Systematic Approach to Brain Tumors
腦腫瘤的系統性方法

When we analyze a potential brain tumor, there are many questions that need to be answered.
當我們分析潛在的腦腫瘤時，有許多問題需要回答。
Since different tumors occur in different age groups we first of all need to know the age of the patient.
由於不同的腫瘤發生在不同的年齡組，我們首先需要知道患者的年齡。
Next we need to know where the lesion is located - is it intra- or extra-axial and in what anatomical compartment does it lie?
接下來我們需要知道病變的位置 - 它是軸內還是軸外，它位於哪個解剖隔室中？
Is it located in the sellar or pontocerebellar region for example?
例如，它位於蝶鞍區還是小腦橋區？
Is it a solitary mass or is there multi-focal disease?
是孤立性腫塊還是多灶性疾病？
On CT and MR we look for tissue characteristics like calcifications, fat, cystic components, contrast enhancement and signal intensity on T1WI, T2WI and DWI.
在 CT 和 MR 上，我們尋找組織特徵，如 T1WI、T2WI 和 DWI 上的鈣化、脂肪、囊性成分、對比增強和信號強度。
Most brain tumors are of low signal intensity on T1WI and high on T2WI.
大多數腦腫瘤在 T1WI 上信號強度低，在 T2WI 上信號強度高。
Therefore high signal intensity on T1WI or low signal on T2WI can be an important clue to the diagnosis.
因此，T1WI 上的高信號強度或 T2WI 上的低信號可能是診斷的重要線索。
Finally we have to consider the possibility that we are dealing with a lesion that simulates a tumor - like an abscess, MS-plaque, vascular malformation, aneurysm or an infarct with luxury perfusion.
最後，我們必須考慮我們正在處理模擬腫瘤的病變的可能性 - 如膿腫、MS 斑塊、血管畸形、動脈瘤或具有豪華灌注的梗塞。

Incidence of CNS tumors  CNS 腫瘤的發病率

Roughly one-third of CNS tumors are metastatic lesions, one third are gliomas and one-third is of non-glial origin.
大約 1/3 的 CNS 腫瘤是轉移性病變，1/3 是神經膠質瘤，1/3 是非神經膠質起源的。
Glioma is a non-specific term indicating that the tumor originates from glial cells like astrocytes, oligodendrocytes, ependymal and choroid plexus cells.
神經膠質瘤是一個非特異性術語，表明腫瘤起源於神經膠質細胞，如星形膠質細胞、少突膠質細胞、室管膜和脈絡叢細胞。
Astrocytoma is the most common glioma and can be subdivided into the low-grade pilocytic type, the intermediate anaplastic type and the high grade malignant glioblastoma multiforme (GBM).
星形細胞瘤是最常見的神經膠質瘤，可細分為低級別毛細胞型、中間間變型和高級別型 惡性多形性膠質母細胞瘤 （GBM）。
GBM is the most common type (50% of all astrocytomas).
GBM 是最常見的類型（佔所有星形細胞瘤的 50%）。
The non-glial cel tumors are a large heterogenous group of tumors of which meningioma is the most common.
非神經膠質細胞瘤是一大組異質性腫瘤，其中腦膜瘤是最常見的。

Note: since the publication of this article, these numbers have changed and metastases now outnumber the primary brain tumors and are increasing in incidence as overall cancer survival improves.
注意：自本文發表以來，這些數字發生了變化，轉移瘤的數量現在超過了原發性腦腫瘤，並且隨著癌症總生存率的提高，發病率也在增加。

Age distribution  年齡分佈

The age of the patient is an important factor for the differential diagnosis.
患者年齡是鑒別診斷的重要因素。
Specific tumors occur under the age of 2, like choroid plexus papillomas, anaplastic astrocytomas and teratomas.
特定腫瘤發生在 2 歲以下，如脈絡叢狀瘤、間變性星形細胞瘤和畸胎瘤。
In the first decade medulloblastomas, astrocytomas, ependymomas, craniopharyngeomas and gliomas are most common, while metastases are very rare.
在第一個十年中，髓母細胞瘤、星形細胞瘤、室管膜瘤、顱咽瘤和神經膠質瘤最常見，而轉移瘤則非常罕見。
When they do occur at this age, metastases of a neuroblastoma are the most frequent.
當它們確實發生在這個年齡時，神經母細胞瘤的轉移是最頻繁的。
In adults about 50% of all CNS lesions are metastases.
在成人中，大約50%的 CNS 病變是轉移。
Other common tumors in adults are astrocytomas, glioblastoma multiforme, meningiomas, oligodendrogliomas, pituitary adenomas and schwannomas.
成人其他常見腫瘤包括星形細胞瘤、多形性膠質母細胞瘤、腦膜瘤、少突膠質細胞瘤、垂體腺瘤和神經鞘瘤。
Astrocytomas occur at any age, but glioblastoma multiforme is mostly seen in older people.
星形細胞瘤發生在任何年齡，但多形性膠質母細胞瘤主要見於老年人。

Although cancer is rare in children, brain tumors are the most common type of childhood cancer after leukemia and lymphoma.
雖然癌症在兒童中很少見，但腦瘤是繼白血病和淋巴瘤之後最常見的兒童癌症類型。
Most of the tumors in children are located infratentorially.
兒童的大多數腫瘤位於幕下。
The most common supra- and infratentorial tumors are listed in the table on the left.
最常見的幕上和幕下腫瘤列在左表中。

The most common tumors in adults are listed in the table on the left.
成人中最常見的腫瘤列在左表中。
Note that metastases are by far the most common.
請注意，轉移是迄今為止最常見的。
It is important to realize that 50% of metastases are solitary.
重要的是要認識到 50% 的轉移是孤立的。
Particularly in the posterior fossa, metastases should be in the top 3 of the differential diagnostic list.
特別是在後顱窩中，轉移灶應位於鑒別診斷清單的前3位。
Hemangioblastoma is an uncommon tumor, but it is the most common primary intra-axial tumor in the adult.
血管母細胞瘤是一種罕見的腫瘤，但它是成人中最常見的原發性軸內腫瘤。
Supratentorially, metastases are also the most common tumors, followed by gliomas.
在幕上，轉移也是最常見的腫瘤，其次是神經膠質瘤。

