Non-perfused elements of other types of vascular rings (e.g. left arch with atretic (closed) end) or the ligamentum arteriosum might be difficult to visualize by echocardiography. Computed tomography (CT):
Computed tomography after application of contrast media is usually diagnostically accurate. It shows the relationship of the arches to the trachea and bronchi. Magnetic resonance imaging (MRI):
Magnetic resonance imaging provides excellent images of the trachea and surrounding vascular structures and has the advantage of not using radiation for imaging compared to Computed tomography. Cardiac catherization/aortography:
Today patients with double aortic arch usually only undergo cardiac catherization to evaluate the hemodynamics and anatomy of associated congenital cardiac defects. Through a catheter in the ascending aorta contrast media is injected and the resulting aortography may be used to delineate the anatomy of the double aortic arch including sites of narrowing in the left aortic arch. Aortography can also be used to visualize the origin of all head and arm vessels originating from the two arches. Classification
Double aortic arch is a subtype of complete vascular ring. There are three types of double aortic arch:

Right dominant arch (about 70% of surgical cases)
Balanced or codominant (about 5%): both arches are of equal size
Left dominant (about 25%)Double aortic arch with right dominant arch:
Normally there is only one (left) aortic arch. In patients with double aortic arch the ascending aorta arises normally from the left ventricle but then divides into two arches, a left and a right aortic arch which join posteriorly to become the descending aorta.
The relationship between an individual and their hallucinations is personal, and everyone interacts with their troubles in different ways. There are those who hear solely malevolent voices, solely benevolent voices, those that hear a mix of the two, and those that see them as either malevolent or benevolent and not believing the voice. Mood disorders and dementias
Mood disorders such as bipolar disorder and major depression have also been known to correlate with auditory hallucinations, but tend to be milder than their psychosis-induced counterpart. Auditory hallucinations are a relatively common sequelae of major neurocognitive disorders (formerly dementia) such as Alzheimers disease. Transient causes
Auditory hallucinations have been known to manifest as a result of intense stress, sleep deprivation, and drug use. Auditory hallucinations can also occur in mentally healthy individuals during the altered state of consciousness while falling asleep (hypnagogic hallucinations) and waking up (hypnopompic hallucinations).High caffeine consumption has been linked to an increase in the likelihood of experiencing auditory hallucinations. A study conducted by the La Trobe University School of Psychological Sciences revealed that as few as five cups of coffee a day could trigger the phenomenon. Intoxication of psychoactive drugs such as PCP, amphetamines, cocaine, marijuana and other substances can produce hallucinations in general, especially in high doses. Withdrawal from certain drugs such as alcohol, sedatives, hypnotics, anxiolytics, and opioids can also produce hallucinations, including auditory. Pathophysiology
The following areas of the brain have been found to be active during auditory hallucinations, through the use of fMRIs.