Temporary radiation-induced alopecia after embolization of a cerebral arteriovenous malformation

Anagen Effluvium after Neurointerventional Radiation: Trichoscopy as a Diagnostic Ally

Minimally invasive procedures for vascular brain lesions are being performed more frequently. Radiation exposure caused by endovascular embolization of cerebral aneurysms may give rise to nonscarring scalp alopecia located in the treated area. Clinical and trichoscopic features of this type of alopecia are similar to alopecia areata (AA). Herein, we performed a comprehensive review to describe the clinical and trichoscopic characteristics of radiation-induced anagen effluvium. Predominant trichoscopic findings include black dots, yellow dots, short vellus hairs, and absence of exclamation marks hairs. It is important to consider this diagnosis in patients who have recently undergone such procedures that can easily be misdiagnosed as AA.

Dosimetric Predictors of Acute and Chronic Alopecia in Primary Brain Cancer Patients Treated With Volumetric Modulated Arc Therapy

Purpose: To determine dose constraints that correlate with alopecia in patients treated with photon-based Volumetric Modulated Arc Therapy (VMAT) for primary brain tumors.

Methods: During the treatment planning process, the scalp was drawn as a region of interest. Dose received by 0.1 cc (D_0.1cc), mean dose (D_mean), absolute volumes receiving different doses (V_16Gy, V_20Gy, V_25Gy, V_30Gy, V_35Gy, V_40Gy, and V_43Gy) were registered for the scalp. Alopecia was assessed according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Receiver operating characteristics (ROC) curve analysis was used to identify parameters associated with hair-loss.

Results: One-hundred and one patients were included in this observational study. At the end of radiotherapy (RT), 5 patients did not develop alopecia (D_mean scalp 3.1 Gy). The scalp of the patients with G1 (n = 11) and G2 (n = 85) alopecia received D_mean of 10.6 Gy and 11.8 Gy, respectively. At ROC analysis, V_16Gy20Gy ≥ 5.2 cc were the strongest predictors of acute alopecia risk. Chronic hair-loss assessment was available for 74 patients: median time to recovery from G2 alopecia was 5, 9 months. The actuarial rate of hair regrowth was 98.1% at 18 months after the end of RT. At ROC analysis, V_40Gy43Gy ≥2.2 cc were the strongest predictors of chronic G2-alopecia risk. V_20Gy, V_40Gy, and D_0,1cc were shown to be independent variables according to correlation coefficient r.

Conclusions: V_20Gy and V_40Gy were the strongest predictors for acute and chronic G2 hair-loss, respectively. The low-dose bath typical of VMAT corresponds to large areas of acute but transient alopecia. However, the steep dose gradient of VMAT allows to reduce the areas of the scalp that receive higher doses, minimizing the risk of permanent alopecia.

The application of our dosimetric findings for the scalp may help in reducing the alopecia risk and also in estimating the probability of hair-loss during patient counseling before starting radiotherapy.

Incidence of Chronic Radiodermatitis after Fluoroscopically Guided Interventions: A Retrospective Study

PURPOSE

To assess the incidence and risk factors for chronic radiodermatitis after fluoroscopically guided interventions (FGIs) in high-risk patients.

MATERIALS AND METHODS

Between 2010 and 2016, of 55,782 patients who underwent FGIs, 359 had a risk procedure for skin injury (maximal skin dose > 3 Gy, air kerma > 5 Gy, dose area product [DAP] > 500 Gy.cm², or fluoroscopy time > 60 minutes). Ninety-one of these patients were examined by a dermatologist for radiodermatitis (median time after procedure, 31.2 months [95% confidence interval, 14.2-50.7]). In each case, the clinical features and topography of the skin lesions were recorded and their incidence calculated. The characteristics of the patients and of the FGIs were tested as risk factors.

RESULTS

Eight patients (8.8%) had chronic radiodermatitis; 19 (20.9%) had acute radiodermatitis. Body mass index, DAP value, and air kerma were the only risk factors identified.

CONCLUSIONS

This study shows that chronic radiodermatitis may be considered a frequent side effect in an at-risk population. The lesions are commonly benign, but extensive sclerosis can occur. Patients should be better informed about the side effects and offered a skin exam periodically.

