Ultrasound in pulmonary CHD:

The lung is the second most common site (18 –35%) [1,2 ].The incidence of concomitant liver and lung hydatidosis  varies from 5.8 –13.3 % [3, 4 ]. Most CE cases are diagnosed by a combination of clinical findings, medical imaging and serological tests. In 1996 we have introduced the wall sign (WS) as an ultrasound feature of CE, which has proven to be pathognomonic [5,6,7,8,9]
Because of the limited ultrasound access to the ventilated lung within the rib cage,reducing the visibility of intrapulmonary processes, pulmonary CE has always represented a challenge to ultrasound examinations. In this study, we have investigated suspected cases of pulmonary hydatid disease, utilizing the ultrasound WSC.

Discussion
Conventional chest radiography has been the diagnostic main stay in patients with CE of the lungs. Often coupled with serological tests; It is common for the diagnosis to be made from the microscopic discovery of hooklets in espiratory secretion, highlighting the value of close cooperation with microbiological staffs.Serologic tests including latex agglutination and specific IgE, IgM and IgG ELISA, are not standardised. IgG ELISA, however, has been shown to be the most sensitive test in pulmonary echinococcosis, with an 83% sensitivity [11]. IgG ELISA also seems to be useful for postoperative follow-up because persistently elevated antibody titres in the first year following surgery or a titre increase following a progressive decrease reliably indicates relapse or re-infection [11].
Bronchoscopy is indicated upon suspicion as it was shown to be useful in diagnosis of pulmonary hyadatid disease,and revealed pathological findings in 70%. CT scans are helpful in determining the exact anatomical location of the ulmonary cystic lesions, but there were no pathognomonic features for CE [12] on CT. Several conditions, such as bronchogenic carcinomas, benign tumours,inflammatory cystic masses,metastasis,and solid or fluid-filled cysts may mimic echinococcal cysts and make a definitive diagnosis difficult, even when using a multimodality imaging approach.Therefore, any hyperdense mass displayed on plain x-ray may represent a diagnostic pitfall regarding CE.
Following meticulous observation of the ultrasound scan of CE in different anatomical locations,we introduced the WS [5 –10].In this study, the WS was clearly displayed in all multivesicular cysts, because the cystic fluid filling the daughter cysts functions as a good acoustic window and makes it easier to see the adjacent walls. Interestingly, CT scan failed to identify any cystic lesion in 9 cases because of massive pleural effusion in which the cysts were immersed, while, for exactly the same reason (acoustic window), ultrasound examination of the same patients demonstrated the cysts very clearly. The diagnostic uncertainty of ultrasound in some cysts of the unilocular type can be attributed to multiple factors, such as continuing respiratory movement and deeply seated cysts where aerated lung tissue acts as a barrier for the ultrasound beam.
Our studies; conducted on pulmonary echinococcosis supports the search for the WS in pulmonary CE and shows that ultrasound greatly facilitates clinical decision making. In addition, the application of the WS in conjunction with plain x-ray may reduce the need for CT, which is not available in all hospitals. CT scan, however, is useful for determining the exact anatomical position of the cyst, even without using CT contrast agents.

References
1 Shields TW.General Thoracic Surgery.Willams &Wilkins,1994; Fourth Edition;Volume II:1021 –1027
2 Safioleas M,Misiakos EP,Dosios T et al.Surgical treatment for lung hydatid disease.World J Surg 1999;23:1181 –1185
3 Saidi F.Surgery of hydatid disease.WB Saunders,Philadelphia 1976; 3:31 –155
4 Kidess EA,Akiel AS,Ba ’aqeel HS et al.Echinoccosis:an obstetric and gynecologic view.Ann Saudi Med 1988;8:202 –207
5- El Fortia M,Bendaoud M,Shaban A et al.Noveau critere pour l ’identification du kyste hydatique non-complique,le signe de la paroi.J Echgr Med 1996;17:30 –35
6- El Fortia M, Bendaoud M, Badi H et al. Giant Hydronephrosis Mimicking Echinococcal Cyst. Ultraschall in Med in press
7- El Fortia M,Bendaoud M,Maghur H et al.Intracavitary cardiac hydatid cyst and the wall sign criteria.European Journal of Ultrasound 1998; 8:115 –117
8- El Fortia M,Bendaoud M,Yhia A.Subcutaneous extension of a large Echinococcal cyst.Eur Radiolo 2000;10:870
9- El Fortia M,Bendaoud M,Eldurrega S.Primary uterine hydatid cyst and the wall sign criteria.Ultrasound in obstetric and gynecology 1999; 13:374
10- El Fortia M, Elhajaji E, Elmadani B et al. Are they Spherules of Ovarian Cystic Teratoma or Daughter Cysts of
11-  Zarzosa M P, Orduna Domingo A, Gutierrez P et al. Evaluation of six serological tests in diagnosis and postoperative control of pulmonary hydatid disease patients. Diagn Microbiol Infect Dis 1999;35 (4):255 – 262
12- Zapatero J, Madrigal L, Lago J et al. Surgical treatment of thoracic hydatidosis:a review of 100 cases.Eur J Cardiothorac Surg 1989; 3:436 – 440 1986;10:226 –232

