6/20/2023 0 Comments Life of daniel bible study![]() ![]() According to this now well-performed TCD ratio, the angiographic finding of vasospasm was fortuitous, at least if this index is used independently. The actual LI in this case is 2.1, which indicates hyperemia (Fig. 2 is an obvious mistake and readers need to be cautioned from making the same error. Indeed, TAP should be compared when the Lindegaard Index (LI) is used, but comparing TAMAX/TAMEAN as is performed in Fig. 2, where in the TCCS image, TAP is correctly used, but in the transcervical insonation, TAMV is used instead of TAP. Since in TCCS, the velocity considered is the TAMAX, using TAMEAN instead of TAP leads to underestimating velocities. While both are “mean” velocities, TAMEAN is approximately half the TAMAX. Second, when moving from a bTCD technique to the Duplex technique, practitioners must be aware of the “mean velocities” recorded by the ultrasound machine: time-averaged maximum velocity, known as TAMAX or TAP and time-averaged mean velocity, also known as TAMEAN or TAMV. Note: the waveform in ( b) is consistent with an external carotid artery flow, given its sharp systolic upstroke, high-resistance velocity profile, and early diastolic notch (another mistake that should be taken into account) It is thus clearly incorrect to use different “mean velocities” when calculating the LI, such as TAP/TAMEAN. The correct Lindegaard Index (Middle cerebral artery TAP/internal carotid artery TAP) in this case is 123/58, equal to 2.1 (corresponding to hyperemia if considered independently). In TCCS, time-averaged maximum or peak velocities are the “mean” velocities that should be considered. Time-averaged mean velocity is not recorded in ( a), but is shown in ( b) as TAM, traced in the middle of the Doppler spectra (white arrow). There is also no doubt in a that is TAP, because pulsatility index (PI) is calculated using this value. As depicted from the trace of the envelope of the Doppler spectra (yellow arrows), time-averaged maximum velocity is recorded, namely, TAV (time-averaged velocity) in ( a) and TAP (time-averaged peak velocity) in ( b). ![]() Note the different and confusing nomenclature regarding “mean velocities”. Particularly in patients with a decompressive craniectomy, an alternative MLS measurement technique is well validated against CT. Practitioners should be aware that the MLS measurement by TCCS is not reliable in the presence of bone defects (like decompressive craniectomy or skull fractures), temporal cephalohematoma, or changes in intracranial anatomy secondary to trauma, citing the most common examples observed in daily practice. To the authors´ knowledge, whether methodologically correct or not, there are no study validating either of them. 1 of the original article, measuring the distance to the contralateral cranial bone is not described in the original technique, it is unnecessary and adds complexity thus, it should not be taken into account, as is the case with the mentioned “C and D” technique. ![]() While proposed by authors’ as an “internal standard”, as shown in Fig. In the first place, regarding the midline shift (MLS) measurement technique by TCCS, (A-B)/2 is well-studied and validated against CT. ![]()
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