JP6473882B1 - How to determine the shooting time - Google Patents
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- 239000002872 contrast media Substances 0.000 claims abstract description 43
- 238000003384 imaging method Methods 0.000 claims abstract description 38
- 210000000709 aorta Anatomy 0.000 claims abstract description 26
- 238000000034 method Methods 0.000 claims abstract description 22
- 210000002376 aorta thoracic Anatomy 0.000 claims abstract description 20
- 210000000702 aorta abdominal Anatomy 0.000 claims description 9
- 210000000038 chest Anatomy 0.000 claims description 9
- 230000003187 abdominal effect Effects 0.000 claims description 5
- 238000013170 computed tomography imaging Methods 0.000 claims description 4
- 210000001015 abdomen Anatomy 0.000 claims description 3
- 208000007474 aortic aneurysm Diseases 0.000 description 3
- 230000017531 blood circulation Effects 0.000 description 3
- 208000017169 kidney disease Diseases 0.000 description 3
- 206010062237 Renal impairment Diseases 0.000 description 2
- 208000002223 abdominal aortic aneurysm Diseases 0.000 description 2
- 210000004197 pelvis Anatomy 0.000 description 2
- 231100000857 poor renal function Toxicity 0.000 description 2
- 208000025494 Aortic disease Diseases 0.000 description 1
- 208000002251 Dissecting Aneurysm Diseases 0.000 description 1
- 206010002895 aortic dissection Diseases 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000002405 diagnostic procedure Methods 0.000 description 1
- 238000002224 dissection Methods 0.000 description 1
- 238000001990 intravenous administration Methods 0.000 description 1
- 210000003734 kidney Anatomy 0.000 description 1
- 230000003907 kidney function Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
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Abstract
【課題】大動脈における造影剤の移動速度を算出することにより、必要最小限の造影剤で大動脈造影CTを行うことを可能にする。
【解決手段】上行大動脈基部のレベルでタイミングボーラス法の撮影を行い、上行大動脈と下行大動脈の2ヶ所の時間濃度曲線を描く。このピーク時間の差から大動脈における造影剤の移動速度を算出し、本番の撮影にかける時間を決定する。この方法により、大動脈造影CTを必要最小限の造影剤で撮影できるようになる。
【選択図】図2By calculating a moving speed of a contrast medium in an aorta, it is possible to perform an aortic contrast CT with a minimum necessary contrast medium.
Timing bolus imaging is performed at the level of the base of the ascending aorta, and two time density curves are drawn for the ascending aorta and the descending aorta. The moving speed of the contrast medium in the aorta is calculated from the difference in peak time, and the time taken for actual imaging is determined. With this method, aortic contrast CT can be imaged with the minimum necessary contrast medium.
[Selection] Figure 2
Description
本発明は、大動脈造影CTを撮影する際に、必要最小限の造影剤で撮影するための手法である。 The present invention is a technique for imaging with a minimum necessary contrast agent when imaging an aortic contrast CT.
大動脈瘤や解離の診断において、大動脈造影CTは最も一般的に使われている診断法である。撮影範囲が胸部から骨盤部と広いため、従来は70-100mL程度の造影剤を20秒程度かけて注入して撮影することが定石であった。 In the diagnosis of aortic aneurysm and dissection, aortic CT is the most commonly used diagnostic method. Since the imaging range is wide from the chest to the pelvis, it has been the usual practice to inject a 70-100 mL contrast medium over about 20 seconds.
ところが、造影剤は腎臓から体外に排泄されるため、造影剤使用量が増えると、腎機能の低下を引き起こす、いわゆる造影剤腎症の原因となる。大動脈疾患を抱える患者の多くは腎機能が低下していることが多いため、検査で使用する造影剤量を減らすことができれば、造影剤腎症のリスクを減らすことにつながる。 However, since the contrast agent is excreted from the kidney to the outside of the body, when the amount of contrast agent used increases, it causes so-called contrast nephropathy that causes a decrease in renal function. Many patients with aortic disease often have impaired renal function. Therefore, if the amount of contrast medium used in the test can be reduced, the risk of contrast medium nephropathy will be reduced.
