The use of 3D power Doppler ultrasound in the quantification of blood vessels in uterine fibroids: feasibility and reproducibility

How to use power Doppler ultrasound in transvaginal assessment of uterine fibroids

Measuring vascularization in uterine fibroids is important for their diagnosis, treatment and prognosis. Vascularization can be measured by power Doppler ultrasound. The power Doppler signal depends on fibroid characteristics and on a variety of ultrasound-machine settings. Literature describing which machine settings influence the power Doppler signal is limited. Each manufacturer names settings and presets at their own discretion, with little information available publicly. Consistency of machine settings is important for correct interpretation of images in daily practice and is essential in yielding reproducible data for research. The aims of this paper, drawing from both a literature search and semistructured interviews with ultrasound-machine engineers and clinical experts in gynecological ultrasound, were: (1) to provide comprehensive background information on ultrasound physics and fibroid characteristics; (2) to present an overview of machine settings relevant to both two- and three-dimensional power Doppler, including power Doppler frequency, pulse repetition frequency, gain, wall-motion filter, acoustic power, persistence and signal rise; and (3) to provide a step-by-step tutorial on the optimal settings for vascular evaluation of uterine fibroids using power Doppler. The step-by-step tutorial comprises six steps to optimize the power Doppler signal, create a preset and acquire a reliable three-dimensional volume. This step-by-step tutorial should help research groups and clinicians to use power Doppler correctly and reproducibly in the evaluation of uterine fibroids. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Fibroid vascularisation assessed with 3D Power Doppler as predictor for fibroid related symptoms and quality of life; a pilot study

Background

Uterine fibroids present differently, from well vascularised up to calcified, with some causing heavy menstrual bleeding (HMB).

Objectives

To investigate the association between fibroid vascularisation and HMB, other fibroid related symptoms and quality of life (QOL).

Materials and Methods

A single centre pilot study was carried out in the Netherlands. Women with a maximum of two fibroids who chose expectant management were included. 3D sonography including power doppler was performed at baseline and at 3, 6 and 12 months follow up. Women were asked to complete the Pictorial Blood Assessment Chart (PBAC) and Uterine Fibroid Symptom and Quality of Life (UFS-QOL) questionnaires at every visit.

Main outcome measure

The association between fibroid vascularisation and HMB.

Results

53 women were included in the study. Baseline fibroid vascularisation, measured as vascular index (VI) is associated with PBAC score; a 1% higher VI at baseline leads to an 11 point increase in PBAC score over time (RC 10.99, p=0.05, 95% CI -0.15 – 22.12). After correction for the baseline variables ethnicity and fibroid type the association becomes stronger (P<0.05). Fibroid volume at baseline and HMB are also associated: a 1 cm3 larger fibroid leads to 0.6 points increase in PBAC score over time (RC 0.56, p=0.03, 95% CI 0.05 – 1.07).

Conclusions

This study highlights that both fibroid vascularisation and fibroid volume may be associated with an increase in menstrual blood loss, other fibroid related symptoms and QOL over time.

What is new?

We used 3D power doppler to predict symptomatic fibroids.

Uterine fibroid vascularization: from morphological evidence to clinical implications

Uterine fibroids are the most common cause of solid pelvic tumours, occurring in 20-30% of fertile women and presenting clinical complications that seriously affect women's health. They commonly cause severe symptoms, such as heavy, prolonged menstrual bleeding and anaemia. The study of microscopic and macroscopic vascular aspects of uterine fibroids is important for understanding the clinical manifestations of uterine fibroids, for predicting the effectiveness of alternative treatments to surgery, i.e. uterine artery embolization, for improving surgery outcomes and for carrying out a differential diagnosis with other benign conditions, e.g. adenomyosis, or malignancy, e.g. leiomyosarcoma, and to develop new therapeutic approaches. In this review, current knowledge of how the vascular network and angiogenesis are implied in the formation of uterine fibroids and in the pathogenesis of related symptoms is explored, and evidence on the role of ultrasound in evaluating fibroid vascularization is summarized. This review combines anatomical, morphological and biomolecular information related to angiogenic mechanisms with diagnostic and clinical information, highlighting the various interconnections. Uterine and fibroid vascularization need further investigation to gain a deeper understanding of the pathogenetic elements that lead to the formation of uterine fibroids and their clinical manifestations.

Differences in fibroid vascularity after three months of pre-treatment with leuprolide acetate or ulipristal acetate: A pilot study

OBJECTIVES

To investigate differences in volume and fibroid vascularity expressed in vascular index after three months of (pre-)treatment with leuprolide acetate (LPA) or ulipristal acetate (UPA).