Intra- versus Extraaxial  軸內與軸外

When we study an intracranial mass, the first thing we want to know is whether the mass lies in- or outside of the brain.
當我們研究顱內腫塊時，我們首先想知道的是腫塊是位於大腦內部還是外部。
If it is outside the brain or extra-axial, then the lesion is not actually a brain tumor, but derived from the lining of the brain or surrounding structures.
如果它在大腦外部或軸外，那麼病變實際上不是腦腫瘤，而是源自大腦內膜或周圍結構。
Eighty percent of these extra-axial lesions will be either a meningioma or a schwannoma.
這些軸外病變中有 80% 是腦膜瘤或神經鞘瘤。
On the other hand, in an adult an intra-axial tumor will be a metastasis or astrocytoma in 75% of cases.
另一方面，在成人中，軸內腫瘤在75%的病例中將是轉移或星形細胞瘤。

The T2W-images show a schwannoma located in the cerebellopontine angle (CPA).
T2W 圖像顯示位於橋小腦角 （CPA） 的神經鞘瘤。
This case nicely demonstrates the typical signs of an extra-axial tumor.
這個病例很好地展示了軸外腫瘤的典型癥狀。
There is a CSF cleft (yellow arrow).
有 CSF 裂（黃色箭頭）。
The subarachnoid vessels that run on the surface of the brain are displaced by the lesion (blue arrow).
在大腦表面走行的蛛網膜下腔血管被病變移位（藍色箭頭）。
There is gray matter between the lesion and the white matter (curved red arrow).
病變和白質之間有灰質（彎曲的紅色箭頭）。
The subarachnoid space is widened because growth of an extra-axial lesion tends to push away the brain.
蛛網膜下腔變寬，因為軸外病變的生長往往會推開大腦。
All these signs indicate that this is a typical extra-axial tumor.
所有這些跡象都表明這是一種典型的軸外腫瘤。
In the region of the CPA 90% of the extra-axial tumors are schwannomas.
在 CPA 區域，90% 的軸外腫瘤是神經鞘瘤。

Another sign of an extra-axial origin is a broad dural base or a dural tail of enhancement as is typically seen in meningiomas.
軸外起源的另一個跡象是寬闊的硬腦膜基底或硬腦膜增強尾部，通常見於腦膜瘤。
This may also occur in other extra-axial tumors, but it is less common.
這也可能發生在其他軸外腫瘤中，但不太常見。
Another sign of an extra-axial origin are bony changes.
軸外起源的另一個跡象是骨變化。
Bony changes are seen in bone tumors like chordomas, chondrosarcomas and metastases.
骨變化見於骨腫瘤，如脊索瘤、軟骨肉瘤和轉移瘤。
They can also be secondary, as is seen in meningiomas and other tumors.
它們也可以是繼發性的，如腦膜瘤和其他腫瘤。

On the left an example of a meningioma with a broad dural base and a dural tail of enhancement.
左邊是腦膜瘤的例子，具有寬闊的硬腦膜基底和增強的硬腦膜尾部。
There is hyperostosis in the adjacent bone and the lesion enhances homogeneously.
鄰近骨有骨質增生，病變均勻增強。
Extra-axial tumors are not derived from brain tissue and do not have a blood-brain-barrier, so most of them enhance homogeneously.
軸外腫瘤不是來源於腦組織，也沒有血腦屏障，因此它們中的大多數都均勻增強。

Intra- vs Extra-axial (2)
軸內與軸外 （2）
The differentiation between intra-axial versus extra-axial is usually straight forward, but sometimes it can be very difficult and imaging in multiple planes may be necessary.
軸內和軸外之間的區別通常很簡單，但有時可能非常困難，可能需要在多個平面上成像。

The tumor in the case on the left was thought to be a falcine meningioma, i.e. extra-axial and was presented for surgery.
左側病例中的腫瘤被認為是鐮刀腦膜瘤，即軸外，並被送去手術。
This lesion surely has the appearance of a meningioma: these tumors can be hypointense on T2 due to a fibrocollageneous matrix or calcifications and frequently produce reactive edema in the adjacent white matter of the brain.
這種病變肯定具有腦膜瘤的外觀：由於纖維膠原基質或鈣化，這些腫瘤在 T2 上可能呈低信號，並經常在大腦的鄰近白質中產生反應性水腫。
However, there is gray matter on the anteromedial and posteromedial side of the lesion (red arrow).
然而，病變的前內側和后內側有灰質（紅色箭頭）。
This indicates that the lesion is intra-axial.
這表明病變位於軸內。
If the lesion was extra-axial the gray matter should have been pushed away.
如果病變是軸外的，則應將灰質推開。
This proved to be a melanoma metastasis.
這被證明是黑色素瘤轉移。

Local tumor spread (1)  局部腫瘤擴散 （1）

Astrocytomas spread along the white matter tracts and do not respect the bounderies of the lobes.
星形細胞瘤沿白質束擴散，不尊重肺葉的邊界。
Because of this infiltrative growth, in many cases the tumor is actually larger than can be depicted with MR.
由於這種浸潤性生長，在許多情況下，腫瘤實際上比 MR 所能描述的要大。
Ependymomas of the fourth ventricle in children tend to extend through the foramen of Magendie to the cisterna magna and through the lateral foramina of Luschka to the cerebellopontine angle (figure).
兒童第四腦室室管膜瘤傾向於通過Magendie孔延伸到大腦池，並通過 Luschka 外側孔延伸到小腦橋角（圖）。
Oligodendrogliomas typically show extension to the cortex.
少突膠質細胞瘤通常顯示向皮質延伸。

Subarachnoid seeding  蛛網膜下腔播種
Some tumors show subarachnoid seeding and form tumoral nodules along the brain and spinal cord.
一些腫瘤顯示蛛網膜下腔散發，並沿大腦和脊髓形成腫瘤結節。
This is seen in PNET, ependymomas, GBMs, lymphomas, oligodendrogliomas and choroid plexus papillomas.
這可見於 PNET、室管膜瘤、GBM、淋巴瘤、少突膠質細胞瘤和脈絡叢狀瘤。
Primitive neuroectodermal tumours (PNET) form a rare group of tumors, which develop from primitive or undifferentiated nerve cells.
原始神經外胚層腫瘤 （PNET） 是一組罕見的腫瘤，由原始或未分化的神經細胞發展而來。
These include medulloblastomas and pineoblastomas.
這些包括髓母細胞瘤和松果體母細胞瘤。

