Dr. Osman is the Program Director of the Division of
Nuclear Medicine, Department of Radiology, Saint Louis University
Hospital, St. Louis, MO.
Today, more than ever, doctors are transforming patient care through
the early detection and diagnosis of disease, giving patients a greater
chance of survival.
The 5-year relative survival rate for all
cancers diagnosed between 2001 and 2007 is 67%, up from 49% in
1975-1977. More specifically, for detection of breast cancer at the
early localized stage, the 5-year survival rate is 98%,1 for prostate cancer it is 99.6%,2 and for stage 1 lung cancer it is 45% to 49%.3
The improvement in survival reflects both progress in diagnosing
certain cancers at earlier stages and improvements in treatment.4
of this early detection is achieved through medical imaging technology.
One imaging technology that is gaining more widespread use is the
combination of single photon emission computed tomography (SPECT) and
computed tomography (CT). In the nuclear medicine division at Saint
Louis University School of Medicine, Saint Louis, MO, 50% of the
patients referred for a nuclear medicine study receive a SPECT/CT exam.
The majority are scanned for metastatic bone disease, pheochromocytoma,
neuroblastoma, and cardiac imaging, and the remaining for
musculoskeletal, hepatobiliary, renal, and neurological conditions.
the recent installation of the BrightView XCT SPECT/CT system by
Philips Healthcare, doctors at Saint Louis University School of Medicine
are effectively changing patient management, while lowering the
radiation dose in some cases and increasing the speed of image
acquisition and reporting in others.
Clearing technical hurdles
Hybrid SPECT/CT imaging has been instrumental in overcoming some of
the inherent shortcomings of SPECT imaging, in particular the lack of
While SPECT gave us tomographic information and higher sensitivity
than planar, you still had challenges with localization of lesions
because there still wasn’t the detailed anatomy from the CT.
hybrid SPECT/CT systems combine SPECT cameras with conventional
diagnostic CT systems. While these dual-gantry systems resolve the
localization challenges, they also introduce additional complexities of
Although the addition of the CT addressed these
challenges by adding the anatomy and the localization of lesions, it
brought with it its own challenges, including a larger footprint,
increased radiation dose, and more training for the technologists and
physicians. The radiation from the CT was also an important
consideration in pediatric patients.
The unique design of the
BrightView XCT system overcomes many of these obstacles. This hybrid
imaging system integrates a full featured variable angle gamma camera
with a flat-panel cone-beam CT component used for localization and
attenuation correction of the SPECT data. The flat-panel CT component is
mounted on the same rotatable gantry as the SPECT detectors. This
coplanar configuration reduces room size requirements and system weight
compared to hybrid systems using spatially separated SPECT and CT
gantries. Furthermore, it reduces the amount of table translation
required between the SPECT and CT imaging position. The-flat panel
localization images are acquired with a fraction of the dose compared to
a diagnostic CT exam, using less power to operate and without requiring
any additional dose for a scout or topogram image that conventional CT
scanners require. Furthermore, the high-resolution flat panel detector
enables true isotropic voxels, which means that image resolution is
maintained when the data are viewed from any angle. This is particularly
important in the context of SPECT/CT imaging, since SPECT data also
have isotropic voxels and are routinely reviewed in transverse, sagittal
and coronal views.
A costly problem for hospitals when acquiring
a new system is retrofitting an existing floor plan, which can be
prohibitively expensive. However, BrightView XCT’s footprint is compact
and fits into rooms as small as 15´ 6˝ × 11´ 7˝ (4.72 meters × 3.53
meters) with minimal shielding, and, in most cases, there is no need to
The BrightView XCT was a solution that made
everyone happy—the hospital and physicians. It gave us the same
footprint as the dedicated SPECT camera, so we didn’t have to build out a
larger room. Since the system was designed entirely for nuclear
medicine, the learning curve on the technology was not as steep as with
other SPECT/CT scanners, and training the staff did not pose any
significant concerns. We were able to overcome a lot of the limitations
of SPECT/CT when we installed the BrightView XCT, and we promoted this
fact to our referral network.
Hybrid imaging technology will
become the gold standard for conventional scintigraphy for a number of
oncology applications, including bone imaging for staging malignancy,
tumor scintigraphies that visualize neoplastic foci via tumor-specific
agents, such as octreotide labeled with 111-In or 131-I, and sentinel
lymph node scintigraphy, where SPECT/CT fusion helps considerably in
localizing the first lymph node draining a tumor.5
the localization of SPECT uptake that CT provides, physicians are
better able to identify uptake as pathological versus normal
physiological uptake. In a recent study, researchers investigated the
added value of SPECT/CT for correlation of MIBG scintigraphy (planar and
SPECT) and diagnostic CT in neuroblastoma and pheochromocytoma. In the
small series of cases examined, the improved anatomical localization
provided by SPECT/CT increased the diagnostic certainty in 89% of
A recently published study
evaluated Sentinal Lymph Node Excision (SLNE) with and without SPECT/CT.