STUDY DESIGN

Prospective pilot study of 23 premenopausal women with uterine fibroids. Patients who started with LPA or UPA and had at least one fibroid with a size between 3 and 12 cm, were included consecutively. Per patient one fibroid was evaluated. The ultrasound was performed at baseline and after three months using LPA or UPA using a standardized protocol. 3D scans were evaluated using VOCAL software to calculate outcomes of volume, vascular index (VI) without shell ("shell off") and of the inner shell.

RESULTS

Four patients in the LPA group were additionally excluded from analyses due to insufficient quality of 3D scans. In the ten remaining patients (pre-)treated with LPA both volume and vascular indices of the fibroid reduced significantly after three months from a median of 224.3 cm³ (IQR 338.0) to 124.8 cm³ (IQR 186.1) (p = 0,05); median VI fibroid (shell off) reduced from 4.30 (IQR 4.72) to 0.93 (IQR 1.54) (p = 0,05); and VI inner capsule from 6.34 (IQR 7.51) to 1.28 (IQR 2.13) (p = 0,05). After UPA (n = 9) changes in fibroid volume and vascular indices did not reach statistical significance. Volume reduced from 248.5 cm³ (IQR 271.9) to 140.7 cm³ (IQR 209.4) (p > 0,05); median VI fibroid (shell off) from 2.97 (IQR 3.81) to 2.90 (IQR 4.82) (p > 0,05); and VI inner capsule from 2.56 (IQR 7.48) to 2.89 (IQR 4.83) (p > 0,05). A strong positive correlation was found between the VI of the fibroid (shell off) at baseline with the volume change after three months of LPA use (LPA r = 0.636, p = 0.048, 95% CI = -0.03 - 1.00).

CONCLUSION

In this pilot study we observed a consistent and statistically significant decrease in VI and fibroid volume after three months of LPA treatment in patients with uterine fibroids. The decrease in fibroid volume and VI was less consistent after UPA use. The strong correlation between the VI at baseline and volume reduction, may in theory be used to predict the volume reduction after LPA.

Use of Contrast-Enhanced Ultrasound in the Assessment of Uterine Fibroids: A Feasibility Study

Contrast-enhanced ultrasound (CEUS) is an innovative ultrasound technique capable of visualizing both the macro- and microvasculature of tissues. In this prospective pilot study, we evaluated the feasibility of using CEUS to visualize the microvasculature of uterine fibroids and compared CEUS with conventional ultrasound. Four women with fibroids underwent gray-scale ultrasound, sonoelastography and power/color Doppler scans followed by CEUS examination. Analysis of CEUS images revealed initial perfusion of the peripheral rim, that is, a pseudo-capsule, followed by enhancement of the entire lesion through vessels traveling from the exterior to the interior of the fibroid. The pseudo-capsules exhibited slight hyper-enhancement, making a clear delineation of the fibroids possible. The centers of three fibroids exhibited areas lacking vascularization, information not obtainable with the other imaging techniques. CEUS is a feasible technique for imaging and quantifying the microvasculature of fibroids. In comparison with conventional ultrasound imaging modalities, CEUS can provide additional diagnostic information based on the microvasculature.

3D Power Doppler vascular indices as a novel technique in assessing the outcome of minimally invasive techniques in uterine fibroids treatment

Uterine fibroids are considered to be the most frequent female benign tumours. The most common reported symptoms of fibroids are heavy menstrual bleeding and painful menstruation, pelvic pain, urinary problems, constipation, as well as infertility and recurrent pregnancy loss. The mainstay of fibroid treatment is surgery, but nowadays minimally-invasive techniques are growing in popularity. Vascularity of fibroids may play a role in the outcome of these techniques, which is why it is important to find an objective, reproducible technique to measure the vascularization before and after the procedure. The 3D Power Doppler vascular indices (3DPDVI) allow objective assessment of vascularization in the entire volume of the tumour. Initially this technique was mostly used in experimental imaging phantoms, but recently many studies focus on the clinical utility of this technique. Power Doppler allows to obtain information on vascularity in the area of interest, while 3DPDVI can be objectively calculated by the Virtual Organ Computer-aided AnaLysis (VOCAL™) software. 3DPDVI showed high reproducibility in most of the studies. This technique has an important role in monitoring the outcome of minimally invasive procedures in fibroid treatment, because they affect vascularity of the tumours. Although there are some limitations of 3DPDVI, it seems that their application may be an effective tool in objective assessment of vascularity of fibroids. However further studies are required to consolidate the usage of 3DPDVI in clinical practice.

