User login
MADISON, WISC. – said Robert Lambert, MD, speaking at the annual meeting of the Spondyloarthritis Research and Treatment Network (SPARTAN).
“Low-dose CT of the SI [sacroiliac] joints is probably underutilized,” said Dr. Lambert, chair of the department of radiology and diagnostic imaging at the University of Alberta, Edmonton. “Subtle bony changes are demonstrated very well, and it can be an excellent test for resolving equivocal findings on x-ray or MRI.”
An important first step in making imaging decisions is to put concerns about radiation exposure in context, said Dr. Lambert. “Today, almost all CT effective exposure doses are considered low risk.”
Older studies have shown that a conventional two-view chest radiograph delivers a dose of 0.1 mSv – the equivalent of 10 days of background radiation – whereas the highest radiation dose is delivered by a CT scan of the abdomen and pelvis with and without contrast. This examination delivers an effective dose of 20 mSv, the equivalent of 7 years of background radiation. Dr. Lambert pointed out what the “moderate” additional lifetime risk of malignancy – 1:500 – associated with this scan looks like in real-world numbers: “So the lifetime risk of cancer would increase from 20% to 20.2%.”
Recently, measurements of effective doses delivered in low-dose CT (ldCT) have shown that “most doses are significantly lower than previously quoted,” said Dr. Lambert. For example, ldCT of the SI joints delivers just 0.42 mSv, a radiation dose that’s in the same minimal risk category as a chest radiograph. In fact, for patients with high body mass, the radiation dose from ldCT of the SI joints can be less than that from a conventional radiograph.
“Could low-dose CT of the spine better detect new bone formation, compared to x-ray?” Dr. Lambert asked. A recent study attempted to answer the question, looking at 40 patients with ankylosing spondylitis who received ldCT at baseline and 2 years later (Ann Rheum Dis. 2018;77:371-7). In developing a CT syndesmophyte score (CTSS), two independent readers, blinded to the time order in which images were obtained, assessed vertebral syndesmophytes in the coronal and sagittal planes for each patient. The conclusion was that “new bone formation in the spine of patients with ankylosing spondylitis can be assessed reliably,” Dr. Lambert said.
A related study directly compared the new CTSS system with the modified Stoke Ankylosing Spondylitis Spine Score, used for conventional radiographs. Both studies used data from the Sensitive Imaging in Ankylosing Spondylitis cohort.
In this latter study, whole spine ldCT tracked progression better than conventional radiographs because it detected more new and growing syndesmophytes, Dr. Lambert said. One important reason for this was that conventional radiography only has utility in the cervical and lumbar spine and the pelvis, while most progression was seen in the thoracic spine with ldCT (Ann Rheum Dis. 2018;77:293-9).
The radiation dose for ldCT of the spine – approximately 4 mSv – is about 10 times that for ldCT of the SI joints, but still one-half to three-quarters of the dose for a whole-spine CT, Dr. Lambert said. Put another way, the ldCT whole-spine dose is nearly equivalent to the dose for the three radiographic studies required to image the cervical, thoracic, and lumbar spine.
Another imaging approach using CT zooms in on the thoracolumbar spine, imaging vertebrae T10-L4. Through sophisticated computational reconstruction techniques, the researchers were able to quantify syndesmophyte height circumferentially around each vertebra (J Rheumatol. 2015;42[3]:472-8).
The study, which imaged 33 patients at baseline and then at year 1 and year 2, found that the circumferential syndesmophyte height correlated well with spinal flexibility. Variation was low between two scans performed on the same day, at 0.893% per patient. Despite these advantages of high reliability and good sensitivity to change, one consideration for clinical consideration is the radiation dose, estimated about 8 mSv, Dr. Lambert noted.
Though MRI is a keystone for diagnosis and management of spondyloarthritis, Dr. Lambert pointed out that it’s more expensive than CT and still not routinely available everywhere. He also noted that reimbursement and prior authorizations may be easier to obtain for CT.
“Low-dose CT has tremendous research potential, especially in the thoracic spine,” said Dr. Lambert. “But it’s not ready for routine clinical use. First, the dose is not trivial, at about 4 mSv.” Also, it’s time consuming to interpret and not all CT scanners are compatible with ldCT techniques. “Lower dose can mean lower imaging quality,” and syndesmophytes can be harder to detect in larger individuals.
Dr. Lambert reported no relevant conflicts of interest.