従来の撮影で造影剤の使用量を減らせなかった理由は、大動脈全体を均一に造影剤で満たした状態で撮影を行うという考え方に基づいていたからである。ところが、実際のCT撮影は約4cmの検出器を用いて胸部から骨盤部にかけてらせん状に撮影していくため、撮影している部分のみに造影剤が満たされていれば大動脈が造影された画像を作成できる。ところが、大動脈の血流は患者ごとに異なる。従って、造影剤が大動脈に到着する時間と大動脈を通過する速度を計測する方法が確立すれば、最小限の造影剤でCT撮影が行えるようになる。 The reason why the amount of contrast medium used in conventional imaging could not be reduced is based on the idea that imaging is performed in a state where the entire aorta is uniformly filled with the contrast medium. However, since actual CT imaging uses a detector of about 4 cm to take a spiral from the chest to the pelvis, an image of the aorta contrasted if only the part being imaged is filled with contrast medium Can be created. However, the blood flow in the aorta varies from patient to patient. Therefore, if a method for measuring the time at which the contrast medium arrives at the aorta and the speed at which it passes through the aorta is established, CT imaging can be performed with a minimum of contrast medium.
造影剤を注射してから大動脈に造影剤が到着する時間を推測する方法としてタイミングボーラス法という手法が一般的に用いられている。これは、少量造影剤(約10mL)を注射して、大動脈を1秒間隔で連続撮影し、造影剤がピークを迎える時間を推測する方法である(図1)。従来では、1か所のみの時間濃度曲線を計測し、ピークを迎える時間のみを記録していた(図1)。 A method called a timing bolus method is generally used as a method for estimating the time at which a contrast medium arrives at the aorta after the contrast medium is injected. In this method, a small amount of contrast medium (approximately 10 mL) is injected, the aorta is continuously photographed at 1-second intervals, and the time when the contrast medium reaches its peak is estimated (Figure 1). In the past, only one time concentration curve was measured and only the time to reach the peak was recorded (Fig. 1).
本発明では、上行大動脈基部の高さでタイミングボーラス撮影を行い、上行大動脈と下行大動脈の2ヶ所の時間濃度曲線を計測する(図2)。それぞれの時間濃度曲線のピーク時間の差を記録する(T1)。次に、胸部大動脈の長さ(L0×2)、胸部の撮影範囲長(L1)、腹部の撮影範囲長(L2)も記録する。これらの値を用いて、下記の式で撮影にかける時間を計算する。ただし、今回の計測法では腹部大動脈での血流までは正確に計測できないため、以下の方法を用いて撮影時間を決定する。まず、腹部大動脈では胸部大動脈と比較して流速が低下するため、速度を6割とする。さらに、腹部大動脈瘤がある場合やステント治療後では所定の時間(C)を追加する。これらの仮定の元、最終的な撮影時間を決定する。ただし、血流が非常に速い場合(撮影時間が短く計算される場合)と遅い場合(撮影時間が長く計算される場合)は経験的にこの推測式が実態と乖離するため、撮影時間の下限は10秒、上限は20秒として撮影する。 In the present invention, timing bolus imaging is performed at the height of the base of the ascending aorta, and two time density curves of the ascending aorta and the descending aorta are measured (FIG. 2). Record the difference in peak time for each time concentration curve (T1). Next, the length of the thoracic aorta (L0 × 2), the imaging range length of the chest (L1), and the imaging range length of the abdomen (L2) are also recorded. Using these values, the time taken for photographing is calculated by the following formula. However, since the current measurement method cannot accurately measure blood flow in the abdominal aorta, the imaging time is determined using the following method. First, since the flow velocity is lower in the abdominal aorta than in the thoracic aorta, the speed is 60%. Furthermore, when there is an abdominal aortic aneurysm or after stent treatment, a predetermined time (C) is added. Based on these assumptions, the final shooting time is determined. However, if the blood flow is very fast (when the shooting time is calculated short) and slow (when the shooting time is calculated long), this estimation formula empirically deviates from the actual situation, so the lower limit of the shooting time Shoot for 10 seconds and the upper limit is 20 seconds.
