Introduction
Splenic neoplasm is a kind of clinically rare
disease, and its incidence rate is lower compared with other common
tumors (1). However, with the changes
in living habits and dietary structure and the accelerated
environmental pollution, there are increasingly more pathogenic
factors of splenic neoplasm, and its incidence rate shows an
increasing trend. Splenic neoplasm is difficult to be detected
early and its misdiagnosis rate is high due to that its clinical
manifestations are not specific (2).
However, with the continuous improvement of imaging technique, the
detection rate of spleen neoplasm is gradually increased.
Consequently, the proportion in the diagnosis and treatment of the
tumors also shows a rising trend, posing a serious threat to the
human life and health (3). The
treatment methods of splenic neoplasm mainly include the splenic
artery embolization, splenectomy, splenic hilar lymph node
dissection (4). The best opportunity
of surgical resection for patients has often been lost because
splenic neoplasm is often in the middle and advanced stage once
diagnosed. Combined with the importance of spleen in immune
function, the spleen preserving treatment methods are gradually
recognized by medical staffs and patients in clinic (5).
The microwave ablation therapy belongs to the
thermal coagulation therapy, characterized by small trauma,
repeatability and definite efficacy, which has gradually become a
preferred method for non-surgical patients, especially those organ
tumor patients with abundant blood supply (6).
The primary purpose of this study was to investigate
the feasibility, safety and effectiveness of ultrasound-guided
percutaneous microwave ablation of splenic neoplasm.
Patients and methods
Patient selection
A total of 62 patients with splenic neoplasm
admitted to our hospital from January 2009 to December 2012 were
selected and randomly divided into control group (n=31) and
observation group (n=31) using the random number table. Inclusion
criteria: i) patients diagnosed as splenic neoplasm via imaging and
pathological examination; ii) patients with malignant tumor; and
iii) patients who signed the informed consent. Exclusion criteria:
i) patients with abnormal coagulation function; and ii) patients
with a previous history of surgery, chemotherapy or radiotherapy.
This study was approved by the Ethics Committee of the Second
People's Hospital of Liaocheng. Signed written informed consents
were obtained from all participants before the study. There were no
statistically significant differences in the general data between
the two groups (P>0.05; Table
I).
 | Table I.Comparisons of general data between
the two groups. |
Table I.
Comparisons of general data between
the two groups.
| Item | Control group
(n=31) | Observation group
(n=31) | t/χ2 | P-value |
|---|
| Sex
(male/female) | 17/14 | 15/16 | 0.065a | 0.799 |
| Age (years) | 30-75 | 30-78 |
|
|
| Average age
(years) | 48.69±8.69 | 49.04±8.53 | 0.160b | 0.873 |
| Type (n, %) |
|
|
|
|
|
Primary | 28 (90.32) | 26 (83.87) | 0.144a | 0.705 |
|
Metastatic | 3 (9.68) | 5 (16.13) |
|
|
Instruments and equipment
KY-2000 water-cooled microwave therapy apparatus
(Nanjing Canyou Medical Technology Co., Ltd. Nanjing, China),
working frequency: 2,450 MHz, output power: 1-100W; low-loss
coaxial cable transmission is connected to electrode, electrode
diameter: 1.9 mm, length: 180 mm, and the microwave gap emission is
10 mm away from the tip, emission gap: 3.0 mm. Lange BTDI-100
peristaltic pump (Baoding Lange Constant Flow Pump Co., Ltd.,
Baoding, China) as the water cycle power pump, flow rate: 30
ml/min; 20°C sterile saline solution as the cooling water.
Ultrasonic instrument: PhilipsiU22 color Doppler
ultrasound diagnostic apparatus (Philips, Amsterdam, Netherlands)
was used for abdominal ultrasound contrast, frequency of variable
frequency probe: 2.5-5.0 MHz, harmonic frequency: 2.5-3.5 MHz,
speed range: 0.06-0.12 m/s. SonoVue (manufacturer: Milan Bracco,
registration no. H20080059, specifications: 59 mg sulfur
hexafluoride gas and freeze-dried powder 25 mg/bottle, Milan,
Italia) was used as the contrast agent.
Treatment protocols for two
groups
Before operation, patients in both groups underwent
the ultrasound contrast and enhanced CT examination to understand
the lesion, and color Doppler ultrasound to detect the blood flow
distribution in splenic artery, creating the conditions for the
selection of microwave spleen ablation approach and ablation area.
The control group was treated with the open ablation: Under the
trachea cannula, the left back of the patient was raised for 30° in
an oblique position, and the right side of the rib margin was cut,
and the abdominal wall was cut layer by layer to expose the spleen.
