Minimum resolution requirements of digital pathology images for accurate classification

Digitization of pathology has been proposed as an essential mitigation strategy for the severe staffing crisis facing most pathology departments. Despite its benefits, several barriers have prevented widespread adoption of digital workflows, including cost and pathologist reluctance due to subjective image quality concerns. In this work, we quantitatively determine the minimum image quality requirements for binary classification of histopathology images of breast tissue in terms of spatial and sampling resolution. We train an ensemble of deep learning classifier models on publicly available datasets to obtain a baseline accuracy and computationally degrade these images according to our derived theoretical model to identify the minimum resolution necessary for acceptable diagnostic accuracy. Our results show that images can be degraded significantly below the resolution of most commercial whole-slide imaging systems while maintaining reasonable accuracy, demonstrating that macroscopic features are sufficient for binary classification of stained breast tissue. A rapid low-cost imaging system capable of identifying healthy tissue not requiring human assessment could serve as a triage system for reducing caseloads and alleviating the significant strain on the current workforce.

The effect of baseline cognition and delirium on long-term cognitive impairment and mortality: a prospective population-based study

Background

There is an unmet public health need to understand better the relationship between baseline cognitive function, the occurrence and severity of delirium, and subsequent cognitive decline. Our aim was to quantify the relationship between baseline cognition and delirium and follow-up cognitive impairment.

Methods

We did a prospective longitudinal study in a stable representative community sample of adults aged 70 years or older who were registered with a Camden-based general practitioner in the London Borough of Camden (London, UK). Participants were recruited by invitation letters from general practice lists or by direct recruitment of patients from memory clinics or patients recently discharged from secondary care. We quantified baseline cognitive function with the modified Telephone Interview for Cognitive Status. In patients who were admitted to hospital, we undertook daily assessments of delirium using the Memorial Delirium Assessment Scale (MDAS). We estimated the association of pre-admission baseline cognitive function with delirium prevalence, severity, and duration. We assessed subsequent cognitive function 2 years after baseline recruitment using the Telephone Interview for Cognitive Status. Regression models were adjusted by age, sex, education, illness severity, and frailty.

Findings

We recruited 1510 participants (median age 77 [IQR 73-82], 57% women) between March, 2017, and October, 2018. 209 participants were admitted to hospital across 371 episodes (1999 person-days of assessment). Better baseline cognition was associated with a lower risk of delirium (odds ratio 0·63, 95% CI 0·45 to 0·89) and with less severe delirium (-1·6 MDAS point, 95% CI -2·6 to -0·7). Individuals with high baseline cognition (baseline Z score +2·0 SD) had demonstrable decline even without delirium (follow-up Z score +1·2 SD). However, those with a high delirium burden had an even larger absolute decline of 2·2 SD in Z score (follow-up Z score -0·2). Once individuals had more than 2 days of moderate delirium, the rates of death over 2 years were similar regardless of baseline cognition; a better baseline cognition no longer conferred any mortality benefit.

Interpretation

A higher baseline cognitive function is associated with a good prognosis with regard to likelihood and severity of delirium. However, those with a high baseline cognition and with delirium had the highest degree of cognitive decline, a change similar to the decline observed in individuals with a high amyloid burden in other cohorts. Older people with a healthy baseline cognitive function who develop delirium stand to lose the most after delirium. This group could benefit from targeted cognitive rehabilitation interventions after delirium.

Fast catheter segmentation from echocardiographic sequences based on segmentation from corresponding X-ray fluoroscopy for cardiac catheterization interventions