MADISON, WISC. – said Robert Lambert, MD, speaking at the annual meeting of the Spondyloarthritis Research and Treatment Network (SPARTAN).
“Low-dose CT of the SI [sacroiliac] joints is probably underutilized,” said Dr. Lambert, chair of the department of radiology and diagnostic imaging at the University of Alberta, Edmonton. “Subtle bony changes are demonstrated very well, and it can be an excellent test for resolving equivocal findings on x-ray or MRI.”
An important first step in making imaging decisions is to put concerns about radiation exposure in context, said Dr. Lambert. “Today, almost all CT effective exposure doses are considered low risk.”
Older studies have shown that a conventional two-view chest radiograph delivers a dose of 0.1 mSv – the equivalent of 10 days of background radiation – whereas the highest radiation dose is delivered by a CT scan of the abdomen and pelvis with and without contrast. This examination delivers an effective dose of 20 mSv, the equivalent of 7 years of background radiation. Dr. Lambert pointed out what the “moderate” additional lifetime risk of malignancy – 1:500 – associated with this scan looks like in real-world numbers: “So the lifetime risk of cancer would increase from 20% to 20.2%.”
Recently, measurements of effective doses delivered in low-dose CT (ldCT) have shown that “most doses are significantly lower than previously quoted,” said Dr. Lambert. For example, ldCT of the SI joints delivers just 0.42 mSv, a radiation dose that’s in the same minimal risk category as a chest radiograph. In fact, for patients with high body mass, the radiation dose from ldCT of the SI joints can be less than that from a conventional radiograph.
“Could low-dose CT of the spine better detect new bone formation, compared to x-ray?” Dr. Lambert asked. A recent study attempted to answer the question, looking at 40 patients with ankylosing spondylitis who received ldCT at baseline and 2 years later (Ann Rheum Dis. 2018;77:371-7). In developing a CT syndesmophyte score (CTSS), two independent readers, blinded to the time order in which images were obtained, assessed vertebral syndesmophytes in the coronal and sagittal planes for each patient. The conclusion was that “new bone formation in the spine of patients with ankylosing spondylitis can be assessed reliably,” Dr. Lambert said.
A related study directly compared the new CTSS system with the modified Stoke Ankylosing Spondylitis Spine Score, used for conventional radiographs. Both studies used data from the Sensitive Imaging in Ankylosing Spondylitis cohort.
In this latter study, whole spine ldCT tracked progression better than conventional radiographs because it detected more new and growing syndesmophytes, Dr. Lambert said. One important reason for this was that conventional radiography only has utility in the cervical and lumbar spine and the pelvis, while most progression was seen in the thoracic spine with ldCT (Ann Rheum Dis. 2018;77:293-9).
The radiation dose for ldCT of the spine – approximately 4 mSv – is about 10 times that for ldCT of the SI joints, but still one-half to three-quarters of the dose for a whole-spine CT, Dr. Lambert said. Put another way, the ldCT whole-spine dose is nearly equivalent to the dose for the three radiographic studies required to image the cervical, thoracic, and lumbar spine.
Another imaging approach using CT zooms in on the thoracolumbar spine, imaging vertebrae T10-L4. Through sophisticated computational reconstruction techniques, the researchers were able to quantify syndesmophyte height circumferentially around each vertebra (J Rheumatol. 2015;42[3]:472-8).
The study, which imaged 33 patients at baseline and then at year 1 and year 2, found that the circumferential syndesmophyte height correlated well with spinal flexibility. Variation was low between two scans performed on the same day, at 0.893% per patient. Despite these advantages of high reliability and good sensitivity to change, one consideration for clinical consideration is the radiation dose, estimated about 8 mSv, Dr. Lambert noted.
Though MRI is a keystone for diagnosis and management of spondyloarthritis, Dr. Lambert pointed out that it’s more expensive than CT and still not routinely available everywhere. He also noted that reimbursement and prior authorizations may be easier to obtain for CT.
“Low-dose CT has tremendous research potential, especially in the thoracic spine,” said Dr. Lambert. “But it’s not ready for routine clinical use. First, the dose is not trivial, at about 4 mSv.” Also, it’s time consuming to interpret and not all CT scanners are compatible with ldCT techniques. “Lower dose can mean lower imaging quality,” and syndesmophytes can be harder to detect in larger individuals.
Dr. Lambert reported no relevant conflicts of interest.