One of the most important roles of imaging is to assess the extent of a tumor.
影像學檢查最重要的作用之一是評估腫瘤的範圍。
This is shown in the case on the left in a patient who presented with multiple cranial nerve abnormalities.
這在左側的病例中顯示，該患者出現多發性顱神經異常。
On the images we see an extra-axial tumor in the region of the left cavernous sinus.
在圖像上，我們在左側海綿竇區域看到一個軸外腫瘤。
There is homogeneous enhancement with a broad dural tail.
有均勻的增強，硬腦膜尾部寬。
This is typical for a meningioma.
這是腦膜瘤的典型特徵。

Only by studying all the images we do appreciate that the actual extent of the tumor is greater than expected.
只有通過研究所有圖像，我們才能體會到腫瘤的實際範圍比預期的要大。
The tumor is situated in the pterygopalatine fossa and extends into the orbit.
腫瘤位於翼齶窩並延伸到眼眶。
It also spreads anteriorly into the middle cranial fossa
它還向前擴散到顱中窩

Local tumor spread (2)  局部腫瘤擴散 （2）
Another important consideration is the effect on the surrounding structures.
另一個重要的考慮因素是對周圍結構的影響。
Primary brain tumors are derived from brain cells and often have less mass effect for their size than you would expect, due to their infiltrative growth.
原發性腦腫瘤來源於腦細胞，由於浸潤性生長，其大小的質量效應通常比您預期的要小。
This is not the case with metastases and extra-axial tumors like meningiomas or schwannomas, which have more mass effect due to their expansive growth.
轉移瘤和腦膜瘤或神經鞘瘤等軸外腫瘤並非如此，它們由於生長廣泛而具有更大的佔位效應。

On the left is an image of a diffusely infiltrating intra-axial tumor occupying most of the right hemisphere with only a minimal mass effect.
左側是瀰漫性浸潤性軸內腫瘤的圖像，佔據了右半球的大部分，只有極小的佔位效應。
This is typical for the infiltrative growth seen in primary brain tumors.
這是原發性腦腫瘤中浸潤性生長的典型特徵。
There is no enhancement so this would probably be a low-grade astrocytoma.
沒有增強，所以這可能是一個低級別星形細胞瘤。

Midline crossing  中線交叉

The ability of tumors to cross the midline limits the differential diagnosis.
腫瘤穿過中線的能力限制了鑒別診斷。

• Glioblastoma multiforme (GBM) frequently crosses the midline by infiltrating the white matter tracts of the corpus callosum.
  多形性膠質母細胞瘤 （GBM） 經常通過浸潤胼胝體的白質束而越過中線。
• Radiation necrosis can look like recurrent GBM and can sometimes cross the midline.
  放射性壞死可能看起來像復發性 GBM，有時可以越過中線。
• Meningioma is an extra-axial tumor and can spread along the meninges to the contralateral side.
  腦膜瘤是一種軸外腫瘤，可沿腦膜擴散到對側。
• Lymphoma is usually located near the midline.
  淋巴瘤通常位於中線附近。
• Epidermoid cysts can cross the midline via the subarachnoid space.
  表皮樣囊腫可以通過蛛網膜下腔穿過中線。
• MS can also present as a mass lesion in the corpus callosum.
  MS 也可表現為胼胝體的佔位性病變。

Multifocal disease  多灶性疾病

Multiple tumors in the brain usually indicate metastatic disease (figure).
腦部多發性腫瘤通常提示轉移性疾病（圖）。
Primary brain tumors are typically seen in a single region, but some brain tumors like lymphomas, multicentric glioblastomas and gliomatosis cerebri can be multifocal.
原發性腦腫瘤通常出現在單個區域，但一些腦腫瘤，如淋巴瘤、多中心膠質母細胞瘤和腦膠質瘤病，可以是多灶性的。
Some tumors can be multifocal as a result of seeding metastases: this can occur in medulloblastomas (PNET-MB), ependymomas, GBMs and oligodendrogliomas.
由於接種轉移，一些腫瘤可能是多灶性的：這可能發生在髓母細胞瘤 （PNET-MB）、室管膜瘤、GBM 和少突膠質細胞瘤中。
Meningiomas and schwannomas can be multiple, especially in neurofibromatosis type II.
腦膜瘤和神經鞘瘤可以是多發性的，尤其是在II型神經纖維瘤病中。

Multiple brain tumors can be seen in phacomatoses:
多發性腦腫瘤可見於超聲瘤病：

• Neurofibromatosis I: optic gliomas and astrocytomas
  神經纖維瘤病 I：視神經膠質瘤和星形細胞瘤
• Neurofibromatosis II: meningiomas, ependymomas, choroid plexus papillomas (figure)
  神經纖維瘤病 II：腦膜瘤、室管膜瘤、脈絡叢狀瘤（圖）
• Tuberous Sclerosis: subependymal tubers, intraventricular giant cell astrocytomas, ependymomas
  結節性硬化症：室管膜下塊莖、腦室內巨細胞星形細胞瘤、室管膜瘤
• von Hippel Lindau: hemangioblastomas
  von Hippel Lindau：血管母細胞瘤

Many non-tumorous diseases like small vessel disease, infections (septic emboli, abscesses) or demyelinating diseases like MS can also present as multifocal disease.
許多非腫瘤性疾病，如小血管病、感染（膿毒性栓塞、膿腫）或脫髓鞘疾病（如 MS）也可能表現為多灶性疾病。

Cortical based tumors  皮質腫瘤

Most intra-axial tumors are located in the white matter.
大多數軸內腫瘤位於白質中。
Some tumors, however, spread to or are located in the gray matter.
然而，有些腫瘤會擴散到灰質或位於灰質中。
The differential diagnosis for these cortical based tumors includes oligodendroglioma, ganglioglioma and Dysembryoplastic Neuroepithial Tumor (DNET).
這些皮質腫瘤的鑒別診斷包括少突膠質細胞瘤、神經節膠質瘤和胚胎發育不良神經上瞼瘤 （DNET）。
A DNET is a rare benign neoplasm, usually in a cortical and temporal location.
DNET 是一種罕見的良性腫瘤，通常位於皮質和顳部位置。
Patients with a cortically based tumor usually present with complex seizures.
皮質腫瘤患者通常表現為複雜癲癇發作。

