Clinical Values of Whole-Body Blood Pool Scans and SPECT for Evaluation of Congenital Vascular Malformation

Abstract

Purpose

This study examines the diagnostic potential of whole-body blood pool scintigraphy (WBBPS) using technetium-99 m-labeled red blood cells to detect congenital vascular malformations (CVMs). It aims to compare its efficacy with traditional imaging techniques such as magnetic resonance imaging (MRI) and ultrasonography (USG), emphasizing its potential advantages in terms of characterization of lesions and capacity for whole-body assessment.

Methods

The efficacy of WBBPS and single-photon emission computed tomography (SPECT)/computed tomography (CT) imaging in diagnosing CVMs, comparing them with USG and MRI results, was evaluated in this retrospective study. Of the 38 patients, 21 were evaluated using these diagnostic methods, with CVMs classified according to the International Society for the Study of Vascular Anomalies guidelines. Also, this study aimed to elucidate the characteristics between WBBPS, SPECT/CT, USG, or MRI findings and their consistency with the final diagnosis.

Results

A total of 21 participants were included in this study, with an average age of 17.7 years old, with female predominance (57.1%). The most common diagnosis was vascular malformations (VMs) (71.4%), followed by combined vascular malformations (14.3%) and lymphatic malformations (9.5%). WBBPS demonstrated positive results in 95.2% of cases. Distinct imaging patterns for each condition were observed, with WBBPS being crucial in locating lesions.

Conclusion

The study findings suggested that WBBPS with SPECT/CT could be helpful in detecting occult VM lesions and ruling out a lymphatic malformation diagnosis. Thus, it can be employed in the evaluation of CVMs.

Introduction

Congenital vascular malformations (CVMs), often present at birth, may not always be immediately apparent, especially when the lesions are located in deeper anatomical structures. These malformations have an overall prevalence of approximately 1.2% to 1.5% among children [1]. CVMs cause a variety of adverse effects, including thrombophlebitis, bleeding, ulcers, pain, and impairment in the joint, bone, and muscle function [1, 2], leading to a decline in the quality of life of patients [1]. Particularly, CVMs that form on the face and neck cause serious and complex psychosocial problems not only to patients but also to their families [1, 3]. Therefore, a method that could improve the patient’s quality of life is warranted through the establishment of an effective treatment plan by accurately identifying the CVM lesion location and depth.

Proposed by Mulliken et al. in 1982, the International Society for the Study of Vascular Anomalies (ISSVA) classification method is a vascular malformation classification method using histochemistry, radiographic characteristics, and electron microscopic characteristics of vascular malformations, which has become the basis for today’s vascular malformation classification system [3–5]. CVMs can be classified according to the ISSVA into the following categories: (1) simple malformation, when only one vessel type is involved; (2) combined malformations, when two or more vessel types are involved; (3) malformations of major named vessels; (4) and vascular malformations associated with other anomalies. Additionally, simple types are stratified into capillary malformation, lymphatic malformation (LM), venous malformation (VM), arteriovenous malformation (AVM), and arteriovenous fistula. Malformations associated with other anomalies refer to syndromes characterized by additional symptoms beyond vascular discrepancy and segmental hypertrophy [5, 6].

Eifert et al. reported that approximately 47% of the CVM patients demonstrated venous predominance in their study and that at least one abnormality of the deep venous system was found [7]. Legiehn and Heran reported an improved quality of life by ethanol sclerotherapy in VM patients [8]. However, for VMs occupying an entire muscle or compartment, the effect of therapy was not satisfactory. In reference to previous studies, determining the exact location and depth of lesions in VM patients is crucial for planning a treatment strategy, and the detection of additional hidden lesions is also warranted to improve treatment effect and quality of life.

Although imaging may not be essential for the clinical diagnosis of superficial and localized lesions, detecting and evaluating deeper lesions is imperative. Magnetic resonance imaging (MRI) and ultrasonography (USG) serve as valuable modalities for the initial CVM assessment. However, owing to the financial costs and constraints in the whole-body scanning capabilities, MRI is limited in identifying additional lesions and regular follow-up assessments [9]. Also, USG is restricted in detecting deep-seated lesions and lesions in close proximity to air or osseous structures [9, 10]. Additionally, USG is operator-dependent and is not appropriate for whole-body evaluation.

