The MOC, or Computerized Bone Mineralometry, is a diagnostic test that allows the measurement of calcium and other mineral levels in the bones of the human skeleton.
There are different types of MOCs. The most common type is the MOC DEXA; the MOC DEXA measures the BDM using an X-ray instrument.
The MOC is mainly indicated for: the diagnosis of osteopenia or osteoporosis, the evaluation of the effect of treatments for osteopenia or osteoporosis and the monitoring of all those conditions that can cause osteopenia or secondary osteoporosis.
The MOC does not require special preparation, it lasts between 20 and 30 minutes and does not require any hospitalization.
In general, the results of the MOC are ready 2-3 days after the examination.
What is the MOC?
The MOC is a diagnostic test for measuring calcium and other mineral levels in the bones of the human skeleton.
Through MOC, doctors estimate the so-called bone mineral density ( BDM, from the English Bone Mass Density ).
Bone mineral density is a measure of the quantity of minerals (bone mineral mass) contained in a cubic centimeter of bone (volume).
WHAT DOES OSSEA MINERAL DENSITY INDICATE?
Bone mineral density is an indicator of bone resistance to fractures : BDM values below normal are indicative of a certain bone fragility and a certain susceptibility, on the skeleton's part, to fracture.
WHAT DOES MOC MEAN?
The acronym MOC stands for Computerized Bone Mineralometry .
There are different types of MOCs . Distinguishing each type of MOC is the technique of measuring bone mineral density.
The most common typology, and the one to which the next chapters of this article will refer with the sole term of MOC, is the so-called MOC DEXA . Also known as Dual Energy X-ray Absorption (in English Dual-Energy X-ray Absorptiometry ), the MOC DEXA provides, for the quantification of bone mineral density, the use of X-rays at two different energy levels.
Among the less used types, compared to the DEXA MOC, we note:
- The SPA, that is the Photonic Single-radius Absorbimetry . It involves the use of a radioactive substance. It is a measurement technique that was more in vogue in the past.
- The DPA, that is the Photonic Double-ray Absorbimetry . Like the previous SPA, it involves the use of a radioactive substance. It is an increasingly less practiced measurement technique.
- Computerized Quantitative Tomography . Also known as MOC QTC, it works similarly to normal Computerized Axial Tomography.
- Quantitative bone ultrasonography . Also known as MOC QUS, it involves the use of ultrasounds, which are not at all harmful to humans.
Its diagnostic power, however, is lower than that of the previous types of MOCs.
The MOC is a test indicated for various purposes, including:
- The diagnosis of conditions such as osteoporosis and osteopenia, which are characterized by a reduction in bone mineral density compared to the levels considered normal;
- The evaluation of how and if the drugs are working for the aforementioned conditions. The knowledge of how effective a certain drug therapy is is useful for the doctor to understand if it is necessary or not to make a change;
- Monitoring the effects on the skeleton of prolonged intake of corticosteroid drugs (eg: prednisone). Corticosteroids are powerful anti-inflammatories, whose use for long periods of time can have several side effects, including osteopenia or osteoporosis.
- The estimate of how much an individual is at risk of skeletal fractures;
- The monitoring of conditions that, among the various symptoms caused, also determine a lowering of bone mineral density (secondary osteopenia or osteoporosis). The conditions in question include: multiple myeloma, Cushing's syndrome, hyperthyroidism, hyperparathyroidism, early menopause, vitamin D deficiency and alcoholism.
OSTEOPOROSIS AND OSTEOPENIA
Osteoporosis is a common systemic disease of the skeleton, which causes a strong weakening of the bones. This weakening originates from the deterioration of the microarchitecture of the bone tissue and from the consequent reduction of the bone mineral mass. Due to the aforementioned bone weakening, the bones of people with osteoporosis are more fragile and prone to fractures.
Osteopenia is a condition very similar to osteoporosis; to distinguish it from the latter are the lower degree of reduction in bone mineral density and the consequent lower risk of skeletal fractures. In other words, osteopenia is mild osteoporosis.
Osteopenia and osteoporosis are two typical conditions of advanced age: in the female population, it is particularly widespread from the age of 65 and up, but in the male population, it is particularly common starting from the age of 70 and up.
The tendency of the elderly to develop osteopenia and osteoporosis is the reason why doctors recommend, for women aged 65 and over with a history of fractures and for men aged 70 and above with a past history of fractures, the execution of the MOC every two years.
|Conditions favoring osteoporosis and osteopenia:|
The MOC does not provide any particular preparation.
In fact, the only preparatory measure, to which patients must adhere, concerns clothing to be worn on the day of the exam and consists in avoiding any dress or accessory (eg, necklaces, earrings, etc.) with metal parts.
In general, the places where the MOC is carried out are the hospital radiology department or hospital clinics specializing in radiology and imaging diagnostics .