On the left a 45-year-old female with a stable seizure disorder (complex-partial) for 15 years.
左圖為一名 45 歲女性，患有穩定癲癇發作（複雜部分性）15年。
There is a non-enhancing, cortically based tumor.
有一個非增強的、基於皮質的腫瘤。
This is a ganglioglioma.  這是一種神經節膠質瘤。
The differential diagnosis includes DNET and pilocytic astrocytoma.
鑒別診斷包括 DNET 和毛細胞型星形細胞瘤。

These cortically based tumors have to be differentiated from non-tumorous lesions like cerebritis, herpes simplex encephalitis, infarction and post-ictal changes.
這些基於皮質的腫瘤必須與非腫瘤病變（如腦炎、單純皰疹性腦炎、梗塞和發作後變化）區分開來。

On the left are images of a 52-year-old female who, over the period of one year, complained of headache and neck pain.
左邊是一名 52 歲女性的照片，她在一年的時間里抱怨頭痛和頸部疼痛。
There is a recent onset of tonic-clonic seizures.
最近發作了強直陣攣性癲癇發作。
The CT shows a mass with calcifications, which extends all the way to the cortex.
CT 顯示一個帶有鈣化的腫塊，一直延伸到皮層。
Although this is a large tumor there is only limited mass effect on surrounding structures, which indicates that this is an infiltrating tumor.
雖然這是一個大腫瘤，但對周圍結構的佔位效應有限，這表明這是一個浸潤性腫瘤。
The most likely diagnosis is oligodendroglioma.
最可能的診斷是少突膠質細胞瘤。
The differential diagnosis includes a malignant astrocytoma or a glioblastoma.
鑒別診斷包括惡性星形細胞瘤或膠質母細胞瘤。

Fat - Calcification - Cyst - High density
脂肪 - 鈣化 - 囊腫 - 高密度

Fat has a low density on CT (- 100HU).
脂肪在 CT 上的密度較低 （- 100HU）。
On MR, fat has a high signal intensity on both T1- and T2WI.
在 MR 上，脂肪在 T1 和 T2WI 上都具有高信號強度。
On sequences with fat suppression fat can be differentiated from high signal caused by subacute hematoma, melanin, slow flow etc.
在具有脂肪抑製作用的序列上，脂肪可以與亞急性血腫、黑色素、慢血流等引起的高信號區分開來。
When you see high signal on T1WI always look for chemical shift artefact, as this indicates the presence of fat.
當您在 T1WI 上看到高信號時，請始終尋找化學位移偽影，因為這表明存在脂肪。
The chemical shift artefact occurs as alternating bands of high and low signal on the boundaries of a lesion and is seen only in the frequency encoding direction.
化學位移偽影表現為病變邊界上高信號和低信號的交替帶，並且僅在頻率編碼方向上可見。

Fat within a tumor is seen in lipomas, dermoid cysts and teratomas.
腫瘤內的脂肪可見於脂肪瘤、皮樣囊腫和畸胎瘤。
On the left a patient with the classical findings of a ruptured dermoid cyst.
左邊是具有皮樣囊腫破裂的典型表現的患者。

Some tumors can have a high density on CT.
一些腫瘤在 CT 上可能具有高密度。
This is typically seen in lymphoma, colloid cyst and PNET-MB (medulloblastoma).
這通常見於淋巴瘤、膠體囊腫和 PNET-MB（髓母細胞瘤）。

Calcification  鈣化

Calcification is seen in many CNS tumors (Table).
鈣化見於許多 CNS 腫瘤 （表）。
When we think of a calcified intra-axial tumor, we think oligodendroglioma since these tumors nearly always have calcifications.
當我們想到鈣化的軸內腫瘤時，我們會想到少突膠質細胞瘤，因為這些腫瘤幾乎總是有鈣化。
However an intraaxial calcified tumor in the brain is more likely to be an astrocytoma than a oligodendrogliomas, since astrocytomas, although less frequently calcified, are far more common.
然而，大腦中的軸內鈣化腫瘤比少突膠質細胞瘤更可能是星形細胞瘤，因為星形細胞瘤雖然鈣化較少，但更常見。
A pineocytoma itself does not calcify, but instead it 'explodes' the calcifications of the pineal gland.
松果細胞瘤本身不會鈣化，而是“爆炸”松果體的鈣化。

On the left is an image of a calcified mass in the suprasellar region, causing obstructive hydrocephalus.
左側是鞍上區鈣化腫塊的圖像，導致梗阻性腦積水。
This location in the suprasellar region and the calcification are typical for a craniopharyngioma.
這個位於蝶鞍上區的位置和鈣化是顱咽管瘤的典型特徵。
Craniopharyngiomas are slow growing, extra-axial, squamous epithelial, calcified, cystic tumors arising from remnants of Rathke's cleft.
顱咽管瘤是由Rathke裂隙殘餘物引起的生長緩慢的軸外鱗狀上皮狀、鈣化、囊性腫瘤。
They are located the (supra)sellar region and primarily seen in children with a small second peak incidence in older adults.
它們位於（上）鞍區，主要見於兒童，老年人的發病率呈較小的第二高峰。

On the left are images of a tumor with a small calcification. .
左側是帶有小鈣化的腫瘤圖像。.
The calcification is not appreciated on the MR images, but is easily seen on CT.
鈣化在 MR 圖像上看不清楚，但在 CT 上很容易看到。
The calcification and the extension of the tumor to the cortex are very typical for an oligodendroglioma.
鈣化和腫瘤向皮質的擴散是少突膠質細胞瘤非常典型的。
An astrocytoma should be in the differential.
星形細胞瘤應在鑒別診斷中。

On the left are images of a patient with progressive visual loss.
左側是進行性視力喪失患者的圖像。
On the coronal and sagittal TW1I there is a large mass centered around the sella with a broad dural base.
在冠狀面和矢狀面 TW1I 上，有一個以蝶鞍為中心的大腫塊，硬腦膜基底較寬。
There is extension into the sella.
有延伸到 sella。
This patient was booked for decompression.
該患者被預訂減壓。
Only after the CT was performed, was it appreciated how densely calcified this tumor is.
只有在進行 CT 后，人們才意識到這個腫瘤的鈣化密度有多大。
It would be impossible to operate this tumor and preserve the patient's vision.
不可能手術這個腫瘤並保留患者的視力。

