CT fluoroscopy-guided vs. multislice CT biopsy mode-guided lung biopsies: Accuracy, complications and radiation dose

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Abstract

Background

The aim of this retrospective study was to compare the diagnostic accuracy, the frequency of complications, the duration of the interventions and the radiation doses of CT fluoroscopy (CTF) guided biopsies of lung lesions with those of multislice CT (MS-CT) biopsy mode-guided biopsies.

Methods

Data and images from 124 consecutive patients undergoing CTF-guided lung biopsy (group A) and 132 MS-CT-biopsy mode-guided lung biopsy (group B) were reviewed. CTF-guided biopsies were performed on a Siemens Emotion 6 CT scanner with intermittent or continuous CT-fluoroscopy, MS-CT biopsy mode-guided biopsies were performed on a Siemens Emotion 16 CT scanner. All biopsies were performed with a coaxial needle technique.

Results

The two groups (A vs. B) did not differ significantly regarding sensitivity (95.5% vs. 95.9%), specificity (96.7% vs. 95.5%), negative predictive value (87.9% vs. 84%) or positive predictive value (98.8% vs. 98.9%). Pneumothorax was observed in 30.0% and 32.5% of the patients, respectively. Chest tube placement was necessary in 4% (group A) and 13% (group B) of the patients. The duration of the intervention was significantly longer in group A (median 37 min vs. 32 min, p = 0.04). The mean CT dose index (CTDI) was 422 in group A and 36.3 in group B (p < 0.001).

Conclusion

Compared to CTF-guided biopsies, chest biopsies using the MS-CT biopsy mode show dramatically lower CTDI levels. Although the diagnostic yield of the procedures do not differ significantly, biopsies using the MS-CT-biopsy mode have a three-fold higher rate of chest tube placement.

Introduction

Percutaneous CT-guided biopsy of pulmonary nodules has been shown to be an accurate and safe procedure for making a tissue diagnosis of lung lesions. To achieve optimal biopsy results, reliable verification of the needle position throughout the intervention is essential. Traditionally, the needle position is verified by performing intermittent spiral CT scans or by CT fluoroscopy (CTF).

Intermittent spiral CT scans are usually limited to the region of the biopsy and may or may not be performed using a low-dose technique. While performing intermittent spiral CT scans, the personnel performing the intervention leave the CT room and are thus not exposed to radiation.

In contrast to intermittent spiral CT scans, CTF allows real-time guidance of the needle to the pulmonary nodule and is reported to be performed with a high diagnostic yield [1], [2], [3], [4], [5]. In CTF guided biopsies, the radiologist performing the intervention is provided with real-time images, which allow a continuous visualization of the needle position. Compared to intermittent CT scans, the intervention time in CTF-guided biopsies is shorter, as the radiologist performing the intervention does not leave the CT room while controlling the needle position. CTF-guided biopsies, however, are reported to be associated with a substantial radiation exposure to patients and personnel [6], [7]. The relatively high radiation doses in CTF guided biopsies can be attributed to the fact, that the patient is exposed to ionizing radiation as long as the radiologist is pressing the foot pedal. The radiation dose to the personnel is of particular concern if one of the hands of the radiologist is within the radiation beam during the intervention [8].

Newer generations of multislice CT (MS-CT) scanners are equipped with biopsy software packages that allow the acquisition and display of three or more slices in one rotation of the scanner (MS-CT biopsy mode, Fig. 1). By pressing the foot pedal next to the patient, the radiologist performing the intervention can immediately obtain three contiguous slices, which allows verification of the needle position and correction of the position, if necessary. Compared to CTF, MS-CT biopsy mode-guided biopsies may be performed with significantly lower radiation doses.

The aim of our study was to compare CTF-guided with MS-CT biopsy mode-guided biopsies with regard to the diagnostic accuracy, frequency of complications, duration of the intervention and radiation dose.

Section snippets

Materials and methods

In this retrospective study, we reviewed the data of CTF-guided lung biopsies performed between November 1st 2004 and January 31st 2007 using a 6-slice CT scanner (Siemens Emotion 6, Siemens Medical Solutions, Forchheim, Germany) and of MS-CT-biopsy mode-guided lung biopsies performed between February 1st 2007 and June 1st 2008 using a 16-slice CT scanner (Siemens Emotion 16, Siemens Medical Solutions, Forchheim, Germany). This sequential investigation of CTF-guided biopsies and MS-CT biopsy

Results

The demographic data of the patient populations and lesion characteristics are summarized in Table 1. The two groups were comparable, as they did not differ significantly regarding the age and sex of the patients. Also, the lesions of the two groups did not differ significantly regarding the final diagnoses, size, depth and location.

The slice thickness in group A was 10 mm in 77 biopsies, 6 mm in 13 biopsies and 4 mm in 34 biopsies. In group B, the slice thickness was 4.8 mm in 82 biopsies and 2.4 

Discussion

Radiation exposure due to CT examinations has become a topic of increasing concern in the medical community and in the general population [9], [10]. Although there is an ongoing discussion on the extent of the risk associated with low-dose ionizing radiation, there is general agreement that the radiation dose in diagnostic procedures should be as low as reasonably achievable.

CT-guided interventions are reported to be associated with considerably high patient effective doses [7], [11]. This is

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