After that, the microwave ablation electrode was inserted at a
depth according to the ablation area, without damaging the
surrounding organs and hilum of spleen. Under the power of 80 W,
1-7 needles were used for ablation and lasted for 5-50 min for each
needle, and the abdomen was sutured after there was no active
bleeding in the spleen.
The observation group was treated with the
ultrasound-guided percutaneous microwave ablation: The ultrasound
instrument was used to determine the surgical approach. Under the
local anesthesia with 1% lidocaine, the skin in puncture point was
cut and the patient was asked to hold his breath. The microwave
electrode was implanted into the splenic neoplasm under the
guidance of ultrasound, followed by ablation after intravenous
anesthesia with propofol and ketamine. After ablation of each
needle, the needle passage was ablated for 3-5 min until the
ultrasound image showed that the ablation area reached the capsule
and the capsule of spleen was slightly sunken. After the needle was
withdrawn, whether there was free liquid around the spleen or in
the abdominal cavity was scanned. After ablation, the patient was
asked to take a supine position, and sent back to the ward after
there were no vital signs for 2 h.
Evaluation indexes
The splenic hemodynamics of patients in both groups
was detected. The indexes included the arterial velocity of spleen
(splenic arterial trunk, hilum of spleen, and arteries in
intermediate zone and peripheral zone), diameter velocity and flow
of splenic venous trunk were measured. The ablation volume was
observed and measured by two experienced physicians in the
ultrasound department. Ablation volume=total spleen volume before
treatment-retention volume; ablation ratio=ablation volume/total
spleen volume; 1-week shrink ratio=(ablation volume-volume of
ablation area after 1 week)/ablation volume.
A total of 2 ml peripheral blood was drawn from
patients before treatment and at 3, 7 and 14 d after treatment, and
the peripheral blood cell count was detected, including the white
blood cell, red blood cell and platelet counts. The complications
of patients after treatment were observed, including the pleural
effusion, increased blood amylopsin and hemoglobinuria, etc.;
patients were followed up for 5 years, and the survival time and
survival rate of patients in both groups were recorded.
Statistical analysis
Statistical Product and Service Solutions (SPSS)
19.0 (SPSS, Inc., Chicago, IL, USA) software was use for data
processing. Measurement data were presented as mean ± standard
deviation. Comparison between groups was done using One-way ANOVA
test followed by post hoc test (least significant difference).
Enumeration data were presented as percentage, and chi-square test
was used. And Kaplan-Meier survival analysis was performed.
P<0.05 was considered to indicate a statistically significant
difference.
Results
Hemodynamic comparisons
Comparisons of splenic hemodynamic indexes of
patients between the two groups.
The peak velocities of splenic arterial trunk, hilum
of spleen, intermediate zone and peripheral zone in observation
group were significantly lower than those in control group
(P<0.05), and the diameter, velocity and flow of splenic vein
were also obviously lower than those in control group (P<0.05)
(Tables II and III).
| Table II.Comparisons of peak velocities of
splenic artery of patients between the two groups (cm/sec). |
Table II.
Comparisons of peak velocities of
splenic artery of patients between the two groups (cm/sec).
| Group | n | Trunk | Hilum of spleen | Intermediate
zone | Peripheral zone |
|---|
| Observation
group | 31 | 87.73±3.05 | 54.43±3.63 | 35.23±3.56 | 19.58±2.57 |
| Control group | 31 | 94.24±3.37 | 62.86±3.78 | 42.56±3.47 | 22.56±2.48 |
| t |
|
7.947 |
8.956 |
8.209 |
4.646 |
| P-value |
| <0.001 | <0.001 | <0.001 | <0.001 |
| Table III.Comparisons of hemodynamic indexes of
splenic vein between the two groups. |
Table III.
Comparisons of hemodynamic indexes of
splenic vein between the two groups.
| Group | n | Diameter of splenic
vein (min) | Velocity of splenic
vein (ml) | Flow of splenic vein
(n) |
|---|
| Observation
group | 31 | 0.87±0.04 | 25.43±2.53 | 573.23±28.56 |
| Control group | 31 | 0.91±0.07 | 28.86±2.76 | 599.56±28.47 |
| t |
| 2.762 |
5.101 | 3.635 |
| P-value |
| 0.008 | <0.001 | 0.001 |
Peripheral blood cell counts
Changes of peripheral blood cell counts were
explored before treatment and at 3, 7 and 14 days after
treatment.
After treatment, the white blood cell and platelet
counts in both groups were significantly increased compared with
those before treatment, and the counts in observation group were
obviously higher than those in control group (P<0.05). There
were no significant changes in the red blood cell counts in both
groups before and after treatment (P>0.05) (Tables IV, V
and VI).
| Table IV.Comparisons of white blood cell counts
at different time points between the two groups (×109
g/l). |
Table IV.
