## 3 Results and Discussion
### Target Organs of MR Imaging  
This review analyzed the target organ of the MR imaging scan to which the NLM noise reduction algorithm was applied. The papers were classified into four types: brain, breast, cardiac, and \"other\". Figure 5 shows the overall publication numbers with respect to the target organ of the MR imaging scan, to which the NLM noise reduction algorithm was applied. Table 3 describes the characteristics for target organs of MR imaging, for the 25 included studies. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Study** & **Year** & **MR Imaging Technique** & **Used Specific Technique** \\ \hline [PERSON] et al. [39] & 2008 & General technique & T1, T2, PD \\ \hline [PERSON] et al. [40] & 2009 & Special technique & Parallel imaging \\ \hline [PERSON] et al. [41] & 2010 & Special technique & Dynamic contrast enhanced technique \\ \hline [PERSON] et al. [42] & 2010 & Special technique & Dynamic contrast enhanced technique \\ \hline [PERSON] et al. [43] & 2010 & General technique & T1, T2, PD \\ \hline [PERSON] et al. [44] & 2010 & Both & T1, T2, PD + GRAPPA, SENSE sequences \\ \hline [PERSON] et al. [45] & 2011 & General technique & T1, T2, PD \\ \hline [PERSON] et al. [46] & 2012 & General technique & T1, T2, PD \\ \hline [PERSON] et al. [47] & 2012 & Both & T1 + DWI, DTI \\ \hline [PERSON] et al. [48] & 2013 & General technique & T1, T2 \\ \hline [PERSON] et al. [49] & 2013 & Both & T1, T2, PD + DWI, DTI \\ \hline [PERSON] et al. [50] & 2014 & General technique & T1, T2 \\ \hline [PERSON] et al. [51] & 2014 & Both & T1, T2, PD + DWI \\ \hline [PERSON] et al. [52] & 2015 & Special technique & Susceptibility weighted imaging (SWI) \\ \hline [PERSON] et al. [53] & 2015 & General technique & T1 \\ \hline [PERSON] et al. [54] & 2015 & General technique & T1 \\ \hline [PERSON] et al. [55] & 2015 & General technique & T1, T2, PD \\ \hline [PERSON] et al. [56] & 2016 & General technique & T1 \\ \hline [PERSON] et al. [57] & 2016 & Both & T1, T2, PD + Internet brain segmentation \\ \hline [PERSON] et al. [58] & 2016 & General technique & T1, T2, PD \\ \hline [PERSON] et al. [59] & 2017 & Special technique & FLASH sequence \\ \hline [PERSON] et al. [60] & 2019 & Special technique & DWI \\ \hline [PERSON] et al. [61] & 2019 & Special technique & DWI \\ \hline [PERSON] et al. [62] & 2019 & General technique & T1, T2, PD \\ \hline [PERSON] et al. [63] & 2020 & General technique & T1 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Characteristics for MR imaging techniques from studies retrieved for systematic review. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Study** & **Year** & **Target Organ** \\ \hline [PERSON] et al. [39] & 2008 & Other (Brain + Abdomen) \\ [PERSON] et al. [40] & 2009 & Cardiac \\ [PERSON] et al. [41] & 2010 & Other (Brain + Breast) \\ [PERSON] et al. [42] & 2010 & Breast \\ [PERSON] et al. [43] & 2010 & Brain \\ [PERSON] et al. [44] & 2010 & Brain \\ [PERSON] et al. [45] & 2011 & Brain \\ [PERSON] et al. [46] & 2012 & Brain \\ [PERSON] et al. [47] & 2012 & Brain \\ [PERSON] et al. [48] & 2013 & Other (Brain + Knee) \\ [PERSON] et al. [49] & 2013 & Brain \\ [PERSON] et al. [50] & 2014 & Brain \\ [PERSON] et al. [51] & 2014 & Brain \\ [PERSON] et al. [52] & 2015 & Brain \\ [PERSON] et al. [53] & 2015 & Brain \\ [PERSON] et al. [54] & 2015 & Brain \\ [PERSON] et al. [55] & 2015 & Brain \\ [PERSON] et al. [56] & 2016 & Brain \\ [PERSON] et al. [57] & 2016 & Brain \\ [PERSON] et al. [58] & 2016 & Brain \\ [PERSON] et al. [59] & 2017 & Cardiac \\ [PERSON] et al. [60] & 2019 & Brain \\ [PERSON] et al. [61] & 2019 & Brain \\ [PERSON] et al. [62] & 2019 & Brain \\ [PERSON] et al. [63] & 2020 & Brain \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Characteristics for target organs of MR imaging from studies retrieved for systematic review. Figure 5: (a) Graph of the number of publications for various target organs of MR imaging scans using the NLM noise reduction algorithm.