Three-dimensional computer reconstruction of prostate cancer from radical prostatectomy specimens: evaluation of the model by core biopsy simulation

Can transrectal needle biopsy be optimised to detect nearly all prostate cancer with a volume of ≥0.5 mL? A three-dimensional analysis

OBJECTIVE

To investigate whether transrectal needle biopsy can be optimised to detect nearly all prostate cancer with a tumour volume (TV) of ≥0.5 mL.

MATERIALS AND METHODS

Retrospectively analysed 109 whole-mounted and entirely submitted radical prostatectomy specimens with prostate cancer. All tumours in each prostate were outlined on whole-mount slides and digitally scanned to produce tumour maps. Tumour map images were exported to three-dimensional (3D) slicer software (http://www.slicer.org) to develop a 3D-prostate cancer model. In all, 20 transrectal biopsy schemes involving two to 40 cores and two to six anteriorly directed biopsy (ADBx) cores (including transition zone, TZ) were simulated, as well as models with various biopsy cutting lengths. Detection rates for tumours of different volumes were determined for the various biopsy simulation schemes.

RESULTS

In 109 prostates, 800 tumours were detected, 90 with a TV of ≥0.5 mL (mean TV 0.24 mL). Detection rate for tumours with a TV of ≥0.5 mL plateaued at 77% (69/90) using a 12-core (3 × 4) scheme, standard 17-mm biopsy cutting length without ADBx cores. In all, 20 of 21 (95%) tumours with a TV of ≥0.5 mL not detected by this scheme originated in the anterior peripheral zone or TZ. Increasing the biopsy cutting length and depth/number of ADBx cores improved the detection rate for tumours with a TVof ≥0.5 mL in the 12-core scheme. Using a 22-mm cutting length and a 12-core scheme with additional volume-adjusted ADBx cores, 100% of ≥0.5 mL tumours in prostates ≤ 50 mL in volume and 94.7% of ≥0.5 mL tumours in prostates > 50 mL in volume were detected.

CONCLUSIONS

Our 3D-prostate cancer model analysis suggests that nearly all prostate cancers with a TV of ≥0.5 mL can be detected by 14-18 transrectal needle-biopsy cores. Using longer biopsy cutting lengths and increasing the depth and number of ADBx cores (including TZ) according to prostate volume are necessary as well.

Statistical 3D Distribution Analysis of Prostate Cancers in Korean Using Digital Processing Techniques

Objectives

Several researchers have shown that three dimensional (3D) distribution analysis of prostate cancer is helpful when initiating needle biopsy procedures. Knowledge regarding the distribution of prostate cancer could enhance understanding of the pathophysiology involved and improve detection of these malignancies. We propose utilizing digital processing techniques to analyze prostate cancer distribution in a 3D setting.

Methods

Pre-made radical prostatectomy sample slices were digitized with a resolution of 76 dpi. Slices of each sample were aligned and registered by deformation algorithm and interpolated for analysis of relative distribution statistics. We analyzed 80 samples saved in electronic medical record and compared the detection rate of preoperative needle biopsies and radical prostatectomies using our 3D analysis technique.

Results

The statistical 3D distribution of prostate cancer was evaluated using a 36-sector process. Results were represented in the following two ways: distribution of a single patient, and statistical distribution of prostate cancers of multiple patients. The overall concordance rate was 62.7% between the two methods; therefore a technique is needed which can raise this percentage.

Conclusions

We suggest using the normalization method to develop a software tool which permits reconstruction of the 3D distribution of prostate cancer from 2D legacy images and reduces the loss of image quality as well. This application will facilitate detection of prostate cancer by aiding in the determination of the most effective clinical position via partial sampling with decreased patient inconvenience.

[Prostate carcinoma]

Prostate cancer is the most common malignancy in men in Europe, North America, and in some African states. Early diagnosis in an asymptomatic stage is possible through the combination of digitorectal examination, PSA serum testing, and systematic biopsy. However, general screening is so far not recommended by the Urologic Societies, because the efficiency is not yet proved. Imaging is also not recommended for first-line screening. Novel functional methods of transrectal ultrasound (TRUS) and endorectal MRI can improve accuracy of tumor detection to more than 90% and can be used for TRUS- and now also MRI-guided biopsy leading to two- to threefold higher tumor detection rates. There is general agreement that all men over 50 years of age should be informed about the possibilities, benefits, and risks of the available methods for early tumor detection.