Echocardiography is a potential alternative to X-ray fluoroscopy in cardiac catheterization given its richness in soft tissue information and its lack of ionizing radiation. However, its small field of view and acoustic artifacts make direct automatic segmentation of the catheters very challenging. In this study, a fast catheter segmentation framework for echocardiographic imaging guided by the segmentation of corresponding X-ray fluoroscopic imaging is proposed. The complete framework consists of: 1) catheter initialization in the first X-ray frame; 2) catheter tracking in the rest of the X-ray sequence; 3) fast registration of corresponding X-ray and ultrasound frames; and 4) catheter segmentation in ultrasound images guided by the results of both X-ray tracking and fast registration. The main contributions include: 1) a Kalman filter-based growing strategy with more clinical data evalution; 2) a SURF detector applied in a constrained search space for catheter segmentation in ultrasound images; 3) a two layer hierarchical graph model to integrate and smooth catheter fragments into a complete catheter; and 4) the integration of these components into a system for clinical applications. This framework is evaluated on five sequences of porcine data and four sequences of patient data comprising more than 3000 X-ray frames and more than 1000 ultrasound frames. The results show that our algorithm is able to track the catheter in ultrasound images at 1.3 s per frame, with an error of less than 2 mm. However, although this may satisfy the accuracy for visualization purposes and is also fast, the algorithm still needs to be further accelerated for real-time clinical applications.

Maintaining health by balancing microbial exposure and prevention of infection: the hygiene hypothesis versus the hypothesis of early immune challenge

The human immune system is inseparably bonded to an individual's personal micro-biome from birth to death. Since the beginning of life, commensal relationships have ensured the survival of micro- and macro-organisms within complex relationships. However, technological advances and altered lifestyle imposed new rules for this interaction during recent decades. It has been observed that reduced exposure to micro-organisms and parasites results in decreased morbidity and mortality, but is also associated with a rising prevalence of atopic disorders and autoimmune diseases, mostly in industrialized countries. This inverse relationship is described by the 'hygiene hypothesis', put forward in 1989, yet this term only imperfectly describes these observations, as excessive hygiene or hygienic measures may not directly be the central cause. The lack of appropriate immune stimulation during early childhood with the consequence of disturbed alignment in the sequence of encountering self- or non-self-antigens might account in the rise of atopy and autoimmune disease. For this reason we propose the term 'early immune challenge hypothesis'. This concept highlights the importance of immune priming in early life in the context of genetic, social, geographic, cultural, and economic background. Moreover, it emphasizes the central role of 'training' of regulatory T-cells through sufficient microbial exposure, leading to a robust, healthy balance between inflammation and anti-inflammation or immune tolerance. Insufficient exposure might result in abnormal immune regulatory development. Finally, it incorporates the idea of encountering 'old friends' - organisms that shaped our immune system during human phylogeny. This article gives a comprehensive overview of the relationship between microbial exposure, and the incidence of asthma and hay fever is outlined. Although the outcomes of these studies originally were interpreted in the framework of the hygiene hypothesis, they may suit the concept of the hypothesis of early immune challenge even better. Moreover, recent studies have revealed that TH or TReg imbalances in disease may be partially corrected by the administration of helminthic or bacterial extracts.

Clostridium difficile: emergence of hypervirulence and fluoroquinolone resistance

Clostridium difficile is a well-known cause of sporadic and healthcare-associated diarrhea. Multihospital outbreaks due to a single strain and outbreaks associated with antibiotic selective pressure, especially clindamycin, have been well documented. Severe cases and fatalities from C. difficile are uncommon. The recent global emergence of a hypervirulent strain containing binary toxin (Toxinotype III ribotype 027), with or without deletion in a regulatory gene (tcdC gene), together with high-level resistance to third generation fluoroquinolones, has been associated with increased morbidity and mortality. Although the defective regulatory gene locus is associated with increased toxin production in vitro, the in vivo significance of this mutation and of the binary toxin remains undefined. To date, treatment strategies have not evolved in response to the emergence of this hypervirulaent strain. We provide a critical, quantitative summary of the evolving clinical and molecular epidemiology of C. difficile along with implications relevant to future treatment strategies.

Failure of trimethoprim/sulfamethoxazole prophylaxis for Pneumocystis carinii pneumonia with concurrent leucovorin use

Pneumocystis carinii is a common cause of pneumonia in patients with AIDS, however, the incidence has dropped with the availability of effective prophylactic regimens. First-line treatment for both acute Pneumocystis pneumonia and chronic prophylaxis is trimethoprim/sulfamethoxazole (TMP/SMX). This combination can cause hypersensitivity reactions as well as myelosuppression. The simultaneous administration of leucovorin during acute treatment has been shown to reduce the incidence of neutropenia, but may interfere with the efficacy of TMP/SMX. We report a case of P. carinii pneumonia in a patient with AIDS who failed TMP/SMX prophylaxis while taking leucovorin.

