Hi Deepak,
welcome to our forum and thank you very much for your interest in our data converters.
First of all I will probably have to disappoint you. There is no way you can achieve a noise free resolution (and especially not an accuracy) of 0.0001°C with a Pt500/1000 and a 24bit ADC.
Customers typically achieve resolutions in the 0.01°C range and accuracies in the 0.05°C range using data converters such as the ADS1248. Theoretically resolutions of 0.001°C might be possible.
We have two very good application notes that talk about how a setup for a Pt1000 measurement should look like and how you should set up the external filters:
http://www.ti.com/litv/pdf/sbaa201
http://www.ti.com/litv/pdf/sbaa180
The ADS1248 offers integrated current sources and a PGA. So you don't need to build them yourself externally. Appart from the RC-filters and a reference resistor RREF there is not much more that you will need to implement the measurement.
Depending on the temperature range you need to cover you need to find the sweet spot for the IDAC, RREF and PGA setting.
I guess your current will end up in the 100uA to 250uA range with a gain of 4,8 or 16V/V.
Regards,