Artificial intelligence for detection of intracranial haemorrhage on head computed tomography scans: diagnostic accuracy in Hong Kong

INTRODUCTION

The use of artificial intelligence (AI) to identify acute intracranial haemorrhage (ICH) on computed tomography (CT) scans may facilitate initial imaging interpretation in the accident and emergency department. However, AI model construction requires a large amount of annotated data for training, and validation with real-world data has been limited. We developed an algorithm using an open-access dataset of CT slices, then assessed its utility in clinical practice by validating its performance on CT scans from our institution.

METHODS

Using a publicly available international dataset of >750 000 expert-labelled CT slices, we developed an AI model which determines ICH probability for each CT scan and nominates five potential ICH-positive CT slices for review. We validated the model using retrospective data from 1372 non-contrast head CT scans (84 [6.1%] with ICH) collected at our institution.

RESULTS

The model achieved an area under the curve of 0.842 (95% confidence interval=0.791-0.894; P<0.001) for scan-based detection of ICH. A pre-specified probability threshold of ≥50% for the presence of ICH yielded 78.6% accuracy, 73% sensitivity, 79% specificity, 18.6% positive predictive value, and 97.8% negative predictive value. There were 62 true-positive scans and 22 false-negative scans, which could be reduced to six false-negative scans by manual review of model-nominated CT slices.

CONCLUSION

Our model exhibited good accuracy in the CT scan-based detection of ICH, considering the low prevalence of ICH in Hong Kong. Model refinement to allow direct localisation of ICH will facilitate the use of AI solutions in clinical practice.

Pattern of recurrence and factors associated with cerebrospinal fluid dissemination of glioblastoma in Chinese patients

Background:

Pattern of recurrence of glioblastoma (GBM) seems to have undergone some shifts from distant metastasis as a rarity to a higher proportion, including disease disseminated via cerebrospinal fluid (CSF) pathway. There is still no report on the pattern of recurrence for Chinese population. Here, we evaluated the pattern of recurrence of GBM in Chinese patients along with factors that could affect the distribution of recurrence.

Methods:

Medical records of GBM patients with definite recurrence were reviewed. Local recurrence was defined as tumor regrowth within the preoperative abnormal signals on magnetic resonance imaging (MRI) T2 sequence. New recurrence was a new lesion away from the preoperative T2 abnormalities. New recurrence in contact with CSF pathways was registered as new CSF dissemination. Progress-free survival (PFS) and survival after progress were compared using the Kaplan–Meier survival curves. Potential risk factors for new CSF dissemination were assessed using univariate models followed by multivariate analysis.

Results:

Thirty-six patients were proven to have recurrence; 22 local and 14 new recurrences. Among the 14 patients, 11 had new CSF dissemination. Median PFS for local, new parenchymal recurrence, and new CSF dissemination were 5.5 months, 9.9 months, and 12.1 months, whereas survival after progress were 6.1 months, 5.7 months, and 16.9 months, respectively. The ventricular entry during surgery and the completion of concomitant chemoradiotherapy were risk factors for new CSF dissemination. O⁶-methylguanine-DNA methyltransferase methylation was associated with the development of CSF dissemination.

Conclusion:

The majority of recurrence remained local (22/36, 61%). However, CSF dissemination was up to 30% (11/36). PFS for patients with CSF dissemination was the longest, and paradoxically survival after progress was the shortest. Ventricular entry should be avoided. Whole craniospinal MRI surveillance should be included for these patients.

Screening for intracranial aneurysms? Prevalence of unruptured intracranial aneurysms in Hong Kong Chinese

OBJECT The objective of this study was to generate data on the local prevalence of unruptured intracranial aneurysms (UIAs) in asymptomatic Hong Kong Chinese individuals. First-degree relatives of patients with aneurysmal subarachnoid hemorrhage (aSAH) were recruited as surrogates of the general population and to explore the potential role of screening in this locality. METHODS The authors identified first-degree relatives of consecutive patients with subarachnoid hemorrhage from a ruptured aneurysm who were admitted to a university hospital in Hong Kong from June 2008 to December 2010. Magnetic resonance angiography (MRA) was the imaging modality used to screen the cerebral vasculature of these asymptomatic individuals. If MRA showed abnormal findings, CT angiography was performed to confirm the MRA findings. RESULTS In total, 7 UIAs were identified from the 305 MR angiograms obtained. The prevalence of UIAs in first-degree relatives of patients with aSAH in the Hong Kong Chinese population was 2.30% (95% CI1.02%-4.76%). This percentage was lower than the prevalence rate of 3.2% from a meta-analysis of the literature. The sizes of the UIAs detected ranged from 1.4 mm to 7.5 mm; 85.7% of the UIAs detected in this study were < 5 mm, in contrast to 66% noted in the literature. One of the UIAs identified underwent endovascular stent placement with a flow diverter. None of the UIAs identified ruptured or became symptomatic during a median follow-up period of 3.5 years. CONCLUSIONS The prevalence of UIAs in first-degree relatives of patients with aSAH in the Hong Kong Chinese population was lower than that in Caucasians. At the same time, most of the UIAs detected in this study were small (85.7% were < 5 mm, vs 66% in a meta-analysis). With a similar incidence of aSAH in Hong Kong (7.5 per 100,000 person-years) as compared with data cited in the literature, the hypothesis that UIA rupture risk size threshold is different in Chinese patients should be further investigated.