Cystic versus Solid  囊性 vs 實性
There are many cystic lesions that can simulate a CNS tumor.
有許多囊性病變可以類比 CNS 腫瘤。
These include epidermoid, dermoid, arachnoid, neuroenteric and neuroglial cysts.
這些囊腫包括表皮樣囊腫、皮樣囊腫、蛛網膜囊腫、神經腸囊腫和神經膠質細胞囊腫。
Even enlarged perivascular spaces of Virchow Robin can simulate a tumor.
即使是 Virchow Robin 血管周圍擴大的間隙也可以模擬腫瘤。
In order to determine whether a lesion is a cyst or cystic mass look for the following characteristics:
為了確定病變是囊腫還是囊腫，請尋找以下特徵：

• Morphology   形態學
• Fluid/fluid level   流體/液位
• Content usually isointense to CSF on T1, T2 and FLAIR
  含量通常在 T1、T2 和 FLAIR 上與 CSF 等強度
• DWI: restricted diffusion
  DWI：擴散受限

An arachnoid cyst is isointense to CSF on all sequences.
蛛網膜囊腫在所有序列上都與 CSF 等信號。
Tumor necrosis may sometimes look like a cyst, but it is never completely isointense to CSF.
腫瘤壞死有時可能看起來像囊腫，但它從來都不是與 CSF 完全等信號的。

On the far left a craniopharyngioma with an enhancing rim surrounding the cystic component.
在最左側，顱咽管瘤在囊性成分周圍有一個增強的邊緣。
In the middle a neuroenteric cyst with the contents of which have the same signal intensity as CSF.
在中間，一個神經腸囊腫，其內容物與 CSF 具有相同的信號強度。
On the right a glioblastoma multiforme (GBM) with a central cystic component.
右側是具有中央囊性成分的多形性膠質母細胞瘤 （GBM）。
The enhancement in GBM is usually more irregular.
GBM 中的增強通常更不規則。

High on T1  T1 上的高電平

Most tumors have a low or intermediate signal intensity on T1WI.
大多數腫瘤在 T1WI 上具有低或中等信號強度。
Exceptions to this rule can indicate a specific type of tumor.
此規則的例外情況可能表示特定類型的腫瘤。
On the left is a list of causes for T1-shortening.
左側是 T1 期縮短的原因清單。
Calcifications are mostly dark on T1WI, but depending on the matrix of the calcifications they can sometimes be bright on T1.
鈣化在 T1WI 上大多是深色的，但根據鈣化的基質，它們有時在 T1 上可能是明亮的。
Especially on gradient echo images slow flow can be seen as bright signal on T1WI and should not be confused with enhancement.
特別是在梯度回波圖像上，慢速流動可以被視為 T1WI 上的明亮信號，不應與增強混淆。
This is particularly pronounced on gradient echo images.
這在漸變殘影圖像上尤其明顯。

If you only do an enhanced scan, remember that high signal is not always enhancement.
如果您只執行增強掃描，請記住，高信號並不總是增強。

On the left are some images of tumors with high signal intensities on T1WI.
左側是 T1WI 上具有高信號強度的腫瘤的一些圖像。
On the far left images of a patient who presented with apoplexy.
在最左側，一名出現中風的患者的圖像。
The high signal is due to hemorrhage in a pituitary macroadenoma.
高信號是由於垂體大腺瘤出血所致。
The patient in the middle has a glioblastoma multiforme, which caused a hemorrhage in the splenium of the corpus callosum.
中間的患者患有多形性膠質母細胞瘤，導致胼胝體脾出血。
On the right is a patient with a metastasis of a melanoma.
右邊是黑色素瘤轉移的患者。
The high signal intensity is due to the melanin content.
高信號強度是由於黑色素含量。

Low on T2  T2 低

Most tumors will be bright on T2WI due to a high water content.
由於含水量高，大多數腫瘤在 T2WI 上會很亮。
When tumors have a low water content they are very dense and hypercellular and the cells have a high nuclear-cytoplasmasmic ratio.
當腫瘤含水量低時，它們非常緻密且細胞增多，並且細胞具有較高的核質比率。
These tumors will be dark on T2WI.
這些腫瘤在 T2WI 上會變暗。
The classic examples are CNS lymphoma and PNET (also hyperdense on CT).
典型的例子是 CNS 淋巴瘤和 PNET（CT 上也很高）。
Calcifications are mostly dark on T2WI.
T2WI 上的鈣化大多是深色的。
The differential diagnosis of calcified tumors was discussed above.
鈣化腫瘤的鑒別診斷見上文。
Paramagnetic effects cause a signal drop and are seen in tumors that contain hemosiderin.
順磁效應會導致信號下降，可見於含有含鐵血黃素的腫瘤。
Proteinaceous material can be dark on T2 depending on the content of the protein itself.
蛋白質物質在 T2 上可能是深色的，具體取決於蛋白質本身的含量。
A classic example of this is the colloid cyst.
一個典型的例子是膠體囊腫。
Flow voids are also dark on T2 and indicate the presence of vessels or flow within a lesion.
T2 上的血流空隙也是深色的，表明病變內存在血管或血流。
This is seen in tumors that contain a lot of vessels like hemangioblastomas, but also in non-tumorous lesions like vascular malformations.
這見於包含大量血管的腫瘤（如血管母細胞瘤），但也見於非腫瘤病變（如血管畸形）。

On the left some examples of tumors with a low signal intensity on T2WI.
左邊是 T2WI 上信號強度低的一些腫瘤示例。

1. Melanoma metastases have a low SI on T2WI as a result of the melanin.
   由於黑色素，黑色素瘤轉移在T2WI上具有低SI。
2. GBM can have a low SI on T2WI because sometimes they have a high nuclear-cytoplasmic ratio. Most GBM's, however, are hyperintense on T2WI.
   GBM 在 T2WI 上的國際單位制可能較低，因為有時它們的核質比較高。然而，大多數 GBM 在 T2WI 上是高信號的。
3. PNET typically has a high nuclear-cytoplasmic ratio. PNET is mostly located in the region of the 4th ventricle, but another, less common, location is in the region of the pineal gland.
   PNET 通常具有較高的核質比值。PNET 主要位於第 4 腦室區域，但另一個不太常見的位置是在松果體區域。
4. Mucinous metastases can have a low SI on T2WI because they often contain calcifications..
   粘液性轉移瘤在T2WI上可能具有較低的SI，因為它們通常包含鈣化。
5. Meningiomas are mostly of intermediate signal.
   腦膜瘤多為中間信號。
   They can have a high SI on T2WI if they contain a lot of water.
   如果它們含有大量水，它們在T2WI上的國際單位制可能很高。
   They can have a low SI on T2WI if they are very dense and hypercellular or when they contain calcifications.
   如果它們非常緻密和細胞增多或含有鈣化，則它們在T2WI上的SI可能較低。