Disseminated Nocardia asteroides presenting as pulmonary non-caseating granulomas in a patient with Waldenstrom macroglobulinemia

Disseminated nocardiosis has never been described before in a patient with Waldenstrom macroglobulinemia. We report an unusual case of disseminated nocardiosis in a patient with Waldenstrom macroglobulinemia who presented with pulmonary non-caseating granulomas. The patient was successfully treated with trimethoprim-sulfamethoxazole (TMP-SMX) for 1 year.

Herpes simplex encephalitis--an atypical case

Herpes simplex virus (HSV) is a common cause of viral encephalitis. Herpes simplex encephalitis (HSE) typically presents with acute neurologic changes and the initial cerebrospinal fluid examination is nearly always abnormal. We report a case of a patient with HSE and normal initial CSF analysis. This resulted in delayed diagnosis and therapy with subsequent severe neurolgical sequelae. Herpes simplex infection should be included in the differential diagnosis of encephalopathic patients and a normal CSF examination.

Cutaneous infection due to Mycobacterium kansasii

A patient presented with chronic leg ulcers after a mowing accident. He received several courses of antibiotics for presumed cellulitis, underwent surgical debridement, and was treated empirically with cyclosporin for presumed pyoderma gangrenosum, all without improvement. Cultures from prior debridement revealed Mycobacterium kansasii, and he was successfully treated with triple antituberculous regimen. Cutaneous infections due to this slow growing Mycobacterium are rare and may resemble cellulitis or sporotrichosis. Mycobacterium kansasii should be included in the differential diagnosis of skin infections with an indolent course and lack of response to antibiotics.

Hemiplegic migraine induced by exertion

BACKGROUND

It is known that exertion can aggravate migraine headache. However, the relationship between exertion and migraine aura is unknown.

OBJECTIVE

To study the relationship between exertion and migraine aura.

DESIGN

Case report.

SETTING

Tertiary care hospital.

PATIENT

A 67-year-old man presented with recurrent attacks of exertion-induced hemiplegic migraine. Since the hemiparetic attacks were exertion induced, they were initially ascribed to recurrent transient ischemic attacks. However, the clinical picture, normal findings on cerebral angiography and neuroimaging (during the period of hemiparesis), lack of response to treatment with antiplatelets and anticoagulants, and successful treatment with verapamil suggested that the hemiparesis was not due to ischemia, but was indeed a migraine aura. We suggest that exertion induced the aura of hemiparesis by lowering the threshold for the development of cortical spreading depression. Even though our patient had no family history of hemiplegic migraine, a mutation in an ion channel gene (eg, the CACNA1A gene on chromosome 19) might account for his episodic attacks.

CONCLUSION

Migraine aura should be included in the differential diagnosis of exertion-induced focal neurologic deficit.

Chondritis attributable to Lactobacillus after ear piercing

A diabetic patient was admitted with ear pain and purulent discharge after "high ear piercing" by a friend. After investigation she was found to have chondritis, complicated by an abscess. Wound cultures grew Lactobacillus species. Patient responded to parenteral antibiotics without suffering cosmetic deformity. Sterile technique, adherence to post-piercing ear hygiene, and avoiding piercing the auricular cartilage may prevent complications associated with ear piercing. Lactobacillus should be included in the differential of pathogens involved in post-piercing chondritis.

CNS pseudovasculitis in a patient with pheochromocytoma

The authors report a patient with angiographic findings resembling CNS vasculitis (CNS pseudovasculitis) who was found to have a pheochromocytoma. The angiographic changes resolved after surgical resection of the pheochromocytoma. Pheochromocytoma should be included in the differential diagnosis of angiographic findings suggestive of CNS vasculitis.