Computer technology in detection and staging of prostate carcinoma: A review

After two decades of increasing interest and research activity, computer-assisted diagnostic approaches are reaching the stage where more routine deployment in clinical practice is becoming a possibility [Kruppinski, E.A., 2004. Computer-aided detection in clinical environment: Benefits and challenges for radiologists. Radiology 231, 7-9]. This is particularly the case in the analysis of mammographic images [Helvie, M.A., Hadjiiski, L., Makariou, E., Chan, H.P., Petrick, N., Sahiner, B., Lo, S.C., Freedman, M., Adler, D., Bailey, J., Blane, C., Hoff, D., Hunt, K., Joynt, L., Klein, K., Paramagul, C., Patterson, S.K., Roubidoux, M.A., 2004. Sensitivity of noncommercial computer-aided detection system for mammographic breast cancer detection: pilot clinical trial. Radiology 231, 208-214] and in the detection of pulmonary nodules [Reeves, A.P., Kostis, W.J., 2000. Computer-aided diagnosis for lung cancer. Radiol. Clin. North Am. 38, 497-509]. However, similar approaches can be applied more widely with the promise of increasing clinical utility in other areas. We review how computer-aided approaches may be applied in the diagnosis and staging of prostatic cancer. The current status of computer technology is reviewed, covering artificial neural networks for detection and staging, computerised biopsy simulation and computer-assisted analysis of ultrasound and magnetic resonance images.

A comparison of the diagnostic performance of systematic versus ultrasound-guided biopsies of prostate cancer

Transrectal ultrasound (TRUS) is an important tool for urologists and radiologists in the detection of prostate cancer. Various TRUS-guided biopsy techniques are applied in clinical practice. Frequently, only the detection rates achieved with these methods are compared. Other diagnostic performance parameters, particularly the specificity and negative predictive value, are seldom compared. After extensive assessment of the available literature, this review describes the methods of TRUS-guided biopsy for prostate cancer detection. A distinction was made between systematic biopsies and biopsies that target a perceived (hypoechoic or Doppler-enhancing) lesion on imaging. Subsequently, the diagnostic performance (sensitivity, specificity, positive and negative predictive values, accuracies) was compared between these techniques. Imaging-guided biopsy showed better diagnostic performance than systematic biopsy with higher sensitivity. The combinations of sensitivity and specificity were highest for colour Doppler and contrast-enhanced targeted biopsy. Studies targeting hypoechoic lesions had relatively high sensitivity, but specificity was low. Presently however, with widespread prostate-specific antigen screening, fewer prostate cancers are hypoechoic, and the value of targeting hypoechoic lesions has diminished. Performing colour or contrast-enhanced Doppler biopsy or adding these techniques to systematic biopsies improves diagnostic performance, particularly by increasing sensitivity.

Three-dimensional reconstruction of basal cell carcinomas

BACKGROUND

Basal cell carcinoma (BCC) is the most common type of skin cancer. One of the main problems with BCC is the risk of local recurrence of the tumor after treatment. This is mainly due to its irregular outgrowths, which cannot be detected clinically.

OBJECTIVE

To better understand the tumor morphology and growth pattern of BCC, we tried to develop a method that provides a precise three-dimensional model of the tumor.

METHODS

Because Mohs surgery provides the best overview of the tumor and the tumor margins (both lateral and in depth), the reconstruction was based on slides from Mohs surgery. After digitization and processing of the slides, the tumor was then surrounded by a Mohs surgeon on a computer screen. These selections (lines) were used for a three-dimensional reconstruction of the tumor using MedSurf3D software.

RESULTS

This method allows three-dimensional reconstruction of any given BCC. The MedSurf3D software enables visualization of a three-dimensional model of the tissue, which is removed during the surgical procedure.

CONCLUSIONS

Three-dimensional reconstruction is a fascinating tool that might improve our understanding of the behavior, growth pattern, and tumor morphology of BCCs. This technique might also be useful in other fields of cutaneous oncology, such as the calculation of the tumor volume of melanomas.

Investigating the distribution of prostate cancer using three-dimensional computer simulation

The objective of this work was to investigate the distribution of prostate cancer using three-dimensional (3-D) computer simulation. Two hundred and eighty-one 3-D computer prostate models were constructed from radical prostatectomy specimens. An algorithm was developed which divided each model into 24 symmetrical regions, and it then detected the presence of tumor within an individual region. The distribution rate of prostate cancer was assessed within each region of all 281 prostate models, and the difference between the rates was statistically analyzed using Mantel-Haenszel methodology. There was a statistically significant higher distribution rate of cancer in the posterior half (57.2%) compared to the anterior half ( 40.5%; P=0.001). The base regions (36.8%) had a statistically significant lower distribution rate than either the mid regions (56.3%; P=0.001) or the apical regions (53.5%; P=0.001). The mid regions did have a statistically significant higher distribution rate compared to the apical regions (P=0.032). There was no statistically significant difference between the distribution rate on the left half (48.5%) compared to that on the right half (49.2%; P=0.494). The spatial distribution of prostate cancer can be analyzed using 3-D computer prostate models. The results illustrate that prostate cancer is least commonly located in the anterior half and base regions of the prostate. Through an analysis of the spatial distribution of prostate cancer, we believe that new optimal biopsy strategies and techniques can be developed.