Diffusion weighted imaging
彌散加權成像

Normally water protons have the ability to diffuse extracellularly and loose signal.
通常，水質子具有在細胞外擴散和鬆散信號的能力。
High intensity on DWI indicates restriction of the ability of water protons to diffuse extracellularly.
DWI 的高強度表明水質子在細胞外擴散的能力受到限制。
Restricted diffusion is seen in abscesses, epidermoid cysts and acute infarction (due to cytotoxic edema).
彌散受限見於膿腫、表皮樣囊腫和急性梗死（由於細胞毒性水腫）。

In cerebral abscesses the diffusion is probably restricted due to the viscosity of pus, resulting in a high signal on DWI.
在腦膿腫中，由於膿液的粘度，擴散可能受到限制，導致 DWI 信號高。
In most tumors there is no restricted diffusion - even in necrotic or cystic components.
在大多數腫瘤中，沒有限制擴散 - 即使在壞死或囊性成分中也是如此。
This results in a normal, low signal on DWI.
這會導致 DWI 信號正常、低。

Perfusion Imaging  灌注成像

Perfusion imaging can play an important role in determining the malignancy grade of a CNS tumor.
灌注成像在確定 CNS 腫瘤的惡性腫瘤分級方面起著重要作用。
Perfusion depends on the vascularity of a tumor and is not dependent on the breakdown of the blood-brain barrier.
灌注取決於腫瘤的血管分佈，不依賴於血腦屏障的破壞。
The amount of perfusion shows a better correlation with the grade of malignancy of a tumor than the amount of contrast enhancement.
灌注量與造影劑增強量相比，與腫瘤惡性腫瘤分級的相關性更好。

Blood brain barrier  血腦屏障
The brain has a unique triple layered blood-brain barrier (BBB) with tight endothelial junctions in order to maintain a consistent internal milieu.
大腦具有獨特的三層血腦屏障 （BBB），具有緊密的內皮連接，以保持一致的內部環境。
Contrast will not leak into the brain unless this barrier is damaged.
除非這個屏障受損，否則造影劑不會洩漏到大腦中。
Enhancement is seen when a CNS tumor destroys the BBB.
當 CNS 腫瘤破壞 BBB 時，可以看到增強。

Extra-axial tumors such as meningiomas and schwannomas are not derived from brain cells and do not have a blood-brain barrier.
腦膜瘤和神經鞘瘤等軸外腫瘤不是來源於腦細胞，也沒有血腦屏障。
Therefore they will enhance.
因此，它們會增強。
There is also no blood-brain barrier in the pituitary, pineal and choroid plexus regions.
垂體、松果體和脈絡叢區域也沒有血腦屏障。

Some non-tumoral lesions enhance because they can also break down the BBB and may simulate a brain tumor.
一些非腫瘤病變增強，因為它們也可以分解 BBB 並可能類比腦腫瘤。
These lesions include like infections, demyelinating diseases (MS) and infarctions.
這些病變包括感染、脫髓鞘疾病 （MS） 和梗塞。

Contrast enhancement cannot visualize the full extent of a tumor in cases of infiltrating tumors, like gliomas.
在浸潤性腫瘤（如神經膠質瘤）的情況下，造影劑增強無法顯示腫瘤的全部範圍。
The reason for this is that tumor cells blend with the normal brain parenchyma where the blood brain barrier is still intact.
原因是腫瘤細胞與血腦屏障仍然完整的正常腦實質混合。
Tumor cells can be found beyond the enhancing margins of the tumor and beyond any MR signal alteration - even beyond the area of edema.
腫瘤細胞可以在腫瘤的增強邊緣之外和任何 MR 信號改變之外找到 - 甚至超出水腫區域。

On the left is an image of a 42 y/o male with mild head trauma.
左邊是一名 42 歲男性的照片，患有輕度頭部外傷。
On the T2WI there is a lesion in the left temporal lobe, found incidentally.
在 T2WI 上，左顳葉有一個病變，是偶然發現的。
There was no enhancement and the DWI was normal.
沒有增強，DWI 正常。
During follow-up there was a slight increase in size.
在隨訪期間，大小略有增加。
This was diagnosed as a low-grade astrocytoma.
這被診斷為低級別星形細胞瘤。
It is not possible to resect such a lesion, since the infiltrating tumors cells are within the normal-appearing brain tissue.
無法切除這樣的病變，因為浸潤的腫瘤細胞位於外觀正常的腦組織內。

In gliomas - like astrocytomas, oligodendrogliomas and glioblastoma multiforme - enhancement usually indicates a higher degree of malignancy.
在神經膠質瘤中 - 如星形細胞瘤、少突膠質細胞瘤和多形性膠質母細胞瘤 - 增強通常表明惡性程度較高。
Therefore when during the follow up of a low-grade glioma the tumor starts to enhance, it is a sign of malignant transformation..
因此，當低級別神經膠質瘤的隨訪過程中，腫瘤開始增強時，這是惡性轉化的跡象。
Gangliogliomas and pilocytic astrocytomas are the exceptions to this rule: they are low-grade tumors, but they enhance vividly.
神經節膠質瘤和毛細胞星形細胞瘤是這一規則的例外：它們是低級別腫瘤，但它們的增強非常明顯。

As discussed above, it recently has been shown that tumor angiogenesis as shown by perfusion MR correlates better with tumor grade than enhancement after the administration of intravenous contrast.
如上所述，最近已經表明，灌注 MR 顯示的腫瘤血管生成與腫瘤分級的相關性優於靜脈注射造影劑后增強的相關性。