One diagnostic approach for CVMs is whole-body blood pool scintigraphy (WBBPS) utilizing technetium-99 m (^99mTc)-labeled red blood cells (RBCs) [9, 11–15]. WBBPS has been shown to provide certain advantages over conventional imaging techniques, such as whole-body assessment capability and cost-efficacy [9, 13].

This current study aimed to evaluate the diagnostic performance and clinical utility of WBBPS using ^99mTc-labeled RBCs in the detection and assessment of CVMs and to compare their efficacy with other conventional imaging modalities. This investigation seeks to determine the potential benefits of WBBPS in terms of lesion characterization and correlation with other diagnostic methods.

Materials and Methods

Patients

In this retrospective study, a total of 38 patients diagnosed with CVMs and underwent WBBPS at Kyungpook National University Hospital between January 1, 2010, and December 30, 2019, were analyzed. Of the total 38 patients, 11 were excluded as they were recipients of sclerotherapy treatment for their CVM lesions prior to WBBPS. Additionally, six patients were excluded because USG or MRI was not performed to compare with WBBPS results. Table 1 provides a detailed overview of the patient’s characteristics.

Table 1.

Patient characteristics

No	Sex	Age	Clinical diagnosis	Longitudinal length	Lesion location	WBBPS	Location on WBBPS	Additional finding on WBBPS	USG findings	MRI findings
1	M	4	Combined vascular malformation	37 cm	Right forearm	Positive	Right forearm, right shoulder	No	Dilated vascular chamber, no flow in the right chest wall, well defined tissue mass in the intramuscular area and hypervascularity with centripetal flow in right wrist dorsum	High fluid contents, hyper contrast enhancement
2	F	15	Combined vascular malformation	56 cm	Left foot	Positive	Left foot	No	Large cavernous channel, stagnant venous flow	Large venous space
3	M	32	Combined vascular malformation	20 cm	Left lateral chest wall	Positive	Left chest wall	No	Infiltrative lesion, soft tissue hypertrophy, arterial and venous hypervascularity, low impedance pattern flow, arteriovenous shunt flow	Dilated vascular space, thrombus formation, fluid signal but with no significant enhancement
4	F	2	VM	28 cm	Right face, Left neck	Positive	Right face, left neck, right lower leg	Yes	Arterial hypervascularity, focal hypodense mass-like lesion, no abnormal vascularity	T2 high-signal intensity and high fluid contents, contrast enhancement
5	F	2	VM	21 cm	Left lower neck	Positive	Left lower neck	No	Anechoic vascular channel, no flow in vascular channel but flow through compression	Multiloculated cystic mass, contrast enhancement
6	F	5	VM	17 cm	Right shoulder, left ankle	Positive	Left ankle, right shoulder (back)	No	Arterial venous hypervascularity, arteriovenous shunt, stagnant venous flow	Localized vascular lesion, signal void due to phlebolith, diffuse contrast enhancement
7	M	7	VM	100 cm	Right lower leg	Positive	Right lower leg	No	Multiple cystic lesion with thrombus component	T2 high-signal intensity high fluid content and hyper contrast enhancement
8	F	10	VM	11 cm	Right upper limb, left foot dorsum	Positive	Left foot	No	Well-demarcated vascular mass, stagnant venous flow, dilated venous space, hypertrophy with arterial hypertrophy	Soft tissue hypertrophy, vascular hypertrophy
9	M	14	VM	72 cm	Left leg	Positive	Left leg	No	Infiltrative lesion, dilated venous chamber	T2 high-signal intensity high fluid content and high contrast enhancement
10	M	18	VM	100 cm	Left flank	Positive	Left flank	No	Infiltrative echogenic lesion, dilated venous chamber, large draining vein	Infiltrative lesion with large draining vein, soft tissue perforation
11	M	22	VM	100 cm	Left shoulder, left forearm	Positive	Left shoulder, left arm	No	Superficial and deep venous malformation, echogenic infiltrative lesion	Tortuous and dilated vascular lesions in subcutaneous and muscle area, T2 high-signal intensity and hyper contrast enhancement in the left axilla, left proximal arm
12	F	23	VM	46 cm	Left face, left thigh	Positive	Left face, left thigh	Yes	Dilated venous channel, stagnant venous flow	High fluid contents, contrast enhancement
13	F	23	VM	59 cm	Right neck, right shoulder	Positive	Right neck, right shoulder	No	Stagnant venous flow, dilated venous chamber	T2 high-signal intensity and enhancement
14	F	25	VM	60 cm	Right elbow	Positive	Right elbow	No	Intramuscular cavernous venous space and stagnant venous flow, suggesting intramuscular VM	Intramuscular vascular lesion, stagnant blood, thrombus formation
15	M	25	VM	63 cm	Left lower leg	Positive	Left lower leg	No	Dilated venous channel, stagnant venous flow, thrombus filling	T2 high-signal intensity and high fluid contents, contrast enhancement
16	F	37	VM	10 cm	Right face	Positive	Right face, right upper arm	No	Stagnant venous flow	T2 high-signal intensity high fluid content and high contrast enhancement
17	F	61	VM	100 cm	Left face	Positive	Left face	No	Intramuscular dilated venous phase, phlebolith, stagnant venous flow	Vascular infiltrative lesion, high fluid contents, inhomogeneous thrombus, and phlebolith
18	M	6	LM	31 cm	Right proximal arm	Negative	-	No	Cystic lesion, no vascular flow, echogenic fluid	Multiple cystic lesion, no contrast enhancement
19	F	4	VM	83 cm	Left hand, left humerus	Positive	Left hand, left forearm	No	Dilated venous space, stagnant venous flow	Deep-seated dilated venous space, contrast enhancement
20	M	8	LM	100 cm	Left thigh	Positive	Left thigh	No	Cystic lesion, no vascular flow, echogenic fluid	Infiltrative lesion in the subcutaneous layer and muscular layer, fluid signal and enhancing portion in the lesion
21	F	28	KTS	100 cm	Right leg	Positive	Right thigh, right hip, right leg	Yes	Dilated venous channel, superficial varicosity, perforator insufficiency	Multiple dilated venous channel