Does site-specific labelling and individual processing of sextant biopsies improve the accuracy of prostate biopsy in predicting pathological stage in patients with T1c prostate cancer?

OBJECTIVE

To evaluate whether individual labelling and processing of the sextant of origin improves the accuracy of prostate biopsy in predicting the final pathological stage after radical prostatectomy in patients with T1c prostate cancer.

PATIENTS AND METHODS

The charts of 386 patients treated for prostate cancer by radical prostatectomy between January 1996 and June 1999 were reviewed. In all, 124 patients fulfilled the following inclusion criteria: no abnormality on digital rectal examination (DRE) or transrectal ultrasonography, a prostate specific antigen (PSA) level before biopsy of < or = 20 ng/mL, and prostate cancer diagnosed after one set of random sextant biopsies, with the cores being submitted in six separate containers individually labelled for the sextant of origin.

RESULTS

Within this series of patients with a low tumour burden, the preoperative PSA, biopsy Gleason score and unilateral vs bilateral involvement were not significant predictors of disease extension. The percentage of positive cores and the number and topography of positive sextants were both statistically significant predictors of organ-confined disease. Although these two variables appeared to be statistically equivalent on a first analysis in the overall series, a subgroup of patients was identified who benefited from the complete topographical information, i.e. those 52 (42%) patients with a Gleason score of < 7, 25-75% positive biopsies and < or =3 positive sextants.

CONCLUSION

These results support the individual labelling of biopsy cores in selected patients with a normal DRE and a moderately elevated PSA, as it helps to better predict the final pathological stage. This substantial benefit outweighs the additional effort by the pathologist.

Adenocarcinoma da próstata: a alteração hipoecogênica difusa da próstata é um achado ultra-sonográfico importante?

Avaliar se há associação entre a observação de alteração hipoecogênica difusa da próstata, com perda da demarcação entre a zona periférica e a glândula interna, e o diagnóstico de adenocarcinoma de próstata na biópsia prostática transretal. MATERIAIS E MÉTODOS: Avaliamos 143 homens com nível sérico de antígeno prostático específico maior do que 4 ng/ml. Todos os pacientes foram submetidos à ultra-sonografia endorretal e biópsia randomizada da próstata. RESULTADOS: Foi diagnosticado adenocarcinoma de próstata em 36,4% dos pacientes. A alteração hipoecogênica difusa da próstata, caracterizada por perda da demarcação entre a zona periférica e a glândula central, foi observada em 22 pacientes e correspondeu ao diagnóstico de adenocarcinoma de próstata em 21 deles (95,4%). CONCLUSÃO: A alteração hipoecogênica difusa da próstata constituiu um critério de suspeita ultra-sonográfica de adenocarcinoma de próstata altamente significativo, já que em 95,4% das próstatas que apresentavam essas características a biópsia foi positiva para adenocarcinoma de próstata

Analysis of three-dimensional ultrasound Doppler for the detection of prostate cancer

OBJECTIVES

To investigate the relative effectiveness of Doppler ultrasound quantitative measures in discriminating prostate cancer from normal prostate tissue. The true locations of prostate cancer within these prostates were determined by histologic examination after radical prostatectomy.

METHODS

Three-dimensional Doppler ultrasound data were acquired from 39 men before radical prostatectomy. The removed prostates were sectioned and all cancerous regions in each prostate were identified on whole-mount hematoxylin-eosin-stained slides. The ultrasound and histologic data were then spatially registered. Biopsy results were simulated on a grid of potential sites within each prostate. Along each simulated biopsy site, the amount of cancer was computed from the hematoxylin-eosin-identified cancerous regions and the peak speed-weighted pixel density (SWD) was compared.

RESULTS

By selecting the biopsy sites with higher associated SWDs within each sextant, the probability of having at least one positive biopsy within a prostate increased from 75% if the SWD was ignored to 85% if only the top 15% of potential biopsy sites in each sextant were selected. This trend was seen within each sextant individually as well.

CONCLUSIONS

Doppler ultrasound provides discriminatory information for prostate cancer using the SWD. Translating this into a practical strategy that might improve the yield of prostate biopsy remains under development. The results of our study indicate that biopsying regions of high Doppler color could potentially increase the cancer yield to a small degree and improve the accuracy of the biopsy results. These results also objectively verify previous visual studies suggesting a modest improvement with the use of color Doppler.