Comparisons of white blood cell counts
at different time points between the two groups (×109
g/l).
| Group | Before treatment | 3 days after
treatment | 7 days after
treatment | 14 days after
treatment | F-value | P-value |
|---|
| Observation
group | 2.86±0.93 | 5.89±1.03 | 5.58±0.98 | 4.48±0.97 | 18.924b | <0.001 |
| Control group | 2.85±0.92 | 5.14±0.97 | 4.85±0.95 | 3.76±0.95 | 10.612b | <0.001 |
| t |
0.043a |
2.951a |
2.978a |
2.953a |
|
|
| P-value | 0.966 | 0.004 | 0.004 | 0.004 |
|
|
| Table V.Comparisons of red blood cell counts
at different time points between the two groups (×109
g/l). |
Table V.
Comparisons of red blood cell counts
at different time points between the two groups (×109
g/l).
| Group | Before treatment | 3 days after
treatment | 7 days after
treatment | 14 days after
treatment | F-value | P-value |
|---|
| Observation
group | 3.85±0.87 | 3.79±0.83 | 3.63±0.76 | 3.73±0.88 |
1.907b | 0.078 |
| Control group | 3.83±0.85 | 3.74±0.88 | 3.64±0.75 | 3.72±0.87 | 1.893b | 0.081 |
| t | 0.092a | 0.230a | 0.052a | 0.045a |
|
|
| P-value | 0.927 | 0.819 | 0.959 | 0.964 |
|
|
| Table VI.Comparisons of platelet counts at
different time points between the two groups (×109
g/l). |
Table VI.
Comparisons of platelet counts at
different time points between the two groups (×109
g/l).
| Group | Before
treatment | 3 days after
treatment | 7 days after
treatment | 14 days after
treatment | F-value | P-value |
|---|
| Observation
group | 48.26±3.74 | 57.78±3.43 | 78.94±3.23 | 104.29±4.68 | 9.812b | <0.001 |
| Control group | 48.75±3.68 | 49.98±3.42 | 70.36±3.38 |
95.64±4.53 | 6.431b | <0.001 |
| t |
0.520a |
8.966a |
10.218a |
7.394a |
|
|
| P-value | 0.605 | <0.001 | <0.001 | <0.001 |
|
|
Effectiveness of ablation
The ablation volume, ablation ratio and 1-week
shrink ratio in both groups had no significant differences
(P>0.05) (Table VII).
| Table VII.Comparison of ablation effect between
the two groups. |
Table VII.
Comparison of ablation effect between
the two groups.
| Group | n | Ablation volume
(ml) | Ablation ratio
(%) | 1-week shrink ratio
(%) |
|---|
| Observation
group | 31 | 98.73±8.05 | 12.83±5.63 | 7.63±2.56 |
| Control group | 31 | 99.24±8.37 | 13.26±5.78 | 7.56±2.47 |
| t |
| 0.245 | 0.297 | 0.110 |
| P-value |
| 0.807 | 0.767 | 0.913 |
Postoperative complications
Incidence rates of complication after operation were
compared between the two groups. The incidence rate of
complications in observation group (3.23%) was significantly lower
than that in control group (32.26%) (P<0.05) (Table VIII).
| Table VIII.Comparisons of complications after
operation between the two groups (n, %). |
Table VIII.
Comparisons of complications after
operation between the two groups (n, %).
| Group | n | Pleural
effusion | Increased blood
amylopsin | Hemoglobinuria | Incidence rate of
complications | χ2 | P-value |
|---|
| Observation
group | 31 | 0 (0.00) | 0 (0.00) | 1 (3.23) | 1 (3.23) |
|
|
| Control group | 31 | 2 (6.45) | 4 (12.90) | 4 (12.90) | 10 (32.26) | 7.073 | 0.008 |
Survival analysis
The average survival time was (38.45±9.26) months in
observation group and (37.87±9.15) months in control group, and
there was no significant difference between the two groups
(P>0.05). The 5-year survival rate was 61.29% (19/31) in
observation group and 58.06% (18/31) in control group, and there
was no significant difference between the two groups
(P>0.05).
Discussion
Splenic neoplasm is the most serious spleen disease,
but rare in clinic. Traditionally, splenic neoplasm is treated with
splenectomy combined with postoperative radiotherapy and
chemotherapy. However, the efficacy is poor because it is not
sensitive to radiotherapy and chemotherapy, and it can transfer to
the liver and lymph nodes in a short period. Moreover, the
explosive infection, the most dangerous complication, often occurs
after splenectomy. As a result, the prognosis is poor and the
patient's survival rate is low (7).