実際の撮影では約40mLの造影剤を9秒注入し、タイミングボーラス撮影で下行大動脈がピークを迎える時間から撮影を開始し、上述で計算した撮影時間(T)で撮影する。この方法を用いることで、従来の撮影法と比較して造影剤使用量を半分以下にすることが可能となる。
解決しようとする課題は、大動脈造影CTで使用する造影剤量を必要最小限に減らすことである。 The problem to be solved is to reduce the amount of contrast agent used in aortic contrast CT to the minimum necessary.
本発明では、造影剤の大動脈におけるピークを追跡して撮影できるため、撮影に必要な造影剤が最小限で済む。 In the present invention, since the peak of the contrast medium in the aorta can be tracked and imaged, the contrast medium required for imaging can be minimized.
本発明では、大動脈全体を造影剤で満たす必要がなく、撮影している部位のみが造影されていればよいため、撮影に必要な造影剤は約40mL程度でよく、従来の使用量の半分以下となる。 In the present invention, it is not necessary to fill the entire aorta with the contrast medium, and only the site being imaged needs to be imaged. Therefore, the contrast medium required for imaging may be about 40 mL, which is less than half of the conventional usage. It becomes.
タイミングボーラス法で2ヶ所の時間濃度曲線を描くことで、造影剤の移動速度を算出できた。 The moving speed of the contrast agent was calculated by drawing two time density curves using the timing bolus method.
図2は本発明の手法を用いて、大動脈の撮影にかける時間を決定する過程を示している。 FIG. 2 shows a process of determining the time taken for imaging the aorta using the method of the present invention.
上行大動脈と下行大動脈のピーク差(T1)は3秒である。胸部大動脈長(L0×2)は140mmであるため、胸部大動脈は47mm/s (V1)で撮影すればよい。したがって、腹部大動脈を撮影する速度(V2)は28mm/sとなる。胸部撮影長(L1)は125mm、腹部撮影長(L2)は435mmであり、さらに45mmの腹部大動脈瘤があるため、撮影時間(T)は2.7+15.5+1 = 19.2秒と計算される。 The peak difference (T1) between the ascending aorta and descending aorta is 3 seconds. Since the thoracic aorta length (L0 × 2) is 140 mm, the thoracic aorta may be imaged at 47 mm / s (V1). Therefore, the speed (V2) for imaging the abdominal aorta is 28 mm / s. Since the chest imaging length (L1) is 125 mm, the abdominal imaging length (L2) is 435 mm, and there is a 45 mm abdominal aortic aneurysm, the imaging time (T) is calculated as 2.7 + 15.5 + 1 = 19.2 seconds.
図3は本発明の方法で計算した19.2秒の時間をかけて、40mLの造影剤で大動脈を撮影した際の大動脈3次元画像である。 FIG. 3 is a three-dimensional image of the aorta when the aorta is imaged with 40 mL of contrast medium over a period of 19.2 seconds calculated by the method of the present invention.
大動脈造影CTにおける造影剤使用量を従来の半分以下にできるため、造影CTによる造影剤腎症の合併症を引き起こすリスクを減らすことが可能である。また、腎機能が低下している患者でも大動脈造影CT検査が行えるようになるため、この検査の適応が広がる。 Since the amount of contrast medium used in aortic contrast CT can be reduced to less than half of the conventional level, the risk of causing complications of contrast medium nephropathy due to contrast CT can be reduced. In addition, aortic contrast CT can be performed even in patients with impaired renal function, so the indication of this test is expanded.
