SPECT-CT- technology of the future
SPECT or single photon emission computed tomography is an integrated part of all
latest gamma cameras and is done in most of the Nuclear Medicine Departments world
wide.
Hybrid imaging techniques (SPECT/CT) enable the fusion of anatomic and functional
data without any scope for misregistration.
With the availability of integrated SPECT/CT scanners, lesions visualized by functional
imaging (gamma camera) can be superimposed on the corresponding anatomic structure
to obtain valuable morphologic information as well.This increases the sensitivity
and specificity of scintigraphic findings and makes the nuclear medicine reports
truly complete.
CT data can also be used for attenuation correction, thus increasing the target
to background ratio of lesions and enabling quantification of uptakes.
Applications of SPECT-CT in clinical practice:
- For sentinel lymph node (SLN) mapping
A combination of lymphoscintigraphy before surgery and mapping with blue dye during
surgery has been demonstrated to be a practicable approach for accurately localizing
the sentinel lymph node. Inguinal and lower axillary lymph nodes can be reliably
detected on planar scans, however, a CT co-registration would be a valuable tool
for sentinel lymph node detection in the pelvis, mediastinum and head and neck region.
This may improve the SLN identification and localization during surgery.
- In malignant skeletal diseases:
- The lesions identified in planar bone scans can be differentiated in to benign and
malignant lesions especially when the lesions are solitary or are cold spots.
- The fused images can be used to guide bone biopsies.
- Benign skeletal lesions can be further characterized by fusion imaging in a single
examination.
- Integrated SPECT/CT images were found to be superior to side by side reading of
SPECT and CT images.
- In Iodine-131 whole body scans in differentiated cancer thyroid cases:
It can help distinguish lymph node metastasis from residual thyroid tissue, lung
metastasis from mediastinum metastasis. Additional information regarding spinal
cord compression, pathological fracture etc. can be obtained in a single study.
- In parathyroid adenomas
Precise anatomic localization of parathyroid adenomas detected on Tc-99m MIBI dual
phase scans enables minimally invasive surgeries for excision of the adenoma.
This is especially useful in patients with distorted neck anatomy or ectopic location
of the gland.
- In adrenocortical tumours and neuroendocrine tumours.
Scintigraphic studies offer high specificity in the diagnosis of above mentioned
condition especially in differentiating residual tumour tissue from scar.However,
the morphologic data obtained with CT/MRI is highly sensitive in diagnosing these
conditions.
Fusion imaging combines the best of both modalities for the diagnosis and characterisation
of these lesions.
- Cardiac imaging
No homogenous photon attenuation in the thorax is one of the most notable limitations
of myocardial perfusions imaging.
Breast attenuation and diaphragmatic attenuation produce artifacts in the anterior/
anteroseptal region and inferior wall leading to false positive findings. These
limitations are overcome by the application of CT based attenuation correction.
Apart from this, the myocardial perfusion SPECT images can be combined with CT based
calcium scoring / CT based coronary angiography to give a complete report. This
option is highly attractive, due to improved logistics, diagnosis and illustrative
visualization.
The advent of SPECT-CT can be considered to mark the journey from “
UNCLEAR” MEDICINE
TO “NEW CLEAR” MEDICINE. For further information and appointment,
Dr.Shefali Gokhale
Consultant
Dept. of Nuclear Medicine
Inlaks and Budhrani Hospital
M.N.Budhrani Cancer Institute
Pune-411001
Back Top