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ECR 2018 / C-2456
Magnetic resonance imaging features of hemostatic agents and tissue sealants after partial nephrectomy
Congress: ECR 2018
Poster No.: C-2456
Type: Educational Exhibit
Keywords: Kidney, MR, MR-Diffusion/Perfusion, Diagnostic procedure, Surgery, Haemorrhage, Biological effects
Authors: H. Sahin, A. I. Biranci, A. Cakir, Y. Pekcevik, E. Kısa, Z. Kozacioglu; Izmir/TR
DOI:10.1594/ecr2018/C-2456

Findings and procedure details

We reviewed our institutional data base for patients with partial nephrectomy operation including both open PN and laparoscopic PN between January 2013 and June 2017. Of the overall 38 patients (age range 37-76 years-old) with PN, 32 patients had pathological diagnosis of renal cell carcinoma and others had benign lesions including oncocytoma and hydatid cyst. In all patients one or more hemostatic agent or tissue sealant were used for promoting hemostasis. All patients were followed-up via magnetic resonance imaging (MRI) between 3-36 months. Also, 4 types of those hemostatic agents coated with blood were fixed in a carrageenan gel and studied by different MRI sequences at the second week and third month.

 

Topical hemostatic and sealing agents currently used in surgical procedures ( Table 3 )

Classification according to mechanism of action [3]:

1.    Active hemostatic agents (fibrin sealants):

·         These agents participate at the end of coagulation cascade to form a fibrin clot.

·         They are also known as “adhesive hemostats” because of their hemostatic and tissue sealing action.

·         Currently, fibrin sealants are the most effective hemostatic adhesive agents available for surgical practice [3].

·         Products are: TISSEEL®, TISSUCOL®, EVISEL®, Hemaseel®, Tachosil®

·         They may cause possible allergic reactions

·         They are not clearly seen in control MRI’s of the patients since they do not form a mass.

2.    Passive hemostatic agents

·         These agents are not biologically active

i.              Topical hemostats

·         They are absorbable agents that can be used alone or in combination with fibrin sealants

·         They provide platelet activation and aggregation when directly applied to the bleeding tissue

·         They can absorb body fluid several times their own weight

·         Collagen based agents, gelatin based hemostatic agents and cellulose based agents [regenerated oxidized cellulose (ROC)] are in this group

·          They are bovine, equine, swine or vegetable origin and available as gauze, sponges, sheets, powder etc.

·         Gelatin based agents are able to adjust to irregular wound and surgical cavities hence, they are practical in minimally invasive procedures.

·         Cellulose based agents have an antimicrobial activity and can be used for prevention and treatment of surgical site infection.

·         Products are: Surgicel®, FloSeal®, SURGIFLO®, SPONGOSTAN® 

ii.            Adhesives

·         This group constitutes synthetic (cyanoacrylates) and semi-synthetic (glutaraldehyde-albumine) agents

·         They are low viscosity fluids and do not have an intrinsic activity

·         They promote adhesive and sealing properties through a rapid polymerization process in few seconds.

·         Products are: Bioglue®, Glubran®, Omnex®, Coseal® 

 

MRI features associated with hemostatic agents and tissue sealants:

1)    Fibrin sealant:

·         Product: Tachosil®

·         Tachosil® is a topical fibrin sealant patch consisting of human fibrinogen and human thrombin coated onto an equine collagen sponge

·         It is used as a surgical patch over the bleeding area

·         These agents are absorbable and do not form a mass, therefore they are not clearly seen on MRI after PN. However, sometimes a linear area at the operation site without contrast enhancement may be seen ( Fig. 2 ).

2)    Cellulose based agents [regenerated oxidized cellulose (ROC)]:

·         Product: Surgicel®

·         ROC is an absorbable hemostatic agent and found in layers that can be adapted to irregular surfaces and inaccessible areas [4]

·         They are vegetable-derived products, biodegradable and biocompatible.

·         They are placed as a rolled bolster in the parenchymal defect site following the excision of the tumor [1]. They achieve approximation and local compression at the resection site.

·         When cellulose is exposed to blood, it becomes engorged and forms a gelatinous mass [5].

·         In vitro, a peripheral T2 hypointense, T1 hyperintense rim was seen around Surgicel® at the third month ( Fig. 3 ).

·         These agents may be seen as mass like lesion in MRI after the operation (bolster-related mass) ( Fig. 4 ).

·         Bolsters of bioabsorbable agents can induce foreign body reactions and form granulomas, mimicking residual tumor.

·         Bolster-related mass may demonstrate linear restricted diffusion areas in it and mild delayed peripheral enhancement. They are usually circumscribed with a T2 hypointense thick line resembling a fibrous capsule.