1 下行大動脈
2 上行大動脈
1 descending aorta
2 Ascending aorta
Claims (4)
上行大動脈基部を通る断面を連続撮影して得られた画像から、上行大動脈と下行大動脈の時間濃度曲線を作成するステップと、
上行大動脈の時間濃度曲線のピーク時間と下行大動脈の時間濃度曲線のピーク時間の時間差と、胸部大動脈の長さとを取得するステップと、
前記時間差と、前記胸部大動脈の長さとに基づいて胸部大動脈造影剤移動速度を算出するステップと、
胸部の撮影範囲長を取得し、前記胸部の撮影範囲長と前記胸部大動脈造影剤移動速度とに基づいて、胸部の撮影時間を算出するステップと、
を備える、撮影時間の決定方法。A method for determining imaging time in aorta CT imaging,
Creating a time-concentration curve of the ascending aorta and descending aorta from images obtained by continuously photographing a cross section passing through the base of the ascending aorta;
Obtaining the time difference between the peak time of the time density curve of the ascending aorta and the peak time of the time density curve of the descending aorta, and the length of the thoracic aorta;
Calculating a thoracic aorta contrast agent moving speed based on the time difference and the length of the thoracic aorta;
Obtaining an imaging range length of the chest, and calculating an imaging time of the chest based on the imaging range length of the chest and the thoracic aorta contrast medium moving speed;
A method for determining a shooting time.
腹部の撮影範囲長を取得し、前記腹部の撮影範囲長と前記腹部大動脈造影剤移動速度とに基づいて、腹部の撮影時間を算出するステップと、を備える、請求項1に記載の撮影時間の決定方法。Calculating an abdominal aorta contrast agent moving speed that is slower than the thoracic aorta contrast agent moving speed based on the thoracic aorta contrast agent moving speed and a predetermined coefficient;
The method includes: obtaining an abdominal imaging range length, and calculating an abdominal imaging time based on the abdominal imaging range length and the abdominal aorta contrast medium moving speed. Decision method.
前記胸部大動脈造影剤移動速度は、以下の式に基づいて算出され、
V1=L0/T1
前記腹部大動脈造影剤移動速度は、以下の式に基づいて算出され、
V2=0.6×V1
前記撮影開始からの撮影時間は、以下の式に基づいて算出され、
T=(L1/V1)+(L2/V2)+C
V1は、前記胸部大動脈造影剤移動速度であり、
L0は、前記胸部大動脈の長さであり、
T1は、前記時間差であり、
V2は、前記腹部大動脈造影剤移動速度であり、
Tは、前記撮影開始からの撮影時間であり、
L1は、前記胸部の撮影範囲長であり、
L2は、前記腹部の撮影範囲長であり、
Cは補正値であって、腹部大動脈の径が40から49mmの条件では1秒であり、腹部大動脈の径が50mm以上の条件では2秒であり、腹部大動脈ステント治療後という条件では1秒であり、いずれの条件も満たさない場合は0秒である、請求項2に記載の撮影時間の決定方法。Based on the imaging time of the chest and the imaging time of the abdomen, the step of calculating the imaging time from the start of imaging in aortic CT imaging,
The thoracic aorta contrast agent moving speed is calculated based on the following formula:
V1 = L0 / T1
The abdominal aorta contrast agent moving speed is calculated based on the following formula:
V2 = 0.6 × V1
The shooting time from the start of shooting is calculated based on the following formula:
T = (L1 / V1) + (L2 / V2) + C
V1 is the thoracic aorta contrast agent moving speed,
L0 is the length of the thoracic aorta,
T1 is the time difference,
V2 is the abdominal aorta contrast agent moving speed,
T is the shooting time from the start of shooting,
L1 is the imaging range length of the chest,
L2 is the imaging range length of the abdomen,
C is a correction value, which is 1 second when the diameter of the abdominal aorta is 40 to 49 mm, 2 seconds when the diameter of the abdominal aorta is 50 mm or more, and 1 second after the abdominal aortic stent treatment. The method of determining an imaging time according to claim 2, wherein the time is 0 second when none of the conditions is satisfied.
算出された前記撮影開始からの撮影時間が20秒より長い場合は、前記撮影開始からの撮影時間を20秒とする、請求項3に記載の撮影時間の決定方法。When the calculated shooting time from the start of shooting is shorter than 10 seconds, the shooting time from the start of shooting is set to 10 seconds,
The method of determining a shooting time according to claim 3, wherein when the calculated shooting time from the start of shooting is longer than 20 seconds, the shooting time from the start of shooting is set to 20 seconds.
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Free format text: JAPANESE INTERMEDIATE CODE: R250 |