With the deepening of the understanding of the spleen, it is found
that retaining 25% spleen can maintain the normal function of the
spleen, so minimally invasive treatment of retaining spleen is
increasingly accepted, including partial splenic artery
embolization and thermal ablation, but the former can easily lead
to postoperative liver failure, splenic abscess, portal vein
thrombosis, peritonitis and other complications (8–11). The
energy transfer of microwave ablation is not affected by the loss
of water and carbonization, and less affected by the thermal
precipitation due to blood perfusion. In addition, the ablation
area is larger, so it is widely used in the treatment of
hepatocellular carcinoma with effective effect, but less used in
splenic tumor. However, with the emergence of water-cooled
microwave electrode technique, the traditional microwave ablation
can remove more organ tumors with rich blood supply, so its
feasibility is increased (12).
Until now, there are few reports about hemodynamic
and blood cell comparisons in splenic tumors. But it is important
to note that many patients with splenic tumors are complicated with
hypersplenism (13–15), in which disease, the hemodynamic and
blood cell are used as indicators to evaluate the therapeutic
effect. Interestingly, we found that the hemodynamics and blood
cells in patients with splenic tumors were abnormal, similar to
those with hypersplenism. Accordingly, we compared hemodynamic and
blood cell between the open and percutaneous approaches. The
results of this study showed that the white blood cell and platelet
counts in both groups were significantly increased compared with
those before treatment, and the counts in observation group were
obviously higher than those in control group (P<0.05). However,
there were no significant changes in the red blood cell counts in
both groups (P>0.05).
Peripheral platelet count will be affected by the
high hemodynamic status of the spleen. Generally, the larger the
diameter and flow of splenic vein are, the lower the white blood
cell count will be. The retention theory argues that the portal
vein pressure will affect the retention time of blood cells in the
spleen. The higher the velocity of splenic artery is, the wider the
diameter of splenic vein is and the larger the blood flow of
splenic vein is, the lower the platelet count will be (16). The research results showed that the
peak velocity of splenic artery in observation group was
significantly lower than that in control group after 1 week of
treatment, and the diameter, velocity and flow of splenic vein were
significantly lower than those in control group (P<0.05). The
ablation rate, ablation ratio and 1-week shrink ratio were not
significantly different in the two groups (P>0.05). The reason
may be that ultrasound-guided percutaneous microwave ablation can
monitor the ablation process in real time. In this condition, the
ablation can be more accurate, ablation area overlapping can be
avoided, damage to the surrounding organs can be prevented, and
hemostatic effect can be immediately achieved. Besides, the
water-cooled microwave energy can pass more deeply in the tissues,
forming a greater range of ablation and reducing the arteriovenous
flow and velocity (17). The ablation
effect of ultrasound-guided percutaneous microwave ablation is not
lower than that of open ablation mainly because the spleen blood
flow is rich and fast, greatly affecting the ablation volume. As a
result, the advantage of laparotomy is not prominent.
Ultrasound-guided percutaneous microwave ablation can effectively
reduce the high hemodynamic status of the spleen, thereby
increasing the peripheral blood cell count.
The incidence rates of side effects and
complications in observation group were significantly lower than
those in control group (P<0.05). On the one hand, the ablation
has no imaging guidance, and the distance between the two needles
will be too close or crossed, causing ablation area overlapping.
Moreover, the needle depth is not easy to be controlled, having an
impact on the surrounding organs. What's more, the open microwave
ablation surgery lasts longer and has larger trauma, which is
likely to cause a variety of postoperative complications (18). On the other, the ultrasound-guided
percutaneous microwave ablation can create the conditions for the
single needle ablation of the specific coagulation volume, and
accurately calculate the entry volumes, in which the condition, the
ablation area overlapping can be avoided, resulting in relatively
lower incidence of postoperative complications (19).
The curative effects of ultrasound-guided
percutaneous microwave ablation in the treatment of splenic
neoplasm are significant. This therapy can increase the peripheral
blood cell count and improve the splenic blood flow and coagulation
function, which play a role in the regulation of the patient's body
status. The 5-year survival rate of patients is higher compared
with open ablation and the ultrasound-guided percutaneous microwave
ablation is characterized by the small trauma, lower incidence
rates of adverse reactions and complications and better safety.
In conclusion, ultrasound-guided percutaneous
microwave ablation is characterized by the small trauma, definite
efficacy and fewer complications in the treatment of splenic
neoplasm, which is safe and feasible, and can improve the prognosis
and increase patients' survival rate. However, there were still
many shortcomings in this study; for example, the small sample size
caused bias inevitably, so the sample size should be further
expanded for in-depth research.
Competing interests
The authors declare that they have no competing
interests.
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