However, twinkling artifact is prone to false-positives, with a false- positive rate reported up to 60% [41]. Also, the performance of color Doppler is influenced by stone site and diameter [42]. It should be noted that the targeted use of Doppler for nonvascular assessment does not constitute a full Doppler examination. US can also be combined with radiography to improve stone detection and has been pursued as an alternative to CT, particularly for the detection of clinically significant stones. In a prospective study of 66 patients, the combination of US and radiography demonstrated a sensitivity of 79% (versus 93% for noncontrast CT) for detecting stones. However, in this series, all missed cases had spontaneous stone passage, in which case noncontrast CT may not have added useful information [37]. In a more recent study, the combination of US and radiography yielded a sensitivity of 90% and specificity of 68%, with decreased detection rates for stones <5 mm [30]. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature documenting the additional benefit of repeat noncontrast CT followed by CT abdomen and pelvis with IV contrast in a patient with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. CT Abdomen and Pelvis Without IV Contrast The patient with known current stone disease, diagnosed on recent imaging, with recurrent symptoms of stone disease is more likely to have urolithiasis as the etiology of flank pain than other etiologies. As such, it is important to assess if symptoms are related to interval stone migration or passage as opposed to complications of urolithiasis such as infection, perinephric abscess, urinoma, etc. Similar to Variant 1, noncontrast CT is currently considered the reference standard for the evaluation of urolithiasis, with a reported sensitivity as high as 97% [15,16].
Acute Onset Flank Pain Suspicion of Stone Disease Urolithiasis . However, twinkling artifact is prone to false-positives, with a false- positive rate reported up to 60% [41]. Also, the performance of color Doppler is influenced by stone site and diameter [42]. It should be noted that the targeted use of Doppler for nonvascular assessment does not constitute a full Doppler examination. US can also be combined with radiography to improve stone detection and has been pursued as an alternative to CT, particularly for the detection of clinically significant stones. In a prospective study of 66 patients, the combination of US and radiography demonstrated a sensitivity of 79% (versus 93% for noncontrast CT) for detecting stones. However, in this series, all missed cases had spontaneous stone passage, in which case noncontrast CT may not have added useful information [37]. In a more recent study, the combination of US and radiography yielded a sensitivity of 90% and specificity of 68%, with decreased detection rates for stones <5 mm [30]. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature documenting the additional benefit of repeat noncontrast CT followed by CT abdomen and pelvis with IV contrast in a patient with known current stone disease, diagnosed on recent imaging with recurrent symptoms of stone disease. CT Abdomen and Pelvis Without IV Contrast The patient with known current stone disease, diagnosed on recent imaging, with recurrent symptoms of stone disease is more likely to have urolithiasis as the etiology of flank pain than other etiologies. As such, it is important to assess if symptoms are related to interval stone migration or passage as opposed to complications of urolithiasis such as infection, perinephric abscess, urinoma, etc. Similar to Variant 1, noncontrast CT is currently considered the reference standard for the evaluation of urolithiasis, with a reported sensitivity as high as 97% [15,16].