A brief history of Cardiotom™

A brief history of Cardiotom In traditional computer tomography (CT, SPECT, PET) the projections used for image reconstruction are obtained from directions normal to an axis of rotation.

Professor Paul Edholm showed in 1980 that it was possible to perform tomographic imaging from projections obtained at oblique angles, i.e. that it was not necessary for the imaging system to circumvent the imaged object. He called this method Ectomography or limited view angle tomography.

In the beginning of the nineties Dianna Bone, Lars-Åke Brodin and Håkan Elmqvist met to discuss if something could be done about the infrequent use of SPECT for acute bedside diagnosis of ischemic hearth disease. They recognized that one major problem was the bulkiness and immobility of SPECT systems. During the discussion the idea of Ectomography was introduced and they realised that an ectomographic system optimised for cardiac imaging could be made small and mobile. Ectomography further promised the advantages of higher sensitivity and faster imaging especially for small organs such as the heart.

They decided to develop a promising concept into a clinical system, Cardiotom. After some preliminary experiments at the Karolinska Hospital where a hand manoeuvred slant hole collimator was mounted on a gamma camera Cardiotom Mark I was built from a used fork lift and a discarded General Electric gamma camera.

The rather massive (700 kg) Cardiotom Mark I with a long umbilical cord to the Digital Equipment PDP-11 reconstruction computer was used for more than 200 successful patient studies and constituted a clear proof of concept. It was therefore decided to build a more practical system; Mark II was born. Mark II, designed by Tommy Ribbe, used a 40 cm Sopha DS7 detector, a home built pulse analyser and a personal computer. The system weighed less than 300 kg. Image reconstruction was performed with filtered back projection. Two Mark II's were built and deployed at the Karolinska University Hospital and have up till now been used for more than 600 patient studies, most of them acute, many in the cardiac ICCU and some intraoperatively. During this period the clinical usefulness of the system has been demonstrated; it does not require any installation and can be freely moved about from patient to patient or from department to department; it is easy use bedside in the emergency room or in the intensive care unit, the patient remains in bed connected to life support equipment. The resulting images contain the same or better diagnostic information as SPECT images.

The system, however, left some things to be desired; the data acquisition system was not fast or accurate enough, the same applied to the software and reconstruction methods.

New collaborators with expertise in these areas were found in Andras Kerek and Ivan Valastyán physicists from the Royal Institute of Technology, Stockholm; Dezs Novák and József Molnár from ATOMKI, the Institute of Nuclear Research of the Hungarian Academy of Sciences, in Debrecen, Hungary. Now a completely new data acquisition system based on the same technology used in the Eurofighter for radar imaging and a new maximum likelihood reconstruction method were developed together with EKG gated acquisition; all of it neatly wrapped up in new 32-bit software.

The system had now reached a maturity that indicated that it had a commercial potential. The project group, however, neither had the financial muscle; entrepreneurial drive or marketing competence needed for a successful commercialisation. In 2006 collaboration with the successful businessmen Nils-Arne Lindqvist and Mats Hanzon was initiated. They created and financed the company Adolesco AB for the purpose of the commercial development of Cardiotom. Adolesco AB is the owner of all intellectual property associated with Cardiotom and all project members are shareholders in Adolesco.

The so far favourable results from the use of Cardiotom are now being verified by a clinical investigation: Mobile gamma camera in the emergency room as a gate keeper - better care for patients with chest pain at lower cost (SLL20060828). The study is sponsored by the Karolinska University Hospital and the County of Stockholm and is expected to be completed during 2011.

Edholm P, Granlund G, Knutsson H, Peterson C. Ectomopraphy. A new radiographic method for reproducing a selected slice of varying thickness. Acta Radiol 1980;21:433-442.