrome.

Plasma vitamin E levels were determined serially in preterm infants surviving respiratory distress syndrome (RDS) and in premature infants without RDS (control). Vitamin E intakes of the RDS and control infant group were not significantly different. The results of the study show that preterm infants surviving RDS have a persistent low plasma vitamin E level throughout the first 8 weeks of life. In contrast, in premature infants without RDS the plasma vitamin E level gradually increases to the adult level throughout the first 8 weeks of life. It is concluded that data on plasma vitamin E levels in premature infants with and without RDS should not be pooled together to obtain reference values. It is further suggested that premature infants with RDS might need more supplemental vitamin E than premature infants without RDS.

The cerebro-costo-mandibular syndrome: third report of familial occurrence.

Two male sibs with cerebro-costo-mandibular syndrome and spina bifida are described. The parents are physically and radiologically normal. A short review of the pertinent literature is given with special emphasis on the mode of inheritance.

The use of diclofenac sodium (Voltaren) suppositories as an antipyretic in children with fever due to acute infections: a double-blind, between-patient, placebo-controlled study.

In a placebo-controlled double-blind, between-patient trial the antipyretic effect of diclofenac sodium (voltaren) was studied in forty-three children ranging from 2-10 years of age. All patients were hospitalized because of acute illness associated with fever (38.5 degrees C-40.4 degrees C; mean 39.3 degrees C) due to viral or bacterial infections. The trial medication was given in the form of suppositories containing 25 mg of diclofenac sodium or as matching placebo to children aged from 2-5 years. The children aged from 6-10 years received a 50 mg diclofenac sodium suppository or placebo. Body temperature and pulse rate were measured at the time of administration and after 1/2, 1, 2, 4, and 6 hours. The results showed a return to normal temperature values after 2 hours in all patients receiving diclofenac sodium, whereas in the placebo group only minimal changes were observed. No unwanted effects were reported.

Application of enzymehistochemical methods to isolated subcellular fractions and to sucrose-ficoll density gradients. A contribution to the comparison of histochemical and biochemical data.

To compare histochemical and biochemical determinations of enzyme activities, enzymehistochemical procedures are applied to sections of pellets of subcelluar fractions. These investigations are of value to determine the subcellular localization of histochemically demonstrable enzyme activities and to test the homogeneity of an isolated fraction. In homogenating duckling liver a great part of the endothelial cells is not destructed and consequently is found in the nuclear fraction. Kupffer cell lysosomes land in the heavy mitochondrial fraction, whereas hepatocyte lysosomes are chiefly found in the light mitochondrial fraction. beta-Glucuronidase activity shows a preferentially microsomal localization. Application of enzymehistochemical staining reactions to discontinuous gradients and comparison with biochemical data provides additional information about the validity of an enzymehistochemical reaction. In rat liver the tetrazolium reductases show a distinctly dual localization: activity in the mitochondrial band and in microsomal bands. As to their localization in different bands of the gradients non-specific esterases demonstrate a clear pH-dependency.

Biochemical and ultrastructural aspects of the inhibited phagocytosis by neutrophil granulocytes in acute brain-damaged patients.

In a study of 60 head-injured patients inhibition of phagocytosis by neutrophil granulocytes was observed over a period of up to 5 weeks. This inhibition of phagocytosis could be correlated with the severity of head injury as well as with the state of unconsciousness at the time of the investigation. No correlation was found between neutrophil granulocyte counts and the inhibition of phagocytosis. A good correlation could be demonstrated between the level of lumbar CSF 5-HIAA and the inhibition of phagocytosis. After in vitro incubation with albumin the cells showed a recovery of phagocytosis. Electron micrographs of the cells showed ultrastructural appearances suggesting a changed permeability of the plasma membrane and, in addition, alterations in the cytoplasmic region beneath the plasma membrane. It is suggested that head injury may influence the pituitary-adrenal system and the autonomic nervous system, giving changes of neutrophil function and of neurotransmitter metabolism; these changes may represent an adaptation mechanism.