The study concluded that the use of SPECT/CT was associated with a
higher rate of metastatic node detection, which subsequently prolonged
the disease-free survival. The same study showed that the use of
SPECT/CT changed the surgical approach for SLNE in 33/149 (22.1%)
Clinical advantages in musculoskeletal imaging
Concurrent imaging and the ability to acquire high-resolution CT
images are two features of BrightView XCT that have helped to stimulate a
renewed interest in musculoskeletal (MSK) imaging. Concurrent imaging,
which allows the user to create multiple datasets from a single
acquisition step, offers more flexibility in acquisition protocols and
provides additional information without requiring additional imaging
time. One way to make use of concurrent imaging is in dual isotope
A classic example is with infection imaging in the
musculoskeletal system, and with one day for the indium and one day for
the bone scan. Now we can do a simultaneous acquisition for the indium
and the bone scan without worrying about patient repositioning or
additional image acquisitions in a single day. That is a very unique
feature that is available now on the XCT.
imaging capabilities of the BrightView XCT system have also proved
useful for MSK imaging, especially when imaging of the extremities is
involved. The high-resolution acquisition on the new system has come in
handy by giving us a niche in musculoskeletal imaging. The MSK
applications brought life to bone scanning. We can now produce
information and give our referring physicians images that have a 0.33-mm
resolution of the foot or hand where they suspect a tumor or an
infection. This is compared to studies we had where magnetic resonance
imaging (MRI) and x-rays were negative, the bone scan planar was
negative, and even the SPECT was questionable, until we did the bone
examination at high-resolution image acquisition, which showed the
abnormality with high certainty. This enabled us to provide information
to referring physicians that we would otherwise not be able to do.
a recent case, a 46-year-old female presented with a history of hepatic
adenoma and persistent elevated alkaline phosphatase since October
2011. There had been no history of previous fracture or trauma. A
whole-body planar bone scan (Figure 1) with focal uptake in the left
distal femur indicated the differential diagnosis involved benign and
malignant conditions. The limited uptake of the upper-thigh SPECT/CT
(Figure 2) revealed the uptake to be within the bone marrow. The
differential diagnosis involved benign and malignant lesions. Yet, a
high-resolution SPECT/CT of the left distal femur (Figure 3) showed
stippled calcifications within the distal femoral intramedullary cavity
without additional aggressive features most consistent with an
enchondroma. Given the information already provided by the
high-resolution SPECT/CT examination acquired on the BrightView XCT, the
x-ray (Figure 4) or any additional radiologic evaluation would not be
Patient management has subsequently changed by reducing
the need for follow-up exams, such as MRI, or further evaluation because
we now can provide functional and anatomical information without
additional image acquisition. This not only reduces cost to the
healthcare system and additional cost to the patient, but also speeds up
throughput because there is no lag in time between exam 1 and exam 2.
Clinical advantages in cardiology
The American Society of Nuclear Cardiology and the Society of Nuclear
Medicine have jointly recommended the use of attenuation correction in
addition to ECG gating for SPECT myocardial perfusion studies.8
Attenuation in cardiac studies has always been a challenge, but the
BrightView XCT is well-suited to attenuation correction for cardiac
imaging. The flat-panel CT acquires a low-dose (0.12 mSv) CT image of
the entire heart volume in just one 60-second rotation while the patient
is breathing normally.
In this way, the data used for
attenuation correction is averaged over multiple respiratory cycles to
match the position of the heart during the SPECT acquisition.
XCT also supports the Astonish reconstruction technology, which can
process half-count data without compromising image quality. This gives
the nuclear physician the option of improving laboratory efficiency by
reducing the acquisition time using conventional dosing protocols or
reducing the patient radiation dose by injecting less radioactivity and
using more conventional acquisition times. The ability to take advantage
of the cardiac application has allowed us to reduce the acquisition
time by half or cut the injection by half, depending on the patient
population (Figure 5).
The Astonish reconstruction technology
with attenuation correction can be used to further reduce patient dose
and imaging time by enabling stress-only imaging (Figure 6).