Three Cases of Radiation-induced Temporary Alopecia with Hair Microscopic Examination: "Coudability Hair" Might Not be Specific for Alopecia Areata

Endovascular interventional procedures are widely used for the treatment of intracranial vascular lesions. However, they sometimes produce reversible alopecia, known as radiation-induced temporary alopecia, depending on the radiation dose. Radiation-induced temporary alopecia manifested as rectangular alopecic patches without signs of inflammation, reflects damage to the keratinocytes in the hair matrix of anagen hair follicles, due to the sensitivity of these cells to radiation. The characteristics of radiation-induced temporary alopecia are similar to those of alopecia areata as follows: (1) clinical findings of well-defined alopecic patches and (2) dermoscopic findings of yellow dots, black dots, and short vellus hairs. The two conditions can be distinguished according to whether there is any history of endovascular interventional procedures, and by the shapes of the lesions and the inflammation status on histopathologic examination. A hair microscopic examination is a useful diagnostic tool in patients with hair loss disease, but the features of radiation-induced temporary alopecia have not been well described. Here, we report three cases of radiation-induced temporary alopecia preceded by endovascular procedures, including stent insertion and coil embolization.

The Patient Size Setting: A Novel Dose Reduction Strategy in Cerebral Endovascular Neurosurgery Using Biplane Fluoroscopy

BACKGROUND

In some fluoroscopy machines, the dose-rate output of the fluoroscope is tied to a selectable patient size. Although patient size may play a significant role in visceral or cardiac procedures, head morphology is less variable, and high dose outputs may not be necessary even in very obese patients. We hypothesized that very small patient size setting can be used to reduce dose for cerebral angiography without compromising image quality.

METHODS

Patients who underwent endovascular neurosurgical procedures during the 2015-2016 academic year were identified, and estimated procedural air kerma (AK) was tabulated retrospectively. Technologists were instructed to begin using the very small patient size setting for all procedures performed using our Philips Allura Xper FD20 biplane fluoroscopy system beginning in March 2016. No changes were made in a second procedure room using a Toshiba Infinix system. Student t tests and logistic regression models were used to compare radiation exposure before and after March 1, 2016, for both machines.

RESULTS

For diagnostic cerebral angiograms performed on the Philips system (n = 302), AK was reduced by approximately 17% (1277 vs. 1061 mGy; P = 0.0006.) Changes in table height, total fluoroscopy time, patient weight, and body mass index did not contribute to this difference. No significant change was seen in total AK using the Toshiba system (n = 237). Blinded review by a neuroradiologist did not demonstrate any change in image quality.

CONCLUSIONS

Using the very small patient size reduces fluoroscopy dose by 17% for cerebral angiography without impacting image quality.

Radiation-Induced Alopecia after Endovascular Embolization under Fluoroscopy

Radiation-induced alopecia after fluoroscopically guided procedures is becoming more common due to an increasing use of endovascular procedures. It is characterized by geometric shapes of nonscarring alopecia related to the area of radiation. We report a case of a 46-year-old man presenting with asymptomatic, sharply demarcated rectangular, nonscarring alopecic patch on the occipital scalp following cerebral angiography with fistula embolization under fluoroscopy. His presentations were compatible with radiation-induced alopecia. Herein, we also report a novel scalp dermoscopic finding of blue-grey dots in a target pattern around yellow dots and follicles, which we detected in the lesion of radiation-induced alopecia.

MULTICENTRE COMPARISON OF PATIENT AND DETECTOR DOSE FOR X-RAY-GUIDED EMBOLISATIONS OF ARTERIOVENOUS MALFORMATIONS IN THE BRAIN

Dosimetric benchmarking at four hospitals was performed to investigate incident entrance dose and dose rate on a phantom, and entrance detector dose and dose rate for protocols that are used in routine clinical practice for complex neuroradiological treatment of arteriovenous malformations (AVMs). Measurements were performed with a head phantom that simulates the attenuation and scattering of the human head for the lateral and posteroanterior (PA) views. For fluoroscopy, the measured incident entrance dose rate and entrance detector dose rate were in the range of 44-172 and 0.3-1.3 μGy s(-1), respectively. The pulse rate in fluoroscopy varied between 6.3 and 15 frames per second (fps). For digital subtraction angiography (DSA), incident entrance dose per frame and entrance detector dose per frame were in the range of 744-2800 and 2.6-8.1 μGy/frame, respectively. Optimisation of acquisition parameters such as pulse rate in fluoroscopy, dose per frame in DSA, beam filtration and tube voltage may further improve imaging protocols and lower the patient dose in very complex X-ray-guided embolisations of AVMs in the brain. However, differences in these acquisition parameters observed in this study were relatively small, suggesting that a relatively high degree of optimisation has already been achieved.