The amount of enhancement depends on the amount of contrast that is delivered to the interstitium.
增強量取決於傳遞到間質的對比度量。
In general, the longer we wait, the better the interstitial enhancement will be.
一般來說，我們等待的時間越長，間隙增強效果就越好。
The optimal timing is about 30 minutes and it is better to give contrast at the start of the examination and to do the enhanced T1WI at the end.
最佳時間約為 30 分鐘，最好在檢查開始時提供造影劑，並在結束時進行增強的 T1WI。

No enhancement is seen in:
在以下方面未看到增強：

• Low grade astrocytomas   低級別星形細胞瘤
• Cystic non-tumoral lesions:
  囊性非腫瘤病變：
  • Dermoid cyst   皮樣囊腫
  • Epidermoid cyst   表皮樣囊腫
  • Arachnoid cyst   蛛網膜囊腫

On the left is an image of an intra-axial tumor in an adult.
左側是成人軸內腫瘤的圖像。
It is centered in the temporal lobe and involves the cortex.
它以顳葉為中心，涉及皮層。
Although there is massive infiltrative growth involving a large part of the right cerebral hemisphere, there is only minimal mass effect.
儘管存在涉及右大腦半球大部分的大量浸潤性生長，但只有極小的佔位效應。
There is no enhancement.  沒有增強。
These features are typical for a low-grade astrocytoma.
這些特徵是低級別星形細胞瘤的典型特徵。

Homogeneous enhancement can be seen in:
同質增強可見於：

• Metastases   轉移
• Lymphoma   淋巴瘤
• Germinoma and other pineal gland tumors
  生殖細胞瘤和其他松果體腫瘤
• Pituitary macroadenoma   垂體大腺瘤
• Pilocytic astrocytoma and hemangioblastoma (only the solid component)
  毛細胞型星形細胞瘤和血管母細胞瘤（僅實體成分）
• Ganglioglioma   神經節膠質瘤
• Meningioma and Schwannoma
  腦膜瘤和神經鞘瘤

Patchy enhancement can be seen in:
斑塊狀增強可見於：

• Metastases   轉移
• Oligodendroglioma   少突膠質細胞瘤
• Glioblastoma multiforme   多形性膠質母細胞瘤
• Radiation necrosis   放射性壞死

On the left is an example of a glioblastoma multiforme (GBM).
左邊是多形性膠質母細胞瘤 （GBM） 的示例。
The enhancement indicates that this is a high-grade tumor, but only parts of it enhance.
增強表明這是一種高級別腫瘤，但只有部分增強。
Notice that there is also a cystic component with ring enhancement.
請注意，還有一個具有環增強的囊性成分。
The tumor cells probably extend beyond the area of edema as seen on the FLAIR image.
腫瘤細胞可能延伸到 FLAIR 圖像上看到的水腫區域之外。
This is because gliomas grow infiltratively into normal brain - initially without any MR changes.
這是因為神經膠質瘤浸潤性地生長到正常的大腦中 - 最初沒有任何 MR 變化。

Patchy enhancement (2)  斑駁增強 （2）
On the left are images of a tumor located in the right hemisphere.
左側是位於右半球的腫瘤圖像。
Although is a large tumor, the mass-effect is limited.
雖然是一個大腫瘤，但佔位效應是有限的。
This indicates that there is marked infiltrative growth, a characteristic typical for gliomas.
這表明有明顯的浸潤性生長，這是神經膠質瘤的典型特徵。
Notice the heterogeneity on both T2WI and FLAIR.
請注意 T2WI 和 FLAIR 上的異構性。
There is patchy enhancement.
有零星的增強。
All these findings are typical for a GBM.
所有這些發現都是 GBM 的典型表現。
Virtually no other tumor behaves in this way.
幾乎沒有其他腫瘤以這種方式表現。

Ring enhancement  戒指增強
Ring enhancement is seen in metastases and high-grade gliomas.
環增強見於轉移瘤和高級別膠質瘤。
It is also seen in non-tumorous lesions like abscesses, some MS-plaques and sometimes in an old hematomas.
它也見於非腫瘤病變，如膿腫、一些 MS 斑塊，有時也見於陳舊的血腫。

On the left three different ring enhancing lesions.
左側是三個不同的環狀增強病變。

Conspicuity of tumors with contrast
增強腫瘤的顯著性

The case on the left demonstrates the value of Gadolinium in the conspicuity of tumors.
左邊的案例證明瞭釙在腫瘤顯眼方面的價值。
This is a patient with Neurofibromatosis II.
這是一名患有II型神經纖維瘤病的患者。
After the administration of contrast the two meningiomas and the schwannoma are easily seen.
造影劑給葯后，很容易看到兩個腦膜瘤和神經鞘瘤。

Leptomeningeal metastases are usually not seen without the administration of intravenous contrast.
如果不靜脈注射造影劑，通常看不到軟腦膜轉移。
The case on the left demonstrates the abnormal enhancement along the brainstem, along the folia of the cerebellum (yellow arrow) and along the fifth intracranial nerve (blue arrow) in a patient with leptomeningeal metastases.
左側的病例顯示了軟腦膜轉移患者沿腦幹、小腦葉（黃色箭頭）和沿顱內第五神經（藍色箭頭）的異常增強。

Skull base  顱

Common skull base tumors are listed in the table on the left.
常見的顱底腫瘤列在左表中。
These tumors either arise from extracranial structures like the sinuses (sinonasal carcinoma), or from the skull base itself (chordoma, chondrosarcoma, fibrous dysplasia).
這些腫瘤要麼起源於鼻竇等顱外結構（鼻竇癌），要麼起源於顱底本身（脊索瘤、軟骨肉瘤、纖維發育不良）。
Chordoma is usually located in the midline, while chondrasarcoma usually arises off the midline.
脊索瘤通常位於中線，而軟骨肉瘤通常出現在中線外。

On the left a midline tumor arising from the clivus.
左側是起源於的中線腫瘤。
This is the typical presentation of a chordoma.
這是脊索瘤的典型表現。
The differential diagnosis would include a metastasis and a chondrosarcoma.
鑒別診斷將包括轉移和軟骨肉瘤。

On the left another skull base tumor located off midline.
左側是另一個位於中線外的顱底腫瘤。
This is a typical presentation for a chondrosarcoma.
這是軟骨肉瘤的典型表現。
The differential diagnosis would include a metastasis and a paraganglioma.
鑒別診斷將包括轉移和副神經節瘤。
Chondrosarcomas can be located in the midline and chordomas are sometimes located off midline but those cases are exceptional.
軟骨肉瘤可以位於中線，而脊索瘤有時位於中線之外，但這些情況是例外。

