A scan of Prime Minister Ariel Sharon's brain showed some improvement Thursday, with the remnants of blood from his massive stroke last week having been absorbed, hospital officials said.

As a result, doctors removed a tube they inserted into Sharon's skull to relieve pressure on his brain, the statement from Hadassah Hospital said.

Earlier, Hadassah Hospital said doctors were attaching a new intravenous line into his leg in an effort to prevent infection.

Medical experts, meanwhile, raised new questions about whether blood thinners that Sharon received after a Dec. 18 stroke contributed to last week's massive brain hemorrhage.

Ending the sedation, which has kept Sharon in an induced coma for the past week, is a key step toward assessing the damage from the stroke. Hospital spokesman Ron Krumer said it was unclear when the sedation would be halted.

Sharon, 77, has moved his hands and right leg in response to pain stimuli in recent days, according medical officials. The hospital said he showed slight progress Wednesday, but doctors say it will be days or weeks before a full picture emerges of damage from the Jan. 4 stroke.

"One of the most important stages in the process is opening the eyes," Dr. Jose Cohen, one of Sharon's surgeons, told Israel TV. "Most patients open their eyes within the first three weeks. The sooner they open their eyes, the better. We don't know when he will do it."

The hospital said his heart rhythm was normal.

Hospital officials denied comment on a report in the Maariv daily Thursday that Sharon's medical team as saying his heart began to beat irregularly when doctors tried to scale down the sedatives. The newspaper quoted an unidentified member of Sharon's medical team.

Israeli media have begun to question Sharon's treatment after the mild Dec. 18 stroke.

Doctors prescribed blood thinners after the first stroke, even though the medication raised the risk of hemorrhaging. The hospital disclosed that Sharon suffered from a disease of the brain vessels, cerebral amyloid angiopathy, that could make him particularly susceptible to hemorrhaging.

Dr. Amos Korczyn, head of the neurology department at Tel Aviv University and not involved in his treatment, said doctors should not have prescribed the blood thinners in light of the brain condition.

"It's clear that if someone has a disease that could cause bleeding, giving anticoagulants like this ... is certainly an undesirable situation," he told Army Radio.

But other outside experts said the medical team appeared to have made an appropriate decision. The blood clot that caused the Dec. 18 stroke passed through a small hole in Sharon's heart, and doctors prescribed the medication to prevent a recurrence.

"The blood clot in the heart would be more of a risk than the CAA," said Dr. Nick Lossef, a neurologist at University College Hospital in London.

"These are all very difficult decisions. These are situations where no one really knows what the right thing to do is or what the wrong thing to do is."

Hospital officials defended their treatment. Dr. Yair Birenboim, a senior official at Hadassah, said the blood thinners were prescribed based on a "consensus of experts" that weighed the pros and cons.

"Everyone can be intelligent in hindsight," he told Army Radio on Wednesday.

"This is part of the art of medicine," he added. "We have to consider things from here and there and decrease the damage as much as possible."