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Story of an extraordinary death: How MRI machines work, and can (in rare cases) kill

Two doctors, two staffers at Mumbai’s BYL Nair Hospital have been charged with causing by negligence the death of a man in the hospital’s Radiology unit

Written by Tabassum Barnagarwala | Updated: February 7, 2018 2:20 pm
MRI machines, MRI machine death, MRI machine accident, How MRI machine works?, India news, indian express explained The MRI room has an MRI-compatible tube to supply oxygen to patients who need it. It is unclear why a cylinder was still needed. (Source: Thinkstock photos/Representational)

WHAT HAPPENED

On January 27, Laxmi Solanki, 65, was taken on an iron-steel trolley from the Medical Intensive Care Unit (MICU) to the Magnetic Resonance Imaging (MRI) unit. She was on oxygen support. MICU ward boy Vitthal Chavan, Dr Saurabh Lanjrekar of the Medicine department, and relatives Harish Solanki, Priyanka Solanki, Tribhuvan Solanki, and Rajesh Maru (the deceased, 32) went along.

At the Radiology department, Dr Siddhant Shah and ayah Sunita Surve were present; Radiology ward boy and Radiology technician were not. Family says Laxmi’s iron trolley was wheeled into Zone III — violating procedure (see summary right) — where she was shifted to special MRI trolley, and taken to a room next to the room that has the machine (Zone IV). At the same time, Maru, holding the oxygen cylinder with his left hand, his fingers wrapped around the cylinder’s nozzle, stepped through the door into Zone IV.

The next INSTANT, Maru, still holding the cylinder, flew off his feet “like a missile” and slammed into the gantry of the machine. The cylinder’s nob snapped, and with his upper body lodged halfway inside the machine’s circular hollow, Maru inhaled a rush of oxygen. Pneumothorax followed, a condition in which air (or other gas) fills the space between the lungs and chest wall, and the lungs collapse.

The Machine was switched off, and Chavan, the family, and the doctors pulled Maru out. One of his fingers, stuck between the broken cylinder knob and the gantry’s magnetic wall, was severed. “He had bloated like a balloon,” brother-in-law Harish Solanki said. Maru was declared dead at the Emergency ward.

SCAN

MRI scanners have giant electromagnets with field strengths of between 0.5 tesla and 1.5 tesla (a fridge magnet is about 0.001T; Earth’s magnetic field is 0.00005T). MRI machine at Nair Hospital had a strength of 1.5T — 1,500 times more powerful than a fridge magnet and 30,000X the geomagnetic field. The body is mostly water (hydrogen and oxygen), and when in the massive, stable magnetic field of the scanner, the hydrogen protons get aligned in the same direction. A radiofrequency source is then switched on and off, repeatedly knocking the protons out of line and back into alignment. Receivers pick up radio signals that the protons send out, and by combining these signals, the machine creates a detailed image of the body’s inside.

Sucked in: As soon as Rajesh Maru stepped into Zone IV, he flew off his feet and slammed into the gantry of the machine. (Illustrations: Subrata Dhar)

KEY QUESTIONS

Why was the cylinder taken inside a Zone where metals are not allowed?

The family says that as Laxmi was transferred to the MRI trolley, Chavan told Maru to pick up the cylinder from the MICU trolley and come along. He allegedly assured the family that the machine hadn’t been switched on yet. But Chavan says Maru picked up the cylinder on his own.

But Laxmi needed the oxygen, right?

The MRI room has an MRI-compatible tube to supply oxygen to patients who need it. It is unclear why a cylinder was still needed. Police have said they are waiting for technicians to tell them if the oxygen support was functional then.

How did this accident happen when the machine hadn’t been turned on?

An MRI machine’s magnetic field is on even when it isn’t scanning. A sign on the door shows a magnet inside the triangle that is universally recognised as a symbol of warning, along with the legends “Strong Magnetic Field” and “Magnet is Always On”. The ‘always’ is underlined.

OK, but why wasn’t the magnet switched off immediately afterward?

An emergency button can be used to demagnetise the machine. “But this can be dangerous. The liquid helium that maintains the magnet’s temperature may vaporise, leading to an accident,” a senior radiologist at Nair Hospital said. Instead, doctors chose to turn off the machine before trying to pull Maru out.

Was the machine otherwise all right?

It was a Philips Achieva 1.5T Nova dual gradient scanner. MRI machines normally have a life of 8-9 years. This one was 9 years old. But it was functioning well, according to Radiology department.

Who is to blame for the tragedy, then?

Chavan, the doctors, and ayah Surve have been arrested and charged under IPC Sec 304A (causing death by negligence). Police say the cylinder shouldn’t have been allowed into the MRI room, even if the family had wanted to take it. SOP of stopping iron trolleys in Zone II wasn’t followed. Chavan was not trained to know that the magnetic field is active even when the machine isn’t. Nair Hospital rotates its staff among departments; Radiology doesn’t have permanent staff.

 

CAN THIS HAPPEN AGAIN?

MRI scans have been widely used since the early 80s, and tens of millions of scans are done every year across the world. Deaths like Maru’s are extremely rare. Only one earlier event — a six-year-old boy was killed in the US after an oxygen cannister drawn by the magnet smashed into his skull in 2001 — is well known.

MUMBAI saw a serious accident in November 2014: At the Advanced Centre for Treatment, Research, and Education in Cancer, Navi Mumbai, ward boy Sunil Jadhav had mistakenly brought in an oxygen cylinder. He and the cylinder were pulled in, and they took technician Swami Ramaiah, who was in the way, along. Ramaiah, who was stuck in the machine for 4 hours, temporarily lost sensation waist downward, suffered kidney damage and urinary bladder puncture.

THE COMMONEST INJURIES are burns, which can be severe. Loud noises in some older machines can result in hearing loss.

Click on the image to view an enlarged version.

WHAT IS THE SAFETY PROTOCOL?

IN INDIA, diagnostic centres doing radiation tests such as X-ray or CT scan must have Atomic Energy Regulatory Board (AERB) approval, and follow AERB guidelines. But MRI scans involve no radiation, and the guidelines do not apply. Precautions are taken as advised by the machines’ manufacturers.

IN THE UK, there is Ionising Radiation (Medical Exposure) Regulation, 2000. It does not apply to MRI scans. The Royal Australian and New Zealand College of Radiologists has formulated MRI Safety Guidelines. They are not mandatory.

IN BMC HOSPITALS, MRI machines are checked by engineers every three months. BMC has now formed a committee of radiology department heads to look into safety. Pictorial warnings will be made bigger; staff will be sensitised to the risks.

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