The WSC in Intact Hydatid cysts

Infection cycle

Like many other parasite infections, the course of Echinococcus infection is complex. The worm has a life cycle that requires definitive hosts and intermediate hosts. Definitive hosts are normally carnivores such as dogs, while intermediate hosts are usually herbivores such as sheep and cattle. Humans also function as intermediate hosts, although they are usually a 'dead end' for the parasitic infection cycle.

The disease cycle begins with an adult tapeworm infecting the intestinal tract of the definitive host. The adult tapeworm then produces eggs which are expelled in the host's feces. Intermediate hosts become infected by ingesting the eggs of the parasite. Inside the intermediate host, the eggs hatch and release tiny hooked embryos which travel in the bloodstream, eventually lodging in an organ such as the liver, lungs and/or kidneys. There, they develop into hydatid cysts. Inside these cysts grow thousands of tapeworm larvae, the next stage in the life cycle of the parasite. When the intermediate host is predated or scavenged by the definitive host, the larvae are eaten and develop into adult tapeworms, and the infection cycle restarts.

Disease symptoms

As already noted, Echinococcus infection causes large cysts to develop in intermediate hosts. Disease symptoms arise as the cysts grow bigger and start eroding and/or putting pressure on blood vessels and organs. Large cysts can also cause shock if they happen to rupture.

About Us

This site is by authors of the “CYSTIC HYDATID DISEASE”  and authors have done the ultrasound  diagnosis of largest series of hydatid disease. Authors are popular radiologists otherwise and offer their opinion on the ultrasound images of suspected hydatid disease, with their diverse experience of the rarest of rare locations and appearances for the hydatid cyst would be able to help you. Mail us elfortia@doctor.com

History Of Hydatid Disease

Hydatid disease is one of the oldest diseases known to man. It was first described in the Talmud as a "Bladder full of water" [1-2]. Hippocrates described the human Echinococcus disease more than two thousand year ago with a very interesting expression (liver filled with water) [3]. Al-Rahzes, subsequently wrote detailed script on hydatid cyst of the liver about one thousand years ago [4]. However, the exact life cycle of the parasite was only recognized in 1928 by Dew et al. [1-2].

The WSC in Intact Hydatid cysts

a) Unilocular Hydatid cyst:

Conventional Ultrasound utilizing the pathgnomonic WSC (El Fortia Criteria) is superior in identifying Hydatid cysts among other non-hydatic in nature [1-6]. The WSC (Fig. 4 a-c & 5 a-c & 6 a-b)  which was simply applied by showing the pericystic reaction in the organ tissue and the ectocyt as a double layered wall. It is based on magnification of the cyst wall at the cyst / organ interface indicating double layers in case of the unilocular cysts and their internal septa in case of multilocular cysts.

 

If the adventitia was not or faintly seen we should search for a sonolucent rim at the site of interface between the organ tissue and cyst. This rim represents a slit of viscus fluid which is sonographiocally considered as an indirect sign for the existence of adventitia. In this patient seen in ( Fig 6a), the huge cyst was  attached to a small area of the host' organ  (about 2 cm attached area) which does not permit to the host organ to react against cyst strongly, therefore the adventitia was seen very faint.
But also in the case of ( Fig 6b), the adventitia can not be visualized although the cyst is embedded into the liver tissue,  most probably was due to decreased immunity of the patient.

Intrabiliary rupture of hydatid cyst-MRCP

Hydatid cysts of the liver exert pressure on the surrounding parenchyma, and in approximately one-fourth of the cases, due to higher pressure in the cyst, the cysts eventually leak into small bile ducts or perforate into large ones. Thus the most common complication of hydatid cyst of the liver is spontaneous rupture into the biliary tract. Intrabiliary rupture occurs into the right duct in 55–60% of cases, into the left duct in 25–30% and rarely into the confluence or gall bladder.

This is a case of a hydatid cyst of the left lobe with MRCP images which ruptured spontaneously into the left hepatic duct. Thick slab and Thin Slab images are shown, with communication with hydatid cyst and left hepatic duct and intraluminal linear filling defects.