On the left an example of a Skull Base Paraganglioma.
左邊是顱底副神經節瘤的例子。

On the left CT images of a 58-year-old male with a gradual onset of right facial pain and numbness and a recent onset of double vision.
左側 CT 圖像顯示一名 58 歲男性，右側面部疼痛和麻木逐漸發作，近期出現複視。
First study the images, than continue.
先研究圖像，然後再繼續。

There is an enhancing mass anterior to the skull base and also in the region of the right cavernous sinus.
在顱底前方和右海綿竇區域有一個增強的腫塊。
In the bone window setting there is sclerosis of the skull base, particularly in the region of the clivus.
在骨窗設置中，顱底硬化，尤其是在區域。
Continue with the MR images.
繼續使用 MR 映像。

On the left enhanced sagittal and coronal T1WI.
左側增強矢狀面和冠狀面 T1WI。
The most striking finding is the black clivus due to the sclerosis.
最引人注目的發現是由於硬化引起的黑色。
A normal clivus is bright on T1WI as a result of the fatty bone marrow.
由於脂肪骨髓，正常的在 T1WI 上是明亮的。
There is an enhancing mass anterior to the clivus.
前有一個增強的腫塊。
On the coronal images we see the enhancement extending through the foramen ovale to the right of the cavernous sinus.
在冠狀圖像上，我們看到增強從卵圓孔延伸到海綿竇的右側。
The diagnosis is a nasopharyngeal squamous cell carcinoma with intracranial extension.
診斷為鼻咽鱗狀細胞癌伴顱內擴散。
The differential diagnosis would include: skull base metastasis, lymphoma, chronic infection and even a meningioma - although this would be an unusual way for a meningioma to spread.
鑒別診斷包括：顱底轉移、淋巴瘤、慢性感染甚至腦膜瘤 - 儘管這是腦膜瘤不尋常的擴散方式。

Sella/suprasellar  鞍形/外密封

On the left is a list of common sellar and suprasellar tumors.
左側是常見的鞍區和鞍上腫瘤清單。
In this region it is important to keep the possibility of an aneurysm in the differential diagnosis.
在這個區域，在鑒別診斷中保留動脈瘤的可能性很重要。

On the left are images of a mass in the suprasellar cistern.
左側是鞍上池中腫塊的圖像。
On the NECT we can see that it contains calcium.
在 NECT 上，我們可以看到它含有鈣。
On the T1WI there is a hyperintense area that shows no enhancement (i.e. cystic).
在 T1WI 上有一個高信號區域，沒有顯示增強（即 囊性）。
There are other components that show enhancement.
還有其他元件顯示增強功能。
The tumor is complicated by a hydrocephalus.
腫瘤併發腦積水。
These findings are very specific for a craniopharyngeoma.
這些發現對於顱咽瘤非常具有特異性。

On the left NECT and enhanced CT-images of a 33-year-old female with severe headache (worse in the a.m.), reduction in visual acuity and visual fields and papilledema.
左側為一名 33 歲女性的 NECT 和增強 CT 圖像，患者患有嚴重頭痛（早上加重），視力和視野下降以及視水腫。
Continue with the MR images.
繼續使用 MR 映像。

Notice the normal inferiorly displaced pituitary gland.
注意正常下移位的垂體。
This means it is not a macroadenoma.
這意味著它不是大腺瘤。
The diagnosis is again a craniopharyngioma.
診斷又是顱咽管瘤。
The differential diagnosis would include an astrocytoma and a meningioma.
鑒別診斷包括星形細胞瘤和腦膜瘤。

Cerebello-pontine angle  小腦橋角

Common CP Angle Tumors are listed in the table on the left.
常見的 CP 角腫瘤列在左表中。

On the left a 52-year-old male with hearing loss on the right.
左邊是 52 歲的聽力損失男性，右邊。
The images show an unusual cystic mass with enhancing septations.
圖像顯示一個不尋常的囊性腫塊，間隔增強。
There is also some enhancement within the internal acoustic canal.
內部聲道內也有一些增強。
Based on the images the most likely diagnosis would be a cystic schwannoma, but this happened to be an uncommon, cystic presentation of a meningioma.
根據圖像，最可能的診斷是囊性神經鞘瘤，但這恰好是腦膜瘤的罕見囊性表現。

Pineal region

Common pineal region tumors are listed in the table on the left.

On the left a tumor located in the pineal region.

Based on these images the differential diagnosis would include:

• Meningioma
• Pineocytoma
• Germ Cell Tumor

This happened to be a meningioma.

On the left are typical images of a ruptured pineal region dermoid.

On the left images of a 12 y/o male with upward gaze paralysis.
There is a tumor located in the pineal region.
The tumor contains calcifications.
There is homogeneous enhancement, which is common for a tumor in the pineal region (discussed above).
Based on the age of the patient, the location and the tumor characteristics, this is most likely a germinoma.

Intraventricular

Common intraventricular Tumors are listed in the table on the left.

On the left a tumor located in the 3rd ventricle.
The tumor contains calcifications.
The diagnosis is a giant cell astrocytoma.

4th ventricle

In children tumors in the 4th ventricle are very common.
Astrocytomas are the most common followed by medulloblastomas (or PNET-MB), ependymomas and brainstem gliomas with a dorsal exophytic component.

In adults tumors in the 4th ventricle are uncommon.
Metastases are most frequently seen, followed by hemangioblastomas, choroid plexus papillomas and dermoid and epidermoid cysts.

Many non-tumorous lesions can mimic a brain tumor.
Abscesses can mimic metastases.
Multiple sclerosis can present with a mass-like lesion with enhancement, also known as tumefactive multiple sclerosis..
In the parasellar region one should always consider the possibility of a aneurysm.

Infections and vascular lesions can also mimic a CNS tumor.

Charity

All the profits of the Radiology Assistant go to Medical Action Myanmar which is run by Dr. Nini Tun and Dr. Frank Smithuis sr, who is a professor at Oxford university and happens to be the brother of Robin Smithuis.

Click on the image below to watch the video of Medical Action Myanmar and if you like the Radiology Assistant, please support Medical Action Myanmar with a small gift.