No. the number of patients, M male, F female, WBBPS whole-body blood pool scan, VM venous malformation, SPECT single-photon emission computed tomography, USG ultrasonography, CT computed tomography, PNS paranasal sinuses, MRI magnetic resonance image

Classification of Congenital Vascular Malformation

In the current study, the ISSVA guidelines were used to define simple malformation, combined vascular malformations, and malformations associated with other anomalies. Simple malformations were classified as VM, LM, and AVM. Combined vascular malformation defined the combined vascular malformation. Additionally, the group of malformations associated with other anomalies in this study included only patients with Klippel–Trenaunay syndrome.

Whole-Body Blood Pool Scintigraphy and SPECT

Erythrocytes were labeled using an in vivo method in which stannous pyrophosphate was intravenously injected into patients, and ^99mTc pertechnetate was injected intravenously 30 min thereafter. When the injection was completed, a whole-body blood pool planar image was obtained. Using a dual-head gamma camera equipped with a low-energy high-resolution collimator, a 256 × 1024 matrix whole-body blood pool planar image was acquired. This was followed by a non-contrast, low-dose CT scan. Subsequently, a SPECT acquisition was performed using a 120-projection, 360° camera rotation with a dual-head gamma camera. Images were iteratively reconstructed to a 128 × 128 matrix (OSEM, four iterations, ten subsets) with scatter and CT-based attenuation correction, including a Butterworth filter with a critical frequency of 0.48 and power of 10.00. The SPECT reconstruction was conducted on a Xeleris 4 workstation (GE Healthcare, Waukesha, WI, USA). All planar and SPECT/CT images were independently read by two experienced nuclear medicine physicians. Through visual assessment, positive uptake was determined.

Comparative Diagnostic Methods

All patients underwent planar and SPECT/CT imaging, and these patients underwent USG, MRI, or both concurrently. Thus, the analysis was performed to determine if the WBBPS planar and SPECT/CT imaging findings in all patients were consistent with USG or MRI findings and whether these findings were consistent with the final diagnosis.

Ethics

All procedures in the current study were performed according to the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Because this is a retrospective review of the data, the requirement for an informed consent was waived by the KNUH institutional review board (No. 2023–07-028).