Pelvic Blood Flow Predicts Fibroid Volume and Embolic Required for Uterine Fibroid Embolization: A Pilot Study With 4D Flow MR Angiography

OBJECTIVE

We report here an initial experience using 4D flow MRI in pelvic imaging-specifically, in imaging uterine fibroids. We hypothesized that blood flow might correlate with fibroid volume and that quantifying blood flow might help to predict the amount of embolic required to achieve stasis at subsequent uterine fibroid embolization (UFE).

MATERIALS AND METHODS

Thirty-three patients with uterine fibroids and seven control subjects underwent pelvic MRI with 4D flow imaging. Of the patients with fibroids, 10 underwent 4D flow imaging before UFE and seven after UFE; in the remaining 16 patients with fibroids, UFE had yet to be performed. Four-dimensional flow measurements were performed using Arterys CV Flow. The flow fraction of the internal iliac artery was expressed as the ratio of internal iliac artery flow to external iliac artery flow and was compared between groups. The flow ratios between the internal iliac arteries on each side were calculated. Fibroid volume versus internal iliac flow fraction, embolic volume versus internal iliac flow fraction, and embolic volume ratio between sides versus the ratio of internal iliac artery flows between sides were compared.

RESULTS

The mean internal iliac flow fraction was significantly higher in the 26 patients who underwent imaging before UFE (mean ± standard error, 0.78 ± 0.06) than in the seven patients who underwent imaging after UFE (0.48 ± 0.07, p < 0.01) and in the seven control patients without fibroids (0.48 ± 0.08, p < 0.0001). The internal iliac flow fraction correlated well with fibroid volumes before UFE (r = 0.7754, p < 0.0001) and did not correlate with fibroid volumes after UFE (r = -0.3051, p = 0.51). The ratio of embolic required to achieve stasis between sides showed a modest correlation with the ratio of internal iliac flow (r = 0.6776, p = 0.03).

CONCLUSION

Internal iliac flow measured by 4D flow MRI correlates with fibroid volume and is predictive of the ratio of embolic required to achieve stasis on each side at subsequent UFE and may be useful for preprocedural evaluation of patients with uterine fibroids.

3D power Doppler in uterine fibroids; influence of gain, cardiac cycle and off-line measurement techniques

This study answers the question of whether ultrasound machine settings and the cardiac cycle can influence 3D power Doppler (3D PD) indices in the evaluation of uterine fibroid vascularisation. These parameters were reported to affect the vascular indices and cause undesired variation. 3D PD ultrasound was performed using three different gain settings: a fixed predetermined gain (50 dB), a higher gain (65 dB) and an individualised subjectively most optimal gain. Two consecutive 3D PD sweeps were taken to evaluate the effect of the cardiac cycle. A predetermined most optimal fixed gain setting was not different from the individually most optimal chosen gain in vascular assessment of fibroids. A higher gain corresponded with a significantly higher vascular index (VI). Potential variation during the cardiac cycle does not disturb the VI in fibroids.

Fibroid vascularisation assessed with three-dimensional power Doppler ultrasound is a predictor for uterine fibroid growth: a prospective cohort study

OBJECTIVE

To analyse fibroid vascularisation measured with three-dimensional (3D) power Doppler in relation to absolute fibroid volume change during 12 months of follow up and in relation to fibroid growth rate per year.

DESIGN

A prospective cohort study was performed between March 2012 and March 2014.

SETTING

Outpatient clinic of the VU medical centre, Amsterdam.

POPULATION OR SAMPLE

All premenopausal women diagnosed with a maximum of two fibroids with expectant management were consecutively included.

METHODS

Three-dimensional ultrasound including power Doppler was performed at baseline, 3, 6 and 12 months. Volume and vascular parameters were calculated using VOCAL software.

MAIN OUTCOME MEASURES

The relationship between vascular index (VI) at baseline and fibroid volume over time was analysed using linear mixed model analyses for repeated measurements. Second, the relationship between VI at baseline and fibroid growth rate per year was calculated using linear regression analyses. Analyses were adjusted for possible confounders.

RESULTS

In all, 66 women (mean age 42 years) completed 12 months of follow up without treatment. Baseline fibroid vascularisation (VI) measured with 3D power Doppler is correlated with fibroid volume at 12 months (P = 0.02 ). An increase of 1% in VI at baseline was associated with a 7.00-cm³ larger fibroid volume at 12 months. Furthermore, vascularisation was also associated with fibroid growth rate per year (P = 0.04).

CONCLUSION

In women with uterine fibroids without therapy, baseline vascularisation (VI) measured with 3D power Doppler is correlated with absolute fibroid volume change at 12 months and with fibroid growth rate per year.

TWEETABLE ABSTRACT

Fibroid vascularisation correlates with absolute fibroid volume change and fibroid growth rate per year.