Faculty Bibliography

BACKGROUND AND PURPOSE/OBJECTIVE:Accurate localization of the ventral intermediate nucleus (VIM) within the dentatorubrothalamic tract (DRTT) is critical for effective neurosurgical treatment of essential tremor (ET). This study evaluated the feasibility and anatomical specificity of quantitative susceptibility mapping (QSM) for direct VIM/DRTT visualization, comparing it with conventional diffusion tractography-based reconstructions. MATERIALS AND METHODS/METHODS:Twenty-seven participants (10 healthy controls, 17 ET patients) were enrolled across two institutions and imaged on 3T MRI systems. QSM-defined VIM/DRTT regions were manually segmented based on characteristic hypointense susceptibility contrast. Whole-brain diffusion tractography was performed to reconstruct the DRTT, pyramidal tract (PT), and medial lemniscus (ML) tracts. Spatial overlap between QSM-and tractography-defined VIM/DRTT regions was calculated, as well as overlap with neighboring PT and ML tracts to assess specificity. RESULTS:Two participants were excluded due to insufficient VIM/DRTT streamlines in tractography reconstruction. In healthy controls, QSM-and tractography-defined VIM/DRTT showed high spatial correspondence (left: 87.6 ± 5.1%; right: 85.3 ± 6.5%). ET patients exhibited slightly lower overlap (mean range: 71.5 - 85.1%). Overlap with neighboring PT and ML tracts was minimal (<3.3%), confirming high anatomical specificity of QSM-derived VIM/DRTT regions. CONCLUSIONS:QSM enables direct visualization of the VIM/DRTT with high spatial agreement to conventional tractography-based approaches while demonstrating minimal overlap with adjacent tracts. These findings support QSM as a complementary or standalone imaging modality for improved, patient-specific neurosurgical targeting in ET. ABBREVIATIONS/BACKGROUND:DBS = deep brain stimulation; DRTT = dentatorubrothalamic tract; ET = essential tremor; ML = medial lemniscus; MRgFUS = MR-guided focused ultrasound; VIM = ventral intermediate nucleus; PT = pyramidal tract; QSM = quantitative susceptibility mapping; WM = white matter.

Alopecia is a medical condition that impact many people worldwide and has diverse causes, ranging from autoimmune to genetic factors. Hair transplantation represents a key therapeutic option for patients with progressive hair loss who are seeking improvement beyond the capacity of medications or less invasive procedures. While hair transplantation is most commonly utilized for androgenetic alopecia, individuals with other alopecia diagnoses may also benefit. The two main techniques for hair transplantation include follicular unit transplantation and follicular unit excision. Hair transplantation is particularly important given the profound psychosocial implications and cosmetic disfigurement associated with alopecia. Chronic hair loss patients may experience reduced self-esteem, increased depression and anxiety, and poorer quality of life. Despite the significance of hair transplantation, comprehensive guidelines informing the clinical and surgical management of transplant candidates remain limited. Therefore, this review aims to explore patient candidacy criteria, pretransplant medical therapy optimization, intraoperative considerations, and postoperative complications and medical management.

