Mumbai: A 32-year-old man carrying a liquid oxygen cylinder was killed in a central Mumbai hospital when he was yanked into a magnetic resonance imaging (MRI) machine and he inhaled the gas that leaked out of the container, his family and police said.

The victim, Rajesh Maru, had entered Nair Hospital's MRI chamber with a relative who was about to undergo a scan, his family members said.

The MRI machine's magnetic field pulled Maru and the oxygen cylinder into it, trapping his hand in the machine and causing the cylinder to leak and exposing him to an excessive and lethal amount of oxygen, a police officer and the family members said. But a doctor expressed doubts on the cause of the death.

Two senior radiologists said the incident suggests that Maru had entered the room with a metal not allowed inside MRI chambers that contain powerful magnetic fields. "Patients are always asked to remove all metallic objects incompatible with the MRI machine before they enter the MRI chambers," said Bhupendra Ahuja, president of the Indian Radiological and Imaging Association.

Mumbai police have booked three hospital employees and arrested a doctor and a ward boy for culpable homicide not amounting to murder.

The Mumbai patient's family members said they were asked to keep out mobile phone handsets and other metallic objects before the patient entered the room. But, they claimed, the ward boy said the oxygen cylinder could be carried into the room as the MRI machine had not been switched on.

A senior critical care medicine specialist has said he will be "surprised" if it is established that a leak from the oxygen cylinder was behind the death.

Atul Kulkarni, past president of the Indian Society of Critical Care Medicine, said: "I do not know the circumstances of this incident, but exposure to oxygen is extremely unlikely to kill a person."

Oxygen inside the cylinder is pressurised and in liquid form. Even if the cylinder's nozzle had snapped and there was a leak, it will be diluted by the air in the MRI chamber. "If you shut all the doors of a room and open five of six oxygen cylinders, nothing will happen to you - I would be really surprised if the cause of death was oxygen," Kulkarni said.

The victim's brother-in-law Harish Solanki, who said he was an eyewitness to the incident, said his mother had been admitted to the hospital since January 26 for treatment for viral fever.

"Last evening, the doctor told us to get the MRI done, following which Maru and two other family members approached the MRI room," Solanki said.

He said the ward boy asked the family members to remove all metallic objects, including mobile phone handsets, before entering the MRI room, which they did.

Solanki said the ward boy told them that the oxygen cylinder could be carried inside the MRI room despite the objection raised by the patient's family members.

"One of my family members objected, saying the oxygen cylinder should not be allowed inside as it is metallic and can prove dangerous. However, the ward boy told us that the MRI machine was not switched on," he said.

But when Maru and the patient entered the MRI room, the machine was already switched on, Solanki claimed.

"The powerful magnetic field of the machine pulled Maru towards it along with the oxygen cylinder. Maru's hand got trapped in the machine while the opening of the oxygen cylinder snapped. After hearing this commotion, we all rushed inside the room and pulled him out of the machine," Solanki said.

Another relative said a doctor, and an ayah were inside the MRI room at the time of the incident.

"Maru's finger got crushed in the machine. By the time he was pulled out, he had inhaled excessive amount of oxygen which leaked from the cylinder, causing his death on the spot," Solanki said.

The patient was not affected in the incident.

Following the incident, Agripada police registered a case under section 304 (culpable homicide not amounting to murder) of the IPC against Saurav Lanjekar, a doctor, the wardboy, identified as Vitthal, and an ayah.

The Maharashtra government has announced Rs 5 lakh to the kin of the victim.

Announcing the compensation, BJP MLA Mangal Prabhat Lodha said the three employees had been suspended and an inquiry has been initiated against them by the hospital.

Lodha said he had sought assistance and action against the hospital staffers from Maharashtra chief minister Devendra Fadnavis.