Dear Feng,
On 3 Apr 2017, at 10:17, FENG LIU wrote:
> Thanks a lot, Christian
>
> You mean that I can directly use the Jacobian Determinant images to
> conduct
> between-group statistical analysis, and this is actually the TBM
> analysis
> in the previous studies, right?
Yes.
>
> By the way, I notice that both VBM8 and CAT12 can generate the
> Jacobian
> Determinant images, so I can use either of them, correct?
I would recommend the newer version CAT12…
Best,
Christian
>
> Best,
> Feng
>
> On Mon, Apr 3, 2017 at 2:10 PM, Christian Gaser
> <[log in to unmask]
>> wrote:
>
>> Dear Feng,
>>
>> in CAT12 this is not possible. It only provides the Jacobian
>> Determinant,
>> which expresses the local volume changes, which might be sufficient
>> for
>> most morphometric analyses.
>>
>> Best,
>>
>> Christian
>>
>> On Sun, 2 Apr 2017 19:24:01 +0800, FENG LIU <[log in to unmask]>
>> wrote:
>>
>>> Thanks a lot, Xiaowei
>>>
>>> But the CAT12 toolbox just generate the Jacobian determinant images
>>> rather
>>> than Jacobian matrix.
>>>
>>> Anyone knows how to obtain the Jacobian matrix?
>>>
>>> Best,
>>> Feng
>>>
>>> On Wed, Mar 29, 2017 at 10:15 PM, Xiaowei Song
>>> <[log in to unmask]>
>>> wrote:
>>>
>>>> Hi, Feng,
>>>>
>>>> From the text you attached, it already answered your question as:
>>>>
>>>>> According to the polar decomposition
>>>>> theorem [21], a non-singular Jacobian matrix can be decomposed
>>>>> into a
>>>>> rotation matrix (R)
>>>>> and a symmetric positive definite matrix (U or V), such that J =
>>>>> RU =
>> VR.
>>>>
>>>>
>>>> In practice, if you decompose your J by using QR, the U or V as
>>>> referred
>>>> above should represent only shape change, i.e., discarding Q since
>>>> it
>>>> encodes orientation.
>>>>
>>>> Please fix me if I am wrong.
>>>>
>>>> Best,
>>>> Xiaowei Song
>>>>
>>>>
>>>> On Wed, Mar 29, 2017 at 3:24 AM, FENG LIU <[log in to unmask]>
>> wrote:
>>>>
>>>>> Dear CAT and SPM experts,
>>>>>
>>>>> I have a question about the TBM analysis.
>>>>>
>>>>> Now I have obtained the Jacobian determinant images by using the
>>>>> CAT12
>>>>> toolbox. Could I directly use these images to perform a TBM
>>>>> analysis?
>>>>>
>>>>> In the last paragraph of page 10 (attached), it wrote "Because a
>> Jacobian
>>>>> matrix encodes both local shape (zooms and shears) and
>>>>> orientation, it
>> is
>>>>> necessary to remove the latter before making inferences." So, how
>> should I
>>>>> do in a right way?
>>>>>
>>>>> Any help would be greatly appreciate.
>>>>>
>>>>> Best,
>>>>> Feng
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Xiaowei Song
>>>>
>>>
>>
>>
>>
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