CT/Ultrasound Contradiction

Hi there, I have a question about a patient I have that I am hoping someone with more experience might have seen before. So this patient (post op) I have has an enterobacter infection that has formed abscesses in the abdominal cavity,this is being treated by a cocktail of antibiotics. Two weeks ago this patient had a CT scan to check for a bleed due to low hemoglobin. This patient had a CT about 2 weeks after the first one and the liver shows multiple lesions on the liver that weren't there 2 weeks ago on the first CT. One doctor thinks it could be cancerous and one says more likely abscesses. So they sent this patient for an Ultrasound to attempt to biopsy, however they could not find the lesions on the ultrasound. This seems so weird to me, has anyone seen a contradiction between the ultrasound and CT exams? Also, if this is cancer- has anyone heard of lesions popping up this quickly. This specific patient really interests me.

Thanks in advance for your expertise
Abscesses could, fer sher.

I can't speak to the contradicting findings between the ultrasound and the CT but I have seen contradictions in other studies... CTs that were negative while the MRI revealed a tumor, for example. Certain scans are more sensitive to certain findings.As far as cancer happening that quickly, yes, have seen that... once had a child who was s/p gross total resection of a malignant brain tumor. She did well post-operatively, was discharged home and returned with symptoms of hydrocephalus. She went to the ER for a shunt placement and had scans immediately thereafter. Neither the scans before surgery nor the ones immediately thereafter showed any evidence of tumor. Less than 48 hours later, follow up scans showed her cancer was back and spreading rapidly. With aggressive cancers that are not being treated, there most certainly will be changes in imaging over a short period of time.

They should have used the CT to do the biopsy. Ultrasound is just sonar waves sent through an area and what comes back as a pic is whatever structures the waves bounce off. If US doesn't pick it up then CT would be the best option.....or fluoroscope