The prevalence of Alzheimer's disease and other dementias is increasing as populations live longer lifespans. Imaging is becoming a key component of the workup for patients with cognitive impairment or dementia. Integrated PET-MRI provides a unique opportunity for same-session multimodal characterization with many practical benefits to patients, referring physicians, radiologists, and researchers. The impact of integrated PET-MRI on clinical practice for early adopters of this technology can be profound. Classic imaging findings with integrated PET-MRI are illustrated for common neurodegenerative diseases or clinical-radiological syndromes. This review summarizes recent technical innovations that are being introduced into PET-MRI clinical practice and research for neurodegenerative disease. More recent MRI-based attenuation correction now performs similarly compared to PET-CT (e.g., whole-brain bias < 0.5%) such that early concerns for accurate PET tracer quantification with integrated PET-MRI appear resolved. Head motion is common in this patient population. MRI- and PET data-driven motion correction appear ready for routine use and should substantially improve PET-MRI image quality. PET-MRI by definition eliminates ~50% of the radiation from CT. Multiple hardware and software techniques for improving image quality with lower counts are reviewed (including motion correction). These methods can lower radiation to patients (and staff), increase scanner throughput, and generate better temporal resolution for dynamic PET. Deep learning has been broadly applied to PET-MRI. Deep learning analysis of PET and MRI data may provide accurate classification of different stages of Alzheimer's disease or predict progression to dementia. Over the past 5 years, clinical imaging of neurodegenerative disease has changed due to imaging research and the introduction of anti-amyloid immunotherapy-integrated PET-MRI is best suited for imaging these patients and its use appears poised for rapid growth outside academic medical centers. Evidence level: 5. Technical efficacy: Stage 3.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Gynecological cancers represent 10% to 15% of cancers in women, but brain metastases (BM) are uncommon, with limited evidence regarding their management. This study investigates the role of stereotactic radiosurgery (SRS) for BM from primary gynecological cancers. METHODS:Institutions of the International Radiosurgery Research Foundation participated in this study. Inclusion criteria required histological diagnosis of epithelial ovarian, cervical, or endometrial cancer, SRS between 2000 and 2020, and at least 1 imaging or clinical follow-up. RESULTS:A total of 276 patients having SRS for 977 BM were included. Median age at SRS was 62 years (IQR, 55-70). Primary cancer origin was ovarian in 128 (46%), cervical in 43 (16%), and endometrial in 105 patients (38%). Median Karnofsky Performance Scale was 80%, and systemic disease was active in 124 (45%) of patients. A median of 1 metastasis was treated (IQR, 1-3) per patient. Median individual metastasis volume was 0.27 cc (IQR, 0.05-1.59 cc). The majority (91%) received single-fraction SRS, using a median margin dose of 18 Gy (IQR, 16-20 Gy). Actuarial overall survival was 77%, 65%, and 44% at 6, 12, and 24 months, respectively. Predictors of worsened survival included older age, cervical and endometrial primary, previous whole-brain radiation therapy (WBRT), active systemic disease, worsened Karnofsky Performance Scale, absence of subsequent surgery, and increasing number of BM. Actuarial local control was 94% at 6 months, 89% at 12 months, and 78% at 24 months. Previous SRS or WBRT, tumor bed treatment, and cervical histology increased the risk of local failure. New remote BM and leptomeningeal dissemination occurred in 44% and 11% of patients, respectively. Adverse radiation effects (ARE) occurred in 13% of cases but were symptomatic in only 3%. Previous WBRT or SRS and increased tumor diameter increased the risk of ARE. CONCLUSION/CONCLUSIONS:SRS is an effective management for BM from gynecological cancers with low risks of symptomatic ARE.

BACKGROUND:Platelet-rich plasma (PRP) shows potential in treating androgenetic alopecia but lacks evidence for endocrine-induced alopecia (EIA) or persistent chemotherapy-induced alopecia (pCIA). OBJECTIVE:To evaluate safety and efficacy of PRP in breast cancer survivors with EIA or pCIA. METHODS:In this single-center, randomized, controlled trial, EIA and pCIA patients received PRP injections on one side of their scalp monthly for 3 months. Evaluations occurred at baseline and at week 12, followed by an optional cross-arm at week 24. The primary outcome was difference in global assessment scale (GAS) at week 12, assessed by a blinded investigator. Secondary outcomes included adverse events, hair-related quality of life, trichoscopic data, and circulating tumor cell (CTC) assay. RESULTS:Fifteen EIA and 12 pCIA patients enrolled. GAS improved from baseline to week 12 (+1.2 each, p < .001) but not statistically significant between treated and untreated sides (p > .05). Hair density increased for both sides (+21 and +16 hairs/cm2, respectively, p < .05), without difference between the sides (p > .05). Quality of life showed no improvement (41.1-39.4, p > .05). Adverse events included grade 1 to grade 3 scalp pain. Two of 12 CTC assays detected malignant cells in PRP, but no tumor seeding events were observed. CONCLUSION/CONCLUSIONS:PRP may increase hair density in EIA and pCIA patients and showed no adverse cancer outcomes or tumor seeding. Results may be confounded by possible PRP diffusion in split-scalp study design. CLINICALTRIALSGOV ID/BACKGROUND:NCT04459650.

OBJECTIVE:Childhood inhibited temperament (cIT) is associated with an increased risk for developing internalizing psychopathology. Neurobiological characteristics identified by structural magnetic resonance imaging (MRI) may elucidate the neural substrates for cIT, but studies are scarce and often focus on particular regions of interest. Moreover, current findings lack replication. This pre-registered analysis from the ENIGMA-Anxiety Working Group examined structural brain characteristics associated with cIT using a comprehensive whole-brain approach. METHOD/METHODS:Temperament assessments (behavioral observations, parental/teacher reports or self-reports on cIT before age 13) and MRI-data (age at scan: 6-25 years) from international research sites (Europe, North America, South America) were pooled for mega-analysis. Following image processing and quality control, associations between cIT and brain structure were examined in 3,803 participants. Subcortical volumes, cortical thickness and surface area (main analyses) and detailed subcortical characteristics (e.g. subnuclei, subfields, partial volume effects; exploratory analyses) were considered. RESULTS:= 0.029) in youth with parental/teacher reports on cIT-levels. Exploratory analyses revealed findings in hippocampus, putamen and caudate, but most did not survive statistical correction for multiple testing. CONCLUSION/CONCLUSIONS:This mega-analysis found no consistent associations between cIT and regional brain structure, although the role of parietal regions warrants further investigation. Future studies should consider brain function in cIT, preferably using longitudinal designs.