MADISON, WISC. – said Robert Lambert, MD, speaking at the annual meeting of the Spondyloarthritis Research and Treatment Network (SPARTAN).
“Low-dose CT of the SI [sacroiliac] joints is probably underutilized,” said Dr. Lambert, chair of the department of radiology and diagnostic imaging at the University of Alberta, Edmonton. “Subtle bony changes are demonstrated very well, and it can be an excellent test for resolving equivocal findings on x-ray or MRI.”
An important first step in making imaging decisions is to put concerns about radiation exposure in context, said Dr. Lambert. “Today, almost all CT effective exposure doses are considered low risk.”
Older studies have shown that a conventional two-view chest radiograph delivers a dose of 0.1 mSv – the equivalent of 10 days of background radiation – whereas the highest radiation dose is delivered by a CT scan of the abdomen and pelvis with and without contrast. This examination delivers an effective dose of 20 mSv, the equivalent of 7 years of background radiation. Dr. Lambert pointed out what the “moderate” additional lifetime risk of malignancy – 1:500 – associated with this scan looks like in real-world numbers: “So the lifetime risk of cancer would increase from 20% to 20.2%.”
Recently, measurements of effective doses delivered in low-dose CT (ldCT) have shown that “most doses are significantly lower than previously quoted,” said Dr. Lambert. For example, ldCT of the SI joints delivers just 0.42 mSv, a radiation dose that’s in the same minimal risk category as a chest radiograph. In fact, for patients with high body mass, the radiation dose from ldCT of the SI joints can be less than that from a conventional radiograph.
“Could low-dose CT of the spine better detect new bone formation, compared to x-ray?” Dr. Lambert asked. A recent study attempted to answer the question, looking at 40 patients with ankylosing spondylitis who received ldCT at baseline and 2 years later (Ann Rheum Dis. 2018;77:371-7). In developing a CT syndesmophyte score (CTSS), two independent readers, blinded to the time order in which images were obtained, assessed vertebral syndesmophytes in the coronal and sagittal planes for each patient. The conclusion was that “new bone formation in the spine of patients with ankylosing spondylitis can be assessed reliably,” Dr. Lambert said.
A related study directly compared the new CTSS system with the modified Stoke Ankylosing Spondylitis Spine Score, used for conventional radiographs. Both studies used data from the Sensitive Imaging in Ankylosing Spondylitis cohort.
In this latter study, whole spine ldCT tracked progression better than conventional radiographs because it detected more new and growing syndesmophytes, Dr. Lambert said. One important reason for this was that conventional radiography only has utility in the cervical and lumbar spine and the pelvis, while most progression was seen in the thoracic spine with ldCT (Ann Rheum Dis. 2018;77:293-9).
The radiation dose for ldCT of the spine – approximately 4 mSv – is about 10 times that for ldCT of the SI joints, but still one-half to three-quarters of the dose for a whole-spine CT, Dr. Lambert said. Put another way, the ldCT whole-spine dose is nearly equivalent to the dose for the three radiographic studies required to image the cervical, thoracic, and lumbar spine.
Another imaging approach using CT zooms in on the thoracolumbar spine, imaging vertebrae T10-L4. Through sophisticated computational reconstruction techniques, the researchers were able to quantify syndesmophyte height circumferentially around each vertebra (J Rheumatol. 2015;42[3]:472-8).
The study, which imaged 33 patients at baseline and then at year 1 and year 2, found that the circumferential syndesmophyte height correlated well with spinal flexibility. Variation was low between two scans performed on the same day, at 0.893% per patient. Despite these advantages of high reliability and good sensitivity to change, one consideration for clinical consideration is the radiation dose, estimated about 8 mSv, Dr. Lambert noted.
Though MRI is a keystone for diagnosis and management of spondyloarthritis, Dr. Lambert pointed out that it’s more expensive than CT and still not routinely available everywhere. He also noted that reimbursement and prior authorizations may be easier to obtain for CT.
“Low-dose CT has tremendous research potential, especially in the thoracic spine,” said Dr. Lambert. “But it’s not ready for routine clinical use. First, the dose is not trivial, at about 4 mSv.” Also, it’s time consuming to interpret and not all CT scanners are compatible with ldCT techniques. “Lower dose can mean lower imaging quality,” and syndesmophytes can be harder to detect in larger individuals.
Dr. Lambert reported no relevant conflicts of interest.
EXPERT ANALYSIS FROM SPARTAN 2019