Spontaneous intracranial hypotension: improving recognition and treatment strategies in the local setting

We report a case of spontaneous intracranial hypotension with classic symptoms of orthostatic headache and acute presentation of subdural haematoma on computed tomographic scan. Conventional approach with conservative treatment was initially adopted. The patient's condition, however, deteriorated after 2 weeks, requiring surgical evacuation of the intracranial haemorrhage. We reviewed the clinical features of this disease and the correlated magnetic resonance imaging findings with the pathophysiological mechanisms, and described treatment strategies in the local setting. Subtle findings on initial computed tomographic scan are also reported which might improve pathology recognition. Spontaneous intracranial hypotension is not uncommonly encountered in Hong Kong, and physicians must adopt a high level of clinical suspicion to facilitate early diagnosis and appropriate management. In addition, novel therapeutic approaches may be required in those with recurrent symptoms or who are refractory to current treatment strategies.

A sequential comparison on the risk of haemorrhage with different sizes of biopsy needles for stereotactic brain biopsy

AIM

To compare the risk of postoperative haemorrhage with different sizes of brain biopsy needles.

PATIENTS AND METHOD

A cohort of patients using a 2.5-mm outer diameter side-cutting biopsy needle was compared to a subsequent cohort using a 1.8-mm needle of the same type. All data were collected prospectively. A CT scan was done within 12 h after surgery. Any visible haemorrhage at the operated site was documented.

RESULTS

From 2007 to 2013, 54 stereotactic brain biopsies (all frameless except for one frame-based) were performed. The 2.5-mm group comprised 29 procedures from 2007 to 2009. The 1.8-mm group comprised the subsequent 25 procedures. The diagnostic yields were 90 and 96% in the 2.5- and the 1.8-mm group, respectively (p = 0.615). Comparing the 2.5- and the 1.8-mm group, haemorrhage was significantly reduced: incidence (72 vs. 40%, p = 0.016); size of haemorrhage (mean 7.2 vs. 2.6 mm, p = 0.002); proportion of haemorrhage size >10 mm (34.5 vs. 4%, p = 0.006). Symptomatic haemorrhage rates were 3.4 and 0.0% in the 2.5- and the 1.8-mm group, respectively (p = 1.00).

CONCLUSION

The 1.8-mm outer diameter needle carried a lower risk of postoperative haemorrhage than the 2.5-mm one, without compromising the diagnostic yield.

Intracranial electroencephalogram to evaluate refractory temporal and frontal lobe epilepsy

OBJECTIVE

We undertook a collaborative study in a multidisciplinary team to channel refractory epilepsy patients to test a hypothesis about placement of intracranial electroencephalography arrays.

DESIGN

This was a descriptive case series. Prospective non-invasive presurgical evaluations were based on clinical semiology, magnetic resonance imaging, video-electroencephalography findings and neuropsychological assessments. If the results were discordant, a hypothesis was generated using individualised combinations of positron emission tomography, single-photon emission computed tomography, functional magnetic resonance imaging and Wada tests. The indications for intracranial electroencephalography were: (a) focal magnetic resonance imaging, ictal/interictal scalp electroencephalography with variable results (group A); (b) multi-focal magnetic resonance imaging, focal/multi-focal ictal scalp electroencephalography (group B); (c) non-lesional magnetic resonance imaging, focal/multi-focal ictal scalp electroencephalography (group C). We evaluated whether the seizure-onset zones and eloquent areas were delineated, surgical outcomes (if operated on), and pathology results.

SETTING

A tertiary referral centre for neurology in Hong Kong.

PATIENTS

A total of 105 refractory epilepsy patients completed non-invasive presurgical evaluations over the period 2007 to 2009. Thirty-two patients were eligible for direct resective surgery, and another 25 patients had a testing hypothesis formulated. Of these 25 patients, 10 were eligible for intracranial electroencephalography based on technical/financial considerations.

RESULTS

All 10 patients (group A=2, group B=4, group C=4) had their epileptogenic zones defined. Six patients underwent functional mapping, all of whom had their eloquent areas defined. Seven of the 10 patients underwent resective surgery; four of them achieved Engel class I/II outcomes. The dichotomised outcomes were 100% (group A), 50% (group B), and 33% (group C) achieving Engel class I/II. Two patients had asymptomatic subdural haematoma. There was no intracranial infection or operative mortality. In five (71%) of seven of the patients, a histological diagnosis was established.

CONCLUSION

Proper deployment of intracranial electroencephalography is useful in the presurgical evaluation of patients with refractory epilepsy. This modality of management is potentially of benefit for patients with refractory epilepsy, but is underutilised locally.

Disseminated amyloidosis presenting with right proximal femur pathological fracture in a haemodialysis end-stage renal failure patient

Osteoarticular amyloidosis can be one of the musculoskeletal system manifestations related to dialysis. We share our experience in dealing with a case of disseminated haemodialysis-associated amyloidosis in a 74-year-old end-stage renal failure patient. This patient suffered from a serious complication, namely an unprovoked pathological fracture at the basal neck region of the right femur. Polyarticular cystic and lytic lesions over the contralateral proximal femur, bilateral proximal humerus and the right lunate were noted on further imaging. In view of extensive amyloidotic infiltration into the proximal femur as well as the acetabulum, a cemented total hip arthroplasty operation was performed for pain relief and restoration of function. The radiological investigations, diagnostic challenges, operative as well as histopathological findings are discussed. This disease should be considered in the differential diagnosis of pathological juxta-articular fracture in patients undergoing haemodialysis.

An uncommon cause of recurrent falls in an elderly man

Falls are common among the elderly population. Examinations for the cause of falls are usually mundane, but may be challenging, leading to surprising diagnoses. We report on a previously healthy elderly man who presented with repeated falls and rapidly progressive limitations in mobility, in addition to a stutter. Neuroimaging was particularly helpful for making the diagnosis in this patient.