Precision-targeted ultrasonic neuromodulation offers immense potential for studying brain function and treating neurological diseases. Yet, its application has been limited by challenges in achieving precise spatio-temporal control and monitoring of ultrasound effects on brain circuits. Here we show that transcranial ultrasound elicits direct and highly focal responses, which can be dynamically steered at spatio-temporal scales relevant for neural function. Furthermore, holographic transcranial ultrasound stimulation allows direct control of the stimulated volume and actively modulates local and mid-range network projections, effectively lowering the activation threshold by an order of magnitude. To better understand this previously unexplored excitability regime not fully explained by the conventional pressure-frequency dyad, we developed a dual modelling framework, where both an empirical and a mechanistic model were constructed to capture the intricacies of holographic transcranial ultrasound stimulation. These models achieve qualitative agreement with our experimental results, suggesting that these findings are predominantly driven by putative network interactions. Our results bring insight on the complex interaction mechanisms of ultrasound with neural tissue and highlight its potential for the noninvasive interfacing of distributed brain networks.

BACKGROUND AND AIMS/OBJECTIVE:receptor modulator for the treatment of moderately to severely active ulcerative colitis (UC). In this post hoc analysis, induction and maintenance efficacy of etrasimod 2 mg vs placebo were assessed by baseline Mayo endoscopic subscore (ES) in ELEVATE UC 52 and ELEVATE UC 12. METHODS:Moderate and severe endoscopic disease were defined as a centrally-read ES of 2 and 3, respectively. Efficacy endpoints were evaluated at Weeks 12 (pooled population) and 52 (ELEVATE UC 52). Subgroup analyses were stratified by baseline modified Mayo score (4-6 vs 7-9) and prior biologic/Janus kinase inhibitor exposure. RESULTS:Overall, 235 patients with moderate and 292 with severe endoscopic disease received etrasimod; 112 and 148 patients, respectively, received placebo. At both time points, significantly greater proportions of patients receiving etrasimod compared with placebo achieved clinical remission in the moderate (Week 12: 38.3% vs 17.9%; Week 52: 36.5% vs 14.3%; both P < .001) and severe (Week 12: 18.2% vs 6.1%; Week 52: 29.4% vs 3.4%; both P < .001) endoscopic disease subgroups. Similar efficacy was observed at Weeks 12 and 52 for most endpoints. The proportion of etrasimod-treated patients with severe endoscopic disease achieving endpoints was generally numerically higher at Week 52 vs Week 12, relative to placebo. Subgroup analysis findings were generally similar. CONCLUSIONS:Etrasimod demonstrated significant induction and maintenance efficacy over placebo in both moderate and severe endoscopic disease. Response to etrasimod in patients with severe endoscopic disease may continue to improve beyond 12-week induction therapy (ClinicalTrials.gov: NCT03945188; NCT03996369).

OBJECTIVES/OBJECTIVE:Post-colonoscopy colorectal cancer (PCCRC) represents an important real-world colonoscopy quality indicator. Using a national database, we evaluated predictors of PCCRC in fecal immunochemical test (FIT)-positive individuals, determined the PCCRC 3-year rate (PCCRC-3y), and performed a root cause analysis (RCA). METHODS:This retrospective cohort study evaluated FIT-positive patients who underwent colonoscopy from January 2015 to July 2022. Data was collected from the Veterans Affairs (VA) national database. PCCRC was defined as CRC detected ≥6 months after colonoscopy. CRC was identified using SNOMED codes and the VA Cancer Registry. The World Endoscopy Organization methodology was used to perform the RCA and calculate the PCCRC-3y rate. RESULTS:We identified 132 PCCRCs among 52,167 FIT-positive individuals. The PCCRC-3y rate was 6.4% (95% CI, 5.0-7.7%). PCCRC locations were proximal colon (43.2%), distal colon (34.8%), and rectum (22%). Root causes were likely new CRC (17.4%), missed lesions with adequate (31.2%) or inadequate (9.8%) examination, incomplete polyp resection (22%), and detected but unresected lesions (19.7%). 16.7% of patients with PCCRC had poor bowel preparation on index colonoscopy. The cecal intubation rate was 88.6% and rectal retroflexion rate was 84.5%. In 14.4% of cases, recommended surveillance intervals did not adhere to established guidelines. Independent predictors of PCCRC were ages 70-79 (HR 7.86; 95% CI, 1.08-57.39), age ≥80 (HR 10.18; 95% CI, 1.06-97.98), tubulovillous adenoma (HR 3.98; 95% CI, 2.52-6.29), and adenoma with high-grade dysplasia (HR 10.15; 95% CI, 5.91-17.42). CONCLUSIONS:Among FIT-positive individuals, the PCCRC-3y rate was 6.4%, with missed lesions and incomplete resection as key contributors. These findings provide useful information on quality metrics in FIT-based CRC screening programs.