Prevalence and Predictors of Hemorrhagic Foci on Long-term Follow-up MRI of Recent Single Subcortical Infarcts.

Hemorrhagic foci surrounding the lacune in the long-term evolution of recent single subcortical infarcts (RSSIs) remains largely unexplored. We aimed to determine the prevalence, characteristics, and predictors of hemorrhagic foci in patients with RSSI. From a prospective, longitudinal study of RSSIs, we recruited patients who underwent multimodal MRI assessments both at baseline and approximately one year after the stroke onset. Hemorrhagic foci were identified using susceptibility-weighted imaging (SWI). Among 101 patients with RSSI, nearly half (n = 45, 44.6%) had hemorrhagic foci within the index RSSI lesions on follow-up SWI. RSSIs with hemorrhagic foci formation were associated with a longer time to follow-up imaging (median 449 versus 401 days, P = 0.005) and higher likelihood of being located in the anterior circulation compared to those without hemorrhagic foci (88.9% versus 64.3%, P = 0.003). Hemorrhagic foci were also associated with larger lesion size (P < 0.001), a higher proportion of cavitation formation (P = 0.003), higher baseline NIHSS scores (P = 0.004), and poorer functional outcomes (P = 0.001). In the subset of RSSIs in the lenticulostriate artery (LSA) territory, after adjustment for covariates, larger initial lesion volume (OR 1.80, 95% CI 1.13-2.87; P = 0.014) and greater decreases in LSA total length (OR 0.59, 95% CI 0.36-0.96; P = 0.035) were independently associated with hemorrhagic foci formation. The extent of ischemia in the initial infarct is predictive of the presence of hemorrhagic residues. Our findings contribute to the current understanding of the mechanisms underlying the evolution of RSSIs.

Association of compromised cerebral perfusion with lenticulostriate artery impairments in the subacute phase of branch atheromatous disease.

Background Purpose: Whether altered cerebral perfusion is associated with the pathogenesis of single subcortical infarctions (SSIs) in the lenticulostriate artery (LSA) territory remains unclear. Objective: We aimed to assess whether cerebral perfusion abnormalities are related to LSA impairments in the subacute phase of SSIs and then to examine their correlations with etiological subtypes of SSIs. Methods: A total of 110 patients with acute SSIs in the LSA territory were prospectively recruited between July 2017 and October 2021, and they underwent magnetic resonance perfusion-weighted imaging (PWI) and whole-brain vessel-wall imaging (VWI) within 7 days of stroke onset. Based on VWI, patients were assigned to one of two SSI subtypes: branch atheromatous disease (BAD, n = 78, 70.9%) or lacunar infarction related to cerebral small vessel disease (CSVD-related LI, n = 32, 29.1%). Perfusion maps and LSA morphology were also quantitatively assessed. Results: Based on PWI, 22 patients (20%) had hypoperfusion and 88 (80%) showed normal perfusion. Compared with normal individuals, patients with hypoperfusion showed shorter average LSA length (23.48 ± 4.81 mm versus 25.47 ± 3.74 mm, p = 0.037). Compared with patients with CSVD-related LI, patients with BAD had significantly lower relative cerebral blood flow [0.95 (IQR 0.81-1.12) versus 1.04 (IQR 0.92-1.22); p = 0.036] and cerebral blood volume [0.95 (IQR 0.84-1.15) versus 1.14 (IQR 0.97-1.27); p = 0.020] after adjusting for hypertension, number of LSA branches, and infarct volume. Conclusion: Compromised cerebral perfusion is associated with impairments in the LSA and with BAD pathogenesis. Perfusion magnetic resonance imaging can provide important insights into acute SSI pathophysiology, and it may be useful for determining the clinical significance of perfusion abnormalities in BAD occurrence.

Fully 3D list-mode time-of-flight PET image reconstruction on GPUs using CUDA.

PURPOSE: List-mode processing is an efficient way of dealing with the sparse nature of positron emission tomography (PET) data sets and is the processing method of choice for time-of-flight (ToF) PET image reconstruction. However, the massive amount of computation involved in forward projection and backprojection limits the application of list-mode reconstruction in practice, and makes it challenging to incorporate accurate system modeling. METHODS: The authors present a novel formulation for computing line projection operations on graphics processing units (GPUs) using the compute unified device architecture (CUDA) framework, and apply the formulation to list-mode ordered-subsets expectation maximization (OSEM) image reconstruction. Our method overcomes well-known GPU challenges such as divergence of compute threads, limited bandwidth of global memory, and limited size of shared memory, while exploiting GPU capabilities such as fast access to shared memory and efficient linear interpolation of texture memory. Execution time comparison and image quality analysis of the GPU-CUDA method and the central processing unit (CPU) method are performed on several data sets acquired on a preclinical scanner and a clinical ToF scanner. RESULTS: When applied to line projection operations for non-ToF list-mode PET, this new GPU-CUDA method is >200 times faster than a single-threaded reference CPU implementation. For ToF reconstruction, we exploit a ToF-specific optimization to improve the efficiency of our parallel processing method, resulting in GPU reconstruction >300 times faster than the CPU counterpart. For a typical whole-body scan with 75 × 75 × 26 image matrix, 40.7 million LORs, 33 subsets, and 3 iterations, the overall processing time is 7.7 s for GPU and 42 min for a single-threaded CPU. Image quality and accuracy are preserved for multiple imaging configurations and reconstruction parameters, with normalized root mean squared (RMS) deviation less than 1% between CPU and GPU-generated images for all cases. CONCLUSIONS: A list-mode ToF OSEM library was developed on the GPU-CUDA platform. Our studies show that the GPU reformulation is considerably faster than a single-threaded reference CPU method especially for ToF processing, while producing virtually identical images. This new method can be easily adapted to enable more advanced algorithms for high resolution PET reconstruction based on additional information such as depth of interaction (DoI), photon energy, and point spread functions (PSFs).

Microsurgical treatment of cerebrospinal fluid rhinorrhea in sphenoidal sinus.

OBJECTIVE: To explore the clinical manifestation, diagnosis and surgical treatment of cerebrospinal fluid rhinorrhea in sphenoidal sinus. METHODS: Nine cases of cerebrospinal fluid rhinorrhea in sphenoidal sinus from 2007 to 2009 were retrospectively analyzed consisting of their possible etiological factors, clinical manifestations, localization of the leakage site and treatment methods. Among them, there were 3 cases of traumatic rhinorrhea, 4 postoperative rhinorrhea and 2 spontaneous rhinorrhea. All 9 patients underwent 3-dimensional CT scan in sellar region including all para-nasal sinus. Leakage site was identified and repairing procedure was performed through trans-sphenoidal approach. RESULTS: All cases were cured with the trans-sphenoidal microsurgical procedure. They were followed up for 9 months to 2 years. No recurrence, no infection and epilepsy complications were observed. CONCLUSION: For the cerebrospinal fluid rhinorrhea at sphenoidal sinus, it is critical to identify the leakage site accurately and the trans-sphenoidal approach is a microinvasive and effective way to repair the leakage, which is worthy to be advocated.