The first part of the procedure consists in the accommodation and positioning of the patient, on the table combined with the X-ray emission instrument, necessary for measuring bone mineral density.
For the success of the exam, the patient must maintain the position that the radiologist or the radiologist has imposed.
Unless otherwise indicated, no undressing is envisaged.
Only once the positioning is finished can the second part of the procedure begin, which consists in exposing the patient to X-rays.
After the exposure, the test can be considered concluded. The patient, therefore, can get up from the table on which he was lying and immediately return home.
WHAT HAPPENS DURING X-RAY EXPOSURE?
Without too many details, in striking the patient's body, X-rays are absorbed, in part, by the soft tissues, and in part by the bone tissues.
While absorption by soft tissues is useless for diagnostic purposes, absorption by bone tissues is what is needed for the quantification of bone mineral density.
In fact, this absorption varies in relation to the bone mineral mass of the subject examined.
WHAT HAS THE MEASUREMENT OF BONE MINERAL DENSITY MEAN?
On the occasion of the MOC, the bones from which the doctors generally derive the values of an individual's bone mineral density are: the vertebrae of the vertebral column, the bony portions that constitute the two articulations of the hip, the most important thoracic bones, the ulna and the radius of the forearm, the phalanges of the toes or hands and the heel.
Central MOC and peripheral MOC: what are they?
When MOC quantifies bone mineral density from the bones of the spine, the hip and / or the most important bones of the thorax, it takes the specific name of central MOC .
When instead the MOC quantifies the bone mineral density from the bones of the forearm, the calcaneus and / or the phalanges, it takes the name of peripheral MOC (P-DEXA, where P stands for "peripheral").
Very often, to thoroughly understand the bone mineral density of an individual, doctors subject the latter to both a central MOC and a peripheral MOC.
HOW MUCH HAS THE MOC?
As a rule, the MOC lasts 20 to 30 minutes.
Risks and complications
Like all X-ray tests, the MOC is to be considered a minimally invasive procedure, as it involves exposing the patient to a low dose of ionizing radiation, harmful to human beings.
Ionizing radiation aside, MOC has no other side effects; therefore, it is painless, leaves no mark on the skin, etc.
The MOC is contraindicated to:
- Pregnant women, as the ionizing radiation emitted by the instrumentation could cause fetal anomalies, thus compromising normal fetal development.
- Subjects with a metal hip prosthesis (if the hip is one of the sites investigated by the MOC);
- Subjects subjected to spinal fusion (if the spine is one of the sites investigated by the MOC);
- The people who have undergone in recent times (10 days before is the maximum limit) to an X-ray examination with contrast medium (eg: barium). Unlike the previous ones, it is a temporary contraindication. In fact, once the body has completely eliminated the contrast medium, the individual who needs the MOC can undergo the latter without any danger.
The MOC describes the bone mineral density of an individual through two parameters, named by the medical " T score " and " Z score ".
The " T score " is the measure of how much the bone mineral density value of the examined subject differs from the bone mineral density value of the reference, which is the healthy population of 25-30 years and of the same sex.
The " Z score ", on the other hand, is the measure of how much the bone mineral density value of the examined subject differs from the value of bone mineral density of another reference, which is the healthy population of the same age and sex.
In the diagnostic field, the " T score " is the parameter of greatest interest and use:
- Its negative value, compared to the reference, means low bone mineral density, therefore greater bone fragility and predisposition to skeletal fractures.
- A positive value, compared to the reference, means high bone mineral density, therefore bones more resistant and less prone to fractures.
" T SCORE " AND DIAGNOSIS OF OSTEOPENIA AND OSTEOPOROSIS
The " T score " is a fundamental parameter in the diagnosis of two important conditions such as osteoporosis and osteopenia.
In fact, doctors talk about osteopenia, when the " T score " falls within the range of values ranging from -1 excluding to -2.5 inclusive, while they speak of osteoporosis, when the " T score " takes values below -2, 5 excluded.
|T score value|
<-1 and ≥ -2.5
<-2.5 with fracture
WHAT CAN ALTER THE RESULTS OF A MOC?
To alter the results of a MOC can be various factors / conditions, including:
- An incorrect position of the patient on the table combined with X-ray equipment;
- The presence of a fracture of the bones for which the MOC measured bone mineral density;
- Having performed the diagnostic test less than 10 days after a previous radiological examination with contrast medium.
WHEN ARE THE RESULTS READY?
Except in special urgencies, the results of the MOC are ready, generally, after 2-3 days, from the execution of the test.
Summary of conditions that can cause secondary osteoporosis, identifiable by MOC:
- Endocrine diseases (eg hypogonadism, Cushing's syndrome, hyperparathyroidism, hyperthyroidism or excess thyroxine)
- Rheumatoid arthritis
- Vitamin D malabsorption or deficiency (eg, Crohn's disease or celiac disease)
- Chronic kidney diseases
- Chronic liver disease
- Corticosteroid drug abuse