Historically, stress-only imaging has been underutilized, despite
findings that stress-only myocardial perfusion imaging (MPI) saves time
by eliminating rest imaging in some patient populations, which is
important for patient throughput.9
If you do
stress-only, you can get the answer in <1 hour instead of the 4 hours
it typically takes, with one less injection, and reducing the radiation
dose by 30% to 40%. Now with the SPECT/CT, we can do stress-only
images, and if the stress is negative, then we don’t need to do any
rest-only images. If 50% of the studies are negative, then we can take
advantage of stress-only, which helps with faster image acquisition and
faster transfer of information to the referring physician, as well as
decreasing the radiation dose to the patient.
In many cases,
cardiologists need a quick answer because they are contemplating taking
the patient to the cardiac cath lab. The half-time acquisition with the
stress-only imaging is critical because it provides the information at a
much faster rate and has the potential to significantly improve
operational efficiency without sacrificing accuracy because of the CT
The hospital’s referring physicians
acknowledged the improvement in cardiovascular studies, and the half
dose is especially beneficial in pediatric patients who, by definition,
are more sensitive to exposure to radiation. The referring physicians
are happy that we are scanning them at faster speeds or half the
radiation dose to the patient.
Patient comfort for quality imaging
Another important consideration is patient comfort, especially on
SPECT/CT, where patients spend significantly longer times compared to
dedicated CT or x-ray. The more comfortable the patient, the less
movement there is likely to be and the fewer image artifacts. This is
hugely important in cardiac imaging, where motion between the SPECT and
CT image can cause misalignment between the transmission and emission
data, which can lead to artifacts in the attenuation-corrected SPECT
image. Controlling patient movement is also important in oncology, where
accurate alignment of the two image sets is critical for localizing the
SPECT uptake to the anatomy visualized in the CT image. Being able to
position patients reproducibly is also important for patients who may
undergo several exams over the course of their treatment. The exact
positioning of these patients and alignment of lesions over a series of
scans allows the physician to more accurately evaluate the response to
The BrightView XCT is designed with a large gantry
aperture that provides an open patient experience during the CT scans.
This provides additional comfort for all patients, especially those with
a high body-mass index (BMI) or those suffering from claustrophobia.
The 500-lbs (227 kg) capacity of the patient table also facilitates
imaging high BMI patients. The large bore enables us to acquire SPECT/CT
images for patients with high BMI and not have to resort to planar
Transforming the future of care
Advances in BrightView XCT have made significant strides in low-dose,
high-resolution imaging. But it is only the beginning. We foresee
doctors pushing to get more with less radiation and faster scan times.
We also foresee a demand for dual-tracer image acquisition techniques.
were able to overcome a lot of the limitations of SPECT when we
installed the BrightView XCT system, and we anticipate there will be a
push for more types of simultaneous acquisition imaging.
advantages of BrightView XCT include unique features, such as the large
bore for bariatric patients, improved reporting speed and accuracy,
minimal training required for technologists, the small footprint for
ease of installation, and lower overall cost. Yet what is truly
transforming the quality of care is improved image quality, reduced dose
and shorter scan times, which we expect will lead to better overall
- Early detection plan. National Breast Cancer Foundation. http://www.nationalbreastcancer.org/edp/. Accessed August 24, 2012.
- SEER Stat Fact Sheets: Prostate. National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER).
Lung Cancer (Non-Small Cell). American Cancer Society.
Last Revised on February 17, 2012. Accessed August 24, 2012.
- American Cancer Society: Cancer Facts and Figures 2012. Atlanta, Ga: American Cancer Society, 2012. Last accessed January 6, 2012.
- Bockisch A, Freudenberg LS, Schmidt D, et al. Hybrid imaging by SPECT/CT and PET/CT: Proven outcomes in cancer imaging. Semin Nucl Med. 2009;39:276-289.
Rozovsky K, Kolewitz BZ, Krausz Y, et al. Added value of SPECT/CT for
correlation of MIBG scintigraphy and diagnostic CT in neuroblastoma and
pheochromocytoma. AJR Am J Roentgenol. 2008;190:1085-1090.
Stoffels I, Boy C, Pöppel T, Kuhn J, Klötgen K, Dissemond J,
Schadendorf D, Klode J, et al. Association between sentinel lymph node
excision with or without preoperative SPECT/CT and metastatic node
detection and disease-free survival in melanoma. JAMA. 2012;308:1007-1014.
Heller GV, Links J, Bateman TM, et al. American Society of Nuclear
Cardiology and Society of Nuclear Medicine joint position statement:
Attenuation correction of myocardial perfusion SPECT. J Nucl Cardiol. 2004;11:229-230.
- Duvall WL, Wijetung MN, Klein TM. Stress-only Tc-99m myocardial perfusion imaging in an emergency department chest pain unit. J Emerg Med. 2012:42:642-650. Epub 2011 Aug 27.