Importance of posterolateral needle biopsies in the detection of prostate cancer

OBJECTIVES

To determine whether needle biopsy of the posterolateral aspects of the prostate aids in prostate cancer detection. In the routine sextant biopsy strategy, the posterolateral aspects of the prostate are not sampled.

METHODS

Using an 18-gauge biopsy gun, we performed sextant biopsies and an additional nine needle biopsies in the pathology laboratory on 150 radical prostatectomy specimens performed for Stage T1c prostate cancer. The additional nine biopsies consisted of three midline biopsies and six (three each from the left and right) posterolaterally aimed biopsies from the apex, mid, and base regions of the gland. Significant tumors were defined as those greater than 0.5 cm3, or with a Gleason score of 7 or greater, or non-organ confined.

RESULTS

Of the 123 cases with cancer on repeated biopsy, in only 3 (2.4%) was the only cancer found in the midline biopsies. For the following analysis, we analyzed the data as if we had not done the midline biopsies. If one had performed only the routine sextant needle biopsies, in 31 (25.2%) of the 123 cases, tumor would have been missed; 20 of these tumors were significant, including 5 with extraprostatic extension. If one had performed only the more posterolateral six biopsies, in 15 cases (12.2%), tumor would have been missed; 5 of these tumors were significant, all of which were organ confined.

CONCLUSIONS

Adding routine midline biopsies does not appreciably increase the detection of cancer. If one were to only perform six needle biopsies of the prostate, these biopsies should be aimed more toward the posterolateral aspect of the gland. Maximum cancer detection results from combining both routine sextant and posterolateral needle biopsies.

Correlations among prostatic biopsy results, transrectal ultrasound findings and PSA levels in diagnosing prostate adenocarcinoma

OBJECTIVE

The objective of this study was to evaluate transrectal ultrasound (TRUS) findings and prostate-specific antigen (PSA) levels in relation to prostatic biopsy results and to analyze their individual and combined performances in diagnosing prostate adenocarcinoma (PAC).

METHODS

Men (n=143) with PSA levels above 4 ng/ml underwent TRUS and randomized ultrasound-guided prostatic biopsy through the peripheral zone, including additional hypoechoic nodules biopsies, if they were noted on TRUS. Data related to TRUS, biopsy, and PSA level results were then correlated.

RESULTS

A significant correlation between TRUS images suspicious for PAC and a biopsy-confirmed diagnosis of PAC, or between the lack of such images and a negative biopsy result, was not found. However, a significant correlation was found between positive biopsy results and PSA levels greater or equal to 10 ng/ml. The sensitivity of transrectal ultrasound in making a diagnosis of PAC was 63%, whereas its specificity was 73%.

CONCLUSION

We conclude that while the separate performances of these examinations were not effective in diagnosing PAC, the integrated use of these methods was more adequate for making the diagnosis.

Biopsy protocol stability in a three-dimensional model of prostate cancer: changes in cancer yield after adjustment of biopsy positions

OBJECTIVES

Transrectal ultrasound-guided prostate biopsies are often taken according to a systematic, standardized schedule. The diagnostic stability of this system was evaluated by moving the biopsies in a three-dimensional (3D) model.

METHODS

A computerized 3D reconstruction was made from each of 75 radical prostatectomy specimens. Simulated core biopsies imitated a standardized 10-biopsy protocol, including sextant biopsies. In total, 30,000 biopsies were generated by moving the standardized biopsies 1, 2, 3, and 4 mm (parallel needle shifts) or 5 degrees, 10 degrees, 15 degrees, and 20 degrees(rotation of the needle tip) in a random direction.

RESULTS

The diagnosis of the individual biopsy changed from cancer to benign or vice versa in 4.9% to 1 5.7% after 1 to 4-mm parallel needle shifts and 2.0% to 7.5% after 5 degrees to 20 degrees rotations. The corresponding figures for the final diagnosis of the 10-biopsy set were 0.8% to 9.6% and 0.5% to 3.2%. Transition zone biopsies containing cancer changed to benign more often than the other biopsies (P <0.001). Parallel needle shifts of 2 mm changed the diagnosis more often than the 15 degrees rotation (9.4% and 5.9%, respectively, P <0.001), although conveying the same overall needle shift.

CONCLUSIONS

The cancer yield of prostate biopsies is influenced even by small changes in needle positions. The transition zone biopsies are most likely to change from cancer to benign when moved. Changing the insertion point of the needle has a higher impact on cancer yield than rotating the tip.