CT to assess lumbar fusion integrity

[NJPAIN]

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I am not a radiologist but rather an interventional pain physician. I see more than just a few patients > 1 year post lumbar interbody fusion with persistent axial low back pain. While there can obviously be a number of reasons for this situation, one potential cause is pseudoarthrosis. In such cases, while I am aware that no imaging modality is definitive, I order the "gold-standard" CT scan. From a radiology article from a few years back I use the following:

Dx: S/P Lumbar interbody fusion @

Patient orientation Supine, feet first
Gantry tilt 0°
Region of interest Initial exam: mid-T12 to mid-sacrum

Kernel/algorithm B80/bone
Milliamperage (mA) 250
Kilovoltage (kV) 140
Field of view (FOV) 14 cm
Matrix 512 × 512
Volume acquisition slice collimation 1.0 mm
Image reconstruction progression
Step 1 Reconstructed axial 3.0-mm-thick sections; entire scan volume
Step 2 Reconstructed axial 1.0-mm-thick sections at 0.5-mm increments (overlapped); region of interest only
Step 3 Reformatted images in 3 planes; region of interest; 1.0 mm axial (parallel to the disc); 3.0 mm coronal and sagittal
Window and level settings 2000–3000/350–400

***PLEASE EVALUATE FOR FUSION PROGRESSION AND EVIDENCE OF PSEUDOARTHOSIS***

What I inevitably receive is a report commenting on the adjacent levels and the position of the hardware but no comment on graft consolidation, etc that would help make a conclusion regarding pseudoarthrosis.

My question to all of you is two-fold:
1. Is the above imaging protocol out-dated?
2. Is it reasonable to ask a radiologist to comment on the integrity of the fusion or is the expectation that the ordering physician will make that determination upon reviewing the imaging themselves? If this is a reasonable expectation how to I get a radiologist to give me the info that I need? If not, please point me toward info I can use to educate myself to make that interpretation.

 

[scootad.]

For something specific like that, its a good idea to get on the phone with the radiologist(s) at the facility you refer your patients to and tell them specifically what you want commented on. Generally speaking, your case ends up being added to a list of 100+ cases on our list on any given day, and we have a hell of a time getting through the case quickly/efficiently while commenting on the DDD happening above and below the fusion, rather than talking about how well the fusion is progressing. That is a detail that gets pushed to the side. Get on the phone with your radiologists and tell them what you want.

 

[shark2000]

I am not a radiologist but rather an interventional pain physician. I see more than just a few patients > 1 year post lumbar interbody fusion with persistent axial low back pain. While there can obviously be a number of reasons for this situation, one potential cause is pseudoarthrosis. In such cases, while I am aware that no imaging modality is definitive, I order the "gold-standard" CT scan. From a radiology article from a few years back I use the following:

Dx: S/P Lumbar interbody fusion @

Patient orientation Supine, feet first
Gantry tilt 0°
Region of interest Initial exam: mid-T12 to mid-sacrum

Kernel/algorithm B80/bone
Milliamperage (mA) 250
Kilovoltage (kV) 140
Field of view (FOV) 14 cm
Matrix 512 × 512
Volume acquisition slice collimation 1.0 mm
Image reconstruction progression
Step 1 Reconstructed axial 3.0-mm-thick sections; entire scan volume
Step 2 Reconstructed axial 1.0-mm-thick sections at 0.5-mm increments (overlapped); region of interest only
Step 3 Reformatted images in 3 planes; region of interest; 1.0 mm axial (parallel to the disc); 3.0 mm coronal and sagittal
Window and level settings 2000–3000/350–400

***PLEASE EVALUATE FOR FUSION PROGRESSION AND EVIDENCE OF PSEUDOARTHOSIS***

What I inevitably receive is a report commenting on the adjacent levels and the position of the hardware but no comment on graft consolidation, etc that would help make a conclusion regarding pseudoarthrosis.

My question to all of you is two-fold:
1. Is the above imaging protocol out-dated?
2. Is it reasonable to ask a radiologist to comment on the integrity of the fusion or is the expectation that the ordering physician will make that determination upon reviewing the imaging themselves? If this is a reasonable expectation how to I get a radiologist to give me the info that I need? If not, please point me toward info I can use to educate myself to make that interpretation.

1- The protocol sounds good. Sagittal reconstruction is the key. Coronal can be helpful.

2- Yes definitely. Doing CT on a postop patient may have two indications:
a- From ED because the patient had a trauma.
b- For hardware evaluation.

If you order a CT in a patient with hardware, the radiologist should comment on the hardware. Some basics are the integrity of the hardware, lucency or cystic changes around the transpedicular screws (indicate loosening), any sign of possible infection and the osseous bridging/fusion.

Because of metal artifact MRI sucks. CT is the MOC for evaluation of hardware. Some places mostly academic places may do SPECT-CT. For something like pseudoarthrosis it can help since you have both the CT and the SPECT data. Also if the patient has persistent pain, you will be able to find the level with the most inflammation (for example a facet joint above the level of hardware) and inject here. Also since pseudoarthrosis has motion, it can help.

Plain films can be very very useful at times. In fact, this is one of the only times that I recommend plain films for evaluation of spine. Do flexion, neutral and extension views. It can assess the dynamic stability of the spine, something that other modalities can not check (Unless you do some fancy research MRI) and is cheap. I have seen a few cases that plain films were more useful than CT.

Having said that, spine imaging is considered very boring to many radiologists probably just second to mammo. As a result, there are a lot of not so useful reports out there. Also most spine imaging these days are orders by PAs or PCPs. I agree with the above poster. Talk to the radiologist and let him know that what you are looking for and what you want to be in the report. Otherwise, he may think you just ordered the study without knowing the reason (common scenario these days).

 

[DrBowtie]

Thirded that you call the radiologist, tell him what you want and figure out what to write in indication to make sure it's reproducible. Possibly get the study routed to the same guy you talked to each time.

 

[meister]

It's funny you specifically ask them to comment on the fusion and look for pseudoarthrosis and it gets ignored. I would talk to a local group and tell them what you want looked at and maybe you could get some decent information via changing their reporting habits/protocols as a group. It's unreasonable to ask you to call the radiologist every time.

 

[NJPAIN]

Thank you ALL for the information. I must say that I agree with the last post. It is unreasonable to expect that I have to call a radiologist to tell him/her what is in writing on the requisition. The biggest question in my mind was - are they not answering my question because they don't know how to?

 

[NJPAIN]

Just to follow up. I spoke with the administrator at the large radiology practice regarding my disappointment with the report received when I requested information regarding the integrity of a PLIF. I asked how we could resolve this now and in the future. Two days later I received an addendum to the original CT report that stated " no evidence of pseudoarthrosis".

 

[DrBowtie]

Just to follow up. I spoke with the administrator at the large radiology practice regarding my disappointment with the report received when I requested information regarding the integrity of a PLIF. I asked how we could resolve this now and in the future. Two days later I received an addendum to the original CT report that stated " no evidence of pseudoarthrosis".

The problem is that you spoke with the administrator. Doc to Doc with the neuro radiologists would likely lead to more fruitful change. I hope they elevate to the level of service you want or send your business elsewhere.