Results

Patient Characteristics

The study population included 21 participants with a mean age of 17.7 years and a standard deviation of 14.5 years. Sex distribution leaned toward females with a count of 12 as opposed to nine males. The average size of the studied lesions was 57.9 cm with a standard deviation of 33.6 cm. VM comprised the majority of the diagnoses, making up 71.4% of cases, followed by combined vascular malformation at 14.3%, LM at 9.5%, and a single case of Klippel–Trenaunay syndrome at 4.8%. WBBPS imaging revealed positive results in 95.2% of cases, with only 4.8% showing negative results. For the USG findings, VMs were at 61.9%, followed by combined vascular malformation at 23.8%. For the MRI findings, VM was at 66.7%, followed by combined vascular malformation at 28.6%. Three cases (14.3%) showed hidden VM lesions on WBBPS which were not recognized prior to imaging. Of the patients with additional lesions, two cases had new confirmed VMs. One of the two additional findings was a VM lesion around the scar, which previously had sclerotherapy. The other case was grossly unseen during the first visit and at the time point during the performance of WBBPS. In Table 2, descriptive statistics of the patients are summarized.

Table 2.

Descriptive statistics

Variables	Mean ± SD or %	Number (N)
Sex		21
Female	12 (57.1%)
Male	9 (42.9%)
Age	17.7 ± 14.5	21
Size	57.9 ± 33.6	21
Diagnosis		21
LM	2 (9.5%)
Combined vascular malformation	3 (14.3%)
VM	15 (71.4%)
KTS	1 (4.8%)
WBBPS		21
Negative	1 (4.8%)
Positive	20 (95.2%)
USG		21
AVM	1 (4.8%)
LM	2 (9.5%)
Combined vascular malformation	5 (23.8%)
VM	13 (61.9%)
MRI		21
LM	1 (4.8%)
Combined vascular malformation	6 (28.6%)
VM	13 (61.9%)
Additive lesions detected by WBBPS		21
Yes	3 (14.3%)
No	18 (85.7%)

WBBPS whole-body blood pool scan, VM venous malformation, LM lymphatic malformation, KTS Klippel–Trenaunay syndrome, SPECT single-photon emission computed tomography, USG ultrasonography, CT computed tomography, PNS paranasal sinuses, MRI magnetic resonance image

Imaging Patterns of Congenital Vascular Malformations Using Conventional Imaging and WBBPS

Imaging characteristic analysis using USG, MRI, and WBBPS has uncovered distinct patterns for VM, combined vascular malformations, and LM.

In VM cases, USG typically illustrated dilated vascular chambers, stagnant venous flow, and arterial hypervascularity, while MRI predominantly demonstrated T2 high-signal intensity, high fluid content, and contrast enhancement. Most notably, WBBPS played a critical role, predominantly demonstrating positive findings and in some cases revealing lesions at multiple locations.

Notably, patient 4 manifested with airway obstruction attributed to a neck mass during her first visit. SPECT/CT was utilized for the delineation of the lesions in the right face and left neck. The VM lesion on her right leg, although not visibly apparent, was discernible via WBBPS. This right leg lesion was visually confirmed 9 months after the WBBPS was conducted (Fig. 1). Conversely, patient 12 underwent sclerotherapy with VM on the left thigh 3 years prior, and an increase in the blood pool was noted in this area in WBBPS. Concerning the increased blood pool observed in the left thigh, SPECT/CT was used to verify the location and depth of the lesion. Confirming the lesion via MRI, lesions revealing high-signal intensity were identified in both T1 and T2, which are considered to be residual scars due to treatment. Additionally, increased gadolinium contrast was confirmed in the periphery (Fig. 2). This pattern suggests the presence of residual lesions, as vascular components persist in the treated area, with no further examination or treatment conducted thereafter.

Fig. 1.

A 24-month-old female sought an evaluation for a mass in her face and neck. WBBPS revealed increased blood pooling in the right face (a, black arrow), left neck (a, black arrow), and right lower leg (a, red arrow), indicating VM with involvement in multiple sites. The right lower extremity finding was incidental during WBBPS. To delineate the exact locations, SPECT/CT was utilized. SPECT/CT images, both transaxial (b, c) and coronal (d, e), detailed the extent of VM in the right masticatory muscle, floor of the mouth, and the left neck. Facial T2-weighted MRI showed high-signal intensity in the left neck (f), and gadolinium-enhanced T1 MRI revealed partial enhancement (g) in the left neck, consistent with VM. Tibia T2-weighted MRI displayed high-signal intensity along the muscles in the right lower leg (h), with gadolinium-enhanced T1 MRI showing high-signal intensity and enhancement (i), indicative of VM. The lesion in the right lower leg was visually confirmed 9 months after WBBPS (j), highlighting the clinical importance of SPECT/CT in assessing and understanding the extent of VMs. WBBPS, whole-body blood pool scan; VM, venous malformation; SPECT, single-photon emission computed tomography; CT, computed tomography; MRI magnetic resonance imaging

Fig. 2.