·         The clue to differentiate it from tumor recurrence is decrease in size in sequential imaging methods and the awareness of the placement of the hemostatic agent ( Fig. 5 ).

·         The bolster-related mass regresses gradually in months 

3)    Gelatin based sponge:

·          Product: Spongostan®

·         They provide a mechanical matrix that promotes clotting

·         Spongostan® is available in different sponge forms

·         It is a thicker material than Surgicel®

·         Rare cases of abscess or granuloma formation have been reported with the use of gelatin-based hemostatics.

·         In vitro, Spongostan® covered with blood shows low T2 signal and high T1 signal intensity at the third month. It does not show diffusion restriction. ( Fig. 6 ).

·         These agents may be seen as mass like lesion in control MRI (bolster-related mass) ( Fig. 7 ).

·         Bolster-related mass may demonstrate linear restricted diffusion areas in it and mild delayed peripheral enhancement. They are usually circumscribed with a T2 hypointense thick line resembling a fibrous capsule.

 

4)    Adhesives:

·         Product: Bioglue®

·         These agents are dispensed by a controlled delivery system

·         Upon application to the tissue at the repair site, they create a flexible mechanical seal independent of the body’s clotting mechanism

·         They may be used in conjunction with other hemostatic agents

·         In vitro, Bioglue® covered with blood may show low T2 signal intensity at the second week however, it could not be differentiated clearly at the third month. It does not show diffusion restriction. ( Fig. 8 ).

·         They are not readily seen in control MRI’s of the patients since they do not form a mass ( Fig. 9 )

5)    Hemostatic powder:

·         Product: Bloodcare powder®

·         It is an efficient hemostat based on hydrogen calcium salt of oxidized cellulose.

·         These absorbable hemostatic particles are indicated on the bleeding surface of a wound as an adjunctive hemostatic device to assist when control of bleeding by pressure, ligature and other conventional procedures is ineffective or impractical.

·         These particles, with its granular molecules rapidly absorbing the moisture from the blood, gather the visible component (platelets, red blood cells, albumin, thrombin, fibrin, etc.) in the blood.

·         In vitro, hemostatic powder covered with blood may show mild T2 low signal intensity at the second week which becomes more prominent at the third month. T1 signal drops by the time. ( Fig. 10 ).

·         In MRI’s groups of these particles may be seen as hypointense dots in T1-weighted images, particularly in T1-weighted in-phase gradient echo sequence in which susceptibility is clearly seen ( Fig. 11 ).

Other materials that have role in hemostasis

1)    Autologous perirenal fat

·         In some cases, perinephric fat may be packed into the surgical bed to help achieve hemostasis.

·         The fatty packing material may be mistaken for a fatty mass, such as an angiomyolipoma, in control imaging studies if the surgery history is not known.

·         Autologous fat package is easily recognized at the defect site after PN due to classical fat signal. A fibrous capsule surrounding fat package or peripheral contrast enhancement may be seen ( Fig. 12 ).

·         It is not absorbed, seems same in the sequential follow-up.   

2)    Hemo clips

·         It is a permanent, non-absorbable polymer clip that is used in surgery in order to achieve hemostasis by tissue approximation or vessel closure ( Fig. 13 ).

·         Due to its non-conductive nature, it is considered MRI safe.

·         These clips retain stable in time, however they are not readily seen or differentiated from granulation tissues in MR images.

Other materials that have role in suture support

1)    PTFE pledgets

·         These are non absorbable pledgets composed of polytetrafluoroethylene (PTFE) / Teflon.

·         Product: PLEDGETS®

·         When there is possibility of tearing of sutures through tissue, PTFE pledgets can be used as nonabsorbable suture support. This is particularly important in partial nephrectomy since sutures may tear renal parenchyma.

·         They cause minimal inflammatory reaction, followed by gradual encapsulation by fibrous connective tissue.

·         In vitro, PTFE pledgets may show T2 and T1 low signal intensity at the early phase after the operation however they could not be differentiated at the third month study ( Fig. 14 ).

·         In imaging, they are not seen or differentiated from granulation tissues..

Take home notes:

·         Fibrin sealants and adhesives usually do not form masses; therefore they are not seen in control MRI images after PN.

·         Cellulose-based agents and gelatin-based sponges may form a bolster-like mass in the parenchymal defect site and this mass regresses gradually.

·         T2 hypointense rim is an important finding to diagnose bolster-related mass

·         Linear diffusion restriction areas may be seen inside the bolster-related mass, however in case of nodular diffusion restriction, recurrent tumor should be considered.

·         Hemostatic powder may be seen as T1 hypointense dots.

·         The fatty packing material may imitate a fatty mass, (e.g. angiomyolipoma), therefore knowledge of surgery history is important.

Hemo clips and PTFE pledgets are not readily seen or differentiated from granulation tissues in MR images

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