A 23-year-old female presented for an evaluation of a left cheek mass. WBBPS revealed increased blood pooling in the left cheek (a, black arrow), consistent with VM, and an unexpected incidental finding of increased blood pooling in the left thigh (a, blue arrow). To determine the depth and extent of both lesions, SPECT/CT was employed. Coronal (b, c) and transaxial (d, e) SPECT/CT images of the face revealed a localized increase in blood pooling within the left masseter muscle. USG of the left cheek revealed dilated venous space with stagnant venous flow around the left masseter muscle, suggesting VM (f). PNS T2-weighted MRI (g) showed a high-signal intensity lesion in the left masseter muscle, and gadolinium enhancement T1 MRI (h) revealed high fluid content with contrast enhancement in the lesion of the left cheek and the left masseter muscle, suggesting VM. Concerning the increased blood pool observed in the left thigh, SPECT/CT was used to verify the location and depth of the lesion (i, j). A T2-weighted MRI (k) for the lesion confirmed a high-signal change lesion accompanied by a surrounding low-signal infiltrative lesion, and an internal high-signal intensity was also observed on gadolinium-enhanced MRI (l), with the surrounding infiltrative lesions observed with good contrast enhancement. This pattern suggests the presence of residual lesions, as vascular components persist in the treated area, with no further examination or treatment conducted thereafter. This case underscores the clinical significance of SPECT/CT in precisely mapping and evaluating the extent of VMs, providing essential insights for diagnosis and treatment planning. WBBPS, whole-body blood pool scan; VM, venous malformation; SPECT, single-photon emission computed tomography; USG, ultrasonography; CT, computed tomography; PNS, paranasal sinuses; MRI, magnetic resonance image

Similarly, for combined vascular malformations, while USG exhibited dilated vascular chambers, infiltrative lesions, soft tissue hypertrophy, and arterial and venous hypervascularity and MRI displayed high fluid content, hyper contrast enhancement, dilated vascular space, and thrombus formation, WBBPS was essential in locating the lesions, frequently congruent to the physical manifestations of the condition. Additionally, SPECT/CT can be utilized to the extent and depth of the lesions in the trunk. These lesions are compatible with the lesions showing on MRI. In patients with Klippel–Trenaunay syndrome (KTS), a wide range of lesions may emerge as combined vascular malformations (Fig. 3).

Fig. 3.

A 34-year-old female, diagnosed with KTS, underwent WBBPS and SPECT/CT. WBBPS demonstrated increased blood pool activity along the left posterior trunk, left abdominal wall, left pelvic cavity, and left lower extremity (a). To thoroughly assess the extent and depth of these lesions, SPECT/CT was conducted. Coronal (b) and transaxial (c) SPECT/CT images displayed diffuse infiltrations with multiple lobulated mass lesions with increased blood pooling along the left posterior trunk, left abdominal wall, left pelvic cavity, and left lower extremity. Further imaging with gadolinium-enhanced T1- and T2-weighted MRI displayed these diffuse infiltrative lesions, with distinct gadolinium enhancement (d) and pronounced T2 high-signal intensity (e), suggesting a combined vascular malformation. These findings are indicative of a condition possibly associated to or concurrent with other anomalies, such as those observed in KTS. This case underscores the critical role of SPECT/CT in offering detailed and precise imaging, crucial for the comprehensive evaluation and understanding of diffusely infiltrative lesions in the whole-body like KTS. WBBPS, whole-body blood pool scan; KTS, Klippel-Trenaunay syndrome; SPECT, single-photon emission computed tomography; CT, computed tomography; MRI, magnetic resonance image

For LM, USG commonly highlights cystic lesions, the absence of vascular flow, and echogenic fluid, while MRI depicted multiple cystic lesions and deep-seated dilated venous spaces with no contrast enhancement. Interestingly, WBBPS findings were negative; however, it is noteworthy that in cases where LMs infiltrated the surrounding tissues, an increased blood pool could be noted around the LM lesions, emphasizing the significance of WBBPS in identifying lesion locations and their impact. In this study, LM lesions were not revealed on WBBPS, as observed in patient 18 (Fig. 4); however, an increased blood pool was noted when there was a concomitant vascular component, as observed in patient 20 (Fig. 5). The characteristic patterns and findings identified for each lesion in this study are summarized in Table 3.

Fig. 4.

A 6-year-old male came in for evaluation of his right arm mass. WBBPS demonstrated no significant blood pooling in the right arm, indicating the absence of substantial blood pooling where the mass was located (a). An accumulation of the tracer was observed in the left lower leg, attributed to the site of tracer injection (a, dashed arrow). To further evaluate, SPECT/CT was performed and similarly revealed no notable blood pooling in the right arm (b, c). T2-weighted MRI exhibited high-signal intensity (d, white arrow), and gadolinium enhancement T1 MRI (e, white arrow) showed minimal enhancement in the right arm, indicative of LM. Additionally, Doppler USG revealed multiple cystic lesions involving the subcutaneous fat layer without blood flow, further supporting the LM diagnosis (f, g, white arrow). The utilization of SPECT/CT, in this case, highlights its significance in providing clear, confirmatory imaging that aids in differentiating LM from other vascular anomalies, especially in the absence of typical blood pooling patterns. WBBPS, whole-body blood pool scan; LM, lymphatic malformation; SPECT, single-photon emission computed tomography; CT, computed tomography; MRI, magnetic resonance image; USG, ultrasonography

Fig. 5.

An 8-year-old boy came in with a chief complaint of a left hip mass. In the T2-weighted MRI, a vascular component showing high signal intensity was observed in the surrounding area, and a cystic mass displaying signal intensity of internal fluid level was observed in the left hip (a, b). Contrast enhancement of peripheral vascular components was observed on gadolinium-enhanced MRI (c, d). In the Doppler USG, a cystic lesion containing echogenic fluid was identified, but no internal vascular flow was observed (e, f). These findings indicate LM. In WBBPS, a lesion displaying a central photon defect and peripheral tracer accumulation was identified in the left hip (g). In SPECT/CT, photon defects were observed in the cystic portion, and tracers accumulated in areas representing peripheral vascular components (h, i). WBBP/S, whole-body blood pool scan; LM, lymphatic malformation; SPECT, single-photon emission computed tomography; CT, computed tomography; MRI, magnetic resonance image; USG, ultrasonography

Table 3.

The pattern of USG and MRI and the findings of WBBPS through image analysis

DIAGNOSIS	USG PATTERNS	MRI PATTERNS	WBBPS FINDINGS
VM	Dilated vascular chambers, stagnant venous flow, arterial hypervascularity, anechoic vascular channels	T2 high-signal intensity, high fluid contents, contrast enhancement, signal void due to phlebolith	Predominantly positive findings, with some patients demonstrating lesions at multiple locations
LM	Cystic lesions, no vascular flow, echogenic fluid	Multiple cystic lesions, no contrast enhancement, deep-seated dilated venous space	Both positive and negative findings were noted, with the lesion locations corresponding to the physical manifestations
COMBINED VASCULAR MALFORMATION	Dilated vascular chambers, infiltrative lesions, soft tissue hypertrophy, arterial and venous hypervascularity	High fluid contents, hyper contrast enhancement, dilated vascular space, thrombus formation	Predominantly positive findings, with lesions usually located at the place of physical manifestation

WBBPS whole-body blood pool scan, VM venous malformation, LM lymphatic malformation, SPECT single-photon emission computed tomography, USG ultrasonography, CT computed tomography, MRI magnetic resonance image

Discussion

Since the 1980s, studies have been conducted on whole-body blood pool imaging for CVM lesions [15–17]. Murata et al. reported that WBBPS demonstrated a high diagnostic sensitivity of 91% in neck hemangioma [15]. Roy et al. elucidated a case where SPECT/CT contributed to multiple hemangioma detection on WBBPS images [14]. These studies reveal that WBBPS and SPECT/CT are helpful for the CVM assessment. However, in CVM diagnosis, conventional images such as USG and MRI remain the mainstream, and there is paucity of descriptions of the correlation with WBBPS images and the differences between WBBPS and other images.

MRI is a noninvasive modality and is considered the most optimal method of determining the exact nature of a CVM, such as the flow characteristics of the lesion and the degree of cellularity [9, 18]. However, despite these advantages, MRI can be expensive and limited in scope, rendering it prohibitively expensive for patients to undergo a full-body screening at one time period [9, 19–21].

WBBPS, a less expensive imaging modality than MRI and has a higher diagnostic sensitivity for CVM lesions, can provide useful information for the initial patient evaluation [9]. WBBPS is clinically useful as it allows for whole-body imaging at one time, and CVMs can be strongly suspected if the imaging demonstrates increased blood pooling [9, 15, 22]. In previous studies, WBBPS has been revealed as a cost-effective and highly accurate method for the diagnosis and screening of patients with congenital CVMs [9].

In the present study, three cases had additional lesions that were identified using WBBPS. To evaluate the newly discovered blood pool activity, SPECT/CT, MRI, or USG were mobilized, which resulted in the discovery of a new VM lesion 9 months after WBBPS in one case. The depth and extent of the new lesions were confirmed via SPECT/CT. The lesion location and characteristics identified through SPECT/CT were consistent with MRI findings.

In a previous study, blood pool scintigraphy showed a high sensitivity in patients with hemangiomas, but a somewhat lower specificity (67%) owing to the possibility of false positives [15]. For patients with false-positive CVMs evaluated in this study, SPECT/CT accurately localized the lesion but failed to determine the nature of the lesion, such as whether it was a new CVM lesion or scarring from prior treatment. For these lesions, MRI or USG allowed to determine the nature of the lesion, suggesting that the low specificity of WBBPS may be compensated for via other imaging modalities.

Interestingly, only one true negative was found in this study, and this patient was diagnosed with LM. LM can be distinguished from other VMs through the absence of abnormal blood pooling in the WBBPS, and this differentiation between LM and VM is a clinically important finding [9, 23]. When managing VM, the primary approach involves the use of absolute ethanol, whereas the management of LM predominantly includes other sclerosants such as doxycycline, and the utility of physical therapy for associated lymphedema [20, 24]. This different pattern between VM and LM in WBBPS can be an important indicator in the differentiation of the lesions, given the varying treatments for the two lesions. Thus, if WBBPS does not reveal abnormal blood pooling in the patient’s lesions, VM can be ruled out, which is helpful in determining the treatment course.

This study has several limitations. (1) The study involved a small number of participants, which makes it limited in scope. To substantiate the imaging patterns and enhanced detection capacities of WBBPS and SPECT/CT for differentiating CVMs, expanded investigations involving more patients are essential. (2) The study only compared the radiological patterns of WBBPS with other imaging tests, and the value of WBBPS in follow-up processes was not determined. (3) Additionally, the study proceeded by comparing with other imaging tests without confirming the precise lesion pathology, which also renders the research limited. Further research should focus on evaluating the precision of differential diagnoses in CVMs by correlating the results of subsequent imaging with pathological histological data. Additionally, it is important to conduct more studies to explore the treatment approaches for CVMs in relation to their established pathological characteristics.

Conclusion

The study findings suggested that WBBPS with SPECT/CT might be helpful in identifying hidden VM lesions and ruling out the diagnosis of LM. Thus, it can be employed in the evaluation of CVMs.

Author Contribution

Material preparation and data collection were performed by Junik Son. The first draft of the manuscript was written by Junik Son, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Data Availability

The datasets for this study will not be made publicly available because this study is not open for public use.

Declarations

Ethics Approval and Consent to Participate

This study was performed in accordance with the ethical standards laid down in the Helsinki Declaration of 1964 and its later amendments or comparable ethical standards. Because this is a retrospective review of the data, the requirement for informed consent was waived by the KNUH institutional review board (No. 2023–07-028).

Consent for Publication

Not applicable.

Conflict of Interest

Junik Son, Chae Moon Hong, Jaetae Lee, Ho Yun Chung, and Byeong-